Patent Publication Number: US-4322814-A

Title: Error detection for use in editing apparatus

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to editing apparatus and, more particularly, to an error detection arrangement for use in such editing apparatus. 
     In the field of signal recording, it often is desirable to modify or edit a recording by selectively inserting thereinto various bits and pieces which are derived from other recordings or signal sources. Video editing has become a highly specialized and advantageous art, whereby video signals which are recorded on a particular record medium, such as a magnetic tape, a magnetic disk, or the like, are edited by selectively assembling or inserting other video signals onto that record medium. For the purpose of the present discussion, the record medium on which the video signals are recorded is described as magentic tape which, presently, is the most common form of record medium that now is used for recording video programs. Typically, in the field of broadcast and commercial video tape recording, video signals which are recorded on one tape are reproduced by a video tape recorder (VTR) for an &#34;insert&#34; or &#34;assemble&#34; recording on another tape by another VTR. As is known to those of ordinary skill in the art of video editing, an &#34;insert&#34; edit operation describes the insertion of video signals into a predetermined location on a video tape, the &#34; inserted&#34; signals being preceded and followed by pre-existing video signals. In an &#34;assemble&#34; mode of operation, video signals are recorded in following relation (i.e. assembled) to pre-existing information. 
     As is recognized, to carry out the insert and assemble edit modes of operation, it is necessary for an operator to select appropriate portions, or blocks, of video signals which are to be reproduced from one tape (referred to generally as the source or playback tape) and which are to be recorded at other locations on the recording (or destination) tape. That is, the operator must be aware of the particular addresses on the source tape at which desired video signals are recorded as well as addresses on the destination tape at which new video signals are to be placed. These &#34;addresses&#34; on the respective video tapes generally are recorded as time code addresses, each of which separately identifies a respective frame of the recorded video signal. An example of one type of time code address which is used with, for example, the recording of NTSC signals is the so-called SMPTE (Society of Motion Picture and Television Engineers) time code which represents frame addresses in terms of hours, minutes, seconds and frames, up to a maximum value of 23 hours, 59 minutes, 59 seconds and 29  frames. Although other acceptable time code addresses are known, for convenience, and in the interest of simplification, the present discussion refers only to this SMPTE time code. 
     It is conventional to record the time code longitudinally, that is, in serial tracks along a length of the video tape. Time code generators and readers are known for the recording and reading of such time codes as the video tape is transported. These time codes, as read from the video tape, are used to designated so-called &#34;edit-in&#34; and &#34;edit-out&#34; locations of the respective playback and recording tapes. 
     To carry out an edit operation, the time code addresses which identify the particular frames on the playback tape which define the video information that is to be re-recorded on the recording tape are marked, or stored, as the edit-in and edit-out points. For an insert edit mode, the desired edit-in and edit-out points on the recording tape likewise are marked, or stored. Once an operator confirms that the material, or video signals, lying between the edit-in and edit-out points on the playback tape is correct and should be re-recorded, or transferred, between the edit-in and edit-out points on the recording tape, the actual transfer of video signals may occur. Such confirmation of this edit operation is known as a &#34;preview&#34;, and the previewed operation may be monitored on a suitable video display monitor device. If changes are to be effected to the respective edit-in and edit-out points, for example, if the operator finds other material which he wishes to transfer from the playback tape to the recording tape, or material which should be deleted from the recording tape, the time code addresses which define the respective edit points may be suitably changed. 
     In some types of edit operations, it is desirable to transfer some or all of a video scene but not its accompanying audio portion. Similarly, it may be desirable to transfer only the audio portion of a recording. The result of this so-called &#34;split&#34; edit operation is a video recording accompanied by audio information that has been separately prepared. As an example of this, in preparing a segment for a television news broadcast, a particular newsworthy video scene may be recorded on one tape with whatever audio information accompanied that scene; and another video scene, such as that of the news commentator, may be recorded on another tape with its accompanying audio commentary. When a split-edit operation is carried out, the resultant recording may consist of the particular newsworthy video scene accompanied by the audio commentary. This split-edit procedure may be carried out by, for example, transferring the newsworthy scene to the tape on which the audio commentary is recorded or, conversely, by transferring the audio commentary to the tape on which the newsworthy scene is recorded. 
     As may be appreciated, it is advantageous to provide video editing apparatus with a split-edit capability such that, broadly, video signals at one location of, for example, the playback tape and audio signals at another location may be transferred to the recording tape. That is, as the playback and recording tapes are transported, the video signals commencing at point A on the playback tape, and then the audio signals commencing at point B are transferred, until point C is reached, whereat the edit operation terminates. This is referred to as a &#34;split-in&#34; edit operation wherein the &#34;edit-in&#34; locations are split between the video and audio signals. In a &#34;split-out&#34; operation, the points at which recording terminates are split: for example, the recording of the video signals terminates at point D and the recording of the audio signals terminates at point F. Video editing apparatus that can carry out a combined split-in and split-out operation easily, and under the control of an operator who is not necessarily highly skilled, is desirable. 
     In a typical video tape recording format, two audio tracks are provided upon which different audio signals may be recorded. Use of such separate aduio tracks can be turned to account in a split-edit operation by &#34;splitting&#34; the recording of the audio signals in these tracks. Thus, for example, in a split-in operation, recording of the video signals may commence when the playback (or recording) tape reaches point A, recording of the aduio signals in one track may commence when the tape reaches point B, and recording of the audio signals in the other track may commence when the tape reaches point C. An analogous edit-out operation likewise may be carried out. It is recognized that this offers advantageous flexibility and enhances the quality of video editing. 
     Many video editing devices known heretofore, if capable of performing split-edit operations, generally cannot carry out a split-out operation. Also, although separate audio tracks are provided in the typical video tape recording format, such devices do not function to &#34;split&#34; the recording of these audio signals. That is, the transfer, or edit, of the audio signals is accomplished simultaneously--separate edit-in or edit-out locations for such audio signals are not obtainable. A further disadvantage attending these video editing devices is a limitation on the split-in edit locations. Generally, a split-in location for the audio signals is constrained within a limited range following the video split-in location. Consequently, audio signals may not be transferrable before the video signals. Also, it may not be possible to select an audio edit-in point (such as the aforementioned point B) that is satisfactorily removed from the video edit-in point (the aforementioned point A). This may inhibit the overall capabilities and artistic results of the edit operation. 
     Such disadvantages are overcome by the novel editing apparatus described in copending applications Ser. No. 139,444 and Ser. No. 139,448, each filed Apr. 11, 1980. In that editing apparatus, video and audio edit-in as well as edit-out points may be selected by simple push-button operation. Common edit-in and edit-out points may be selected, respectively, for the video and audio signals or, if the operator desires, individual edit-in and edit-out points may be assigned. To assist the operator in setting up and carrying out edit operations, the editing apparatus advantageously is provided with display registers for displaying position data representing the various edit points, and with selector switches for assigning the displayed position data to those video and audio signals whose transfer is desired. 
     The aforedescribed editing apparatus can be operated by one who need not be a highly skilled technician. Therefore, it is desirable to provide automatic error detection to sense that the particular parameters which have been selected for the edit operation are enabling. That is, the individual edit-in and edit-out points should be checked to make sure that the edit operation can proceed as desired. For example, edit-out points should follow edit-in points, split-in and split-out points should be selected to be intermediate the start and end locations for the edit, the individual video and audio signals that are selected to be &#34;split in&#34; also should be &#34;split-out&#34;, and the like. Furthermore, if an error condition is detected, appropriate indications should be produced which apprise the operator of the existence of the detected error condition, its probable location, and its probable cause. Moreover, the actual implementation of the edit operation should be inhibited in the presence of an error condition. 
     So far as is known, video editing apparatus having a satisfactory automatic error detection feature of the type described above is not readily available. 
     OBJECTS OF THE INVENTION 
     Therefore, it is an object of the present invention to provide improved video edit apparatus. 
     Another object of this invention is to provide such edit apparatus which avoids the disadvantages and defects attending prior art edit apparatus and which includes an automatic error detection arrangement. 
     A still further object of this invention is to provide video editing apparatus which is particularly adapted to perform split-edit operations and which is adapted to sense erroneous parameters which may have been selected for such operations. 
     An additional object of this invention is to provide video edit apparatus in which respective edit-in and/or edit-out points for both a source, or playback, medium and a destination, or record, medium are selected for the video and audio signals, which points are checked to determine if they are enabling for completing an edit operation. 
     Yet another object of this invention is to provide video edit apparatus wherein the time code addresses for different edit points for video and audio signals are used in carrying out a split-in or a split-out operation, which time code addresses are checked for the purpose of detecting an error condition. 
     A still further object of this invention is to provide video edit apparatus which enables an operator to select desired split-edit points by simple push-button operation, and which detects erroneous parameters that may have been selected. 
     Yet another object of this invention is to provide video edit apparatus for use with, for example, video tape having two audio tracks, in which separate edit points may be selected for the video signals and for the audio signals in the respective tracks, as desired, by relatively simple operation. 
     Various other objects, advantages and features of the present invention will become readily apparent from the ensuing detailed description, and the novel features will be particularly pointed out in the appended claims. 
     SUMMARY OF THE INVENTION 
     In accordance with this invention, editing apparatus is provided for use with playback and recording devices such as VTR&#39;s, wherein different signals (e.g. video and audio signals) on a first record medium, such as video tape, are transferred to a second record medium, the relative positions of the media being represented by position data. The editing apparatus comprises a console having a plurality of display registers for displaying position data, a plurality of register selector switches associated with corresponding ones of the display registers, each register selector switch being operable to select its associated display register, a plurality of register indicators associated with respective ones of the display registers, a plurality of signal selector switches, each signal selector switch being operable to select particular ones of the signals reproduced from the first medium to be recorded on the second medium when one of the media reaches a position represented by the position data displayed in a selected display register, a plurality of signal select indicators associated with respective ones of the signal selector switches, and control switches operable to initiate edit operations. A central processing unit responds to the selected operation of the signal selector switches and the register selector switches for assigning at least one of the different signals (i.e. one of the video or audio signals) for transfer to the second medium when that medium reaches a relative position represented by the position data displayed in a selected display register. The central processing unit includes an error detecting arrangement that is responsive to the operation of a control switch to detect if the data displayed in the selected display register is enabling for carrying out the edit operation and, if not, to inhibit the edit operation from being carried out and to actuate selected ones of the indicators to apprise an operator of an error condition. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The following detailed description, given by way of example, will best be understood in conjunction with the accompanying drawings in which: 
     FIG. 1 is a front view of a console which is used with the present invention; 
     FIG. 2 is a block diagram of video editing apparatus with which the present invention is incorporated; 
     FIG. 3 is a block diagram representing a portion of the apparatus of FIG. 2 by which data from the console is communicated to the central processing unit; 
     FIGS. 4A and 4B are partial block, partial logic diagrams representing a portion of the apparatus of FIG. 2 in which data is communicated from the central processing unit to the console; 
     FIG. 5 is a partial block, partial logic diagram representing that portion of the apparatus of FIG. 2 by which the displays on the console are energized; 
     FIGS. 6A-6E are timing diagrams which are useful in understanding a portion of the circuitry shown in FIG. 4B; 
     FIG. 7 is a logic diagram showing in greater detail, a portion of the circuitry shown in FIG. 4B; 
     FIGS. 8A-8F and 9A-9K are timing diagrams which are useful in understanding the operation of the circuits shown in FIG. 7; 
     FIG. 10 is a logic diagram of a control circuit which is used to control a portion of the circuitry illustrated in FIG. 4A; 
     FIGS. 11A-11L are timing diagrams which are useful in understanding the operation of the logic circuits shown in FIG. 10; 
     FIGS. 12A-12C are flow charts which are useful in understanding the operation of the central processing unit in accordance with the present invention; 
     FIG. 13 is a functional block diagram which is useful in understanding the flow charts of FIGS. 12A-12C; and 
     FIGS. 14A-14D are flow charts which explain the operation of the central processing unit in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION OF A CERTAIN PREFERRED EMBODIMENT 
     In video editing apparatus, video signals that are recorded on one medium, or that are derived from some other source, are transferred, or re-recorded, onto another medium. Although such record media may comprise magnetic tape, magnetic disks, and other conventional recording media, it will be assumed, for the purpose of the present discussion, that magnetic tape is used. Thus, the video editing apparatus will be described in conjunction with video tape recording (VTR) devices, including a source VTR operable with a playback tape from which pre-recorded video signals are reproduced, and a destination VTR operable with a recording tape onto which the reproduced video signals are recorded. 
     As is known to those of ordinary skill in the art, when video signals are recorded on magnetic tape, time code addresses also are recorded in a longitudinal track. Such time code addresses serve to identify the respective frames of video signals such that, during an edit operation, any desired frame can be addressed such that the addressed frame may be reproduced from the source tape, or the addressed frame may be erased, such as by &#34;over-recording&#34; on the destination tape. As mentioned above, one type of time code address which is used is the SMPTE code. In addition to recording a time code address, control pulses, known as control track signals, also are recorded in predetermined relation with the commencement of a field or frame of video signals. Such control track signals may be counted and used as frame addresses; although it is much preferred to utilize the specific time code addresses for this purpose. Nevertheless, for the purpose of the present discussion, since both time code addresses and control track signals may be used to represent the relative position of the video tape upon which such signals are recorded, the expression &#34;position data&#34;  or &#34;position data signals&#34; will be used to refer to such address signals and control track signals. 
     Turning now to FIG. 1, there is illustrated a front view of a console 10 which is used with video editing apparatus in which the present invention is incorporated. Console 10 conveniently is divided into a plurality of sections, including a playback section, a recording section, a data-handling section, and a control section. Also included on console 10 is a power on/off switch 12 to supply electrical power to the illustrated console. A SYNCHRONIZE lamp 14 is provided adjacent power on/off switch 12. The purpose of this SYNCHRONIZE lamp is to indicate when the playback and recording tapes are transported in synchronism. It may be appreciated that, in order to carry out an edit operation, a particular edit-in point should be selected for each of the playback and recording tapes. Typically, once these appropriate edit-in points have been selected, both the playback and recording tapes are rewound, or &#34;pre-rolled&#34; a particular distance. Then, the playback and recording tapes are advanced toward the selected edit-in points. For a proper edit operation, that is, to provide proper transfer of the video signals from the playback tape to the recording tape, it is necessary that the playback and recording heads rotate in synchronism with each other, that the playback and recording tapes advance in synchronism with each other, and that the edit-in points on both tapes arrive at their respective heads simultaneously. Conventional servo apparatus is provided to insure that, during the forward movement of the playback and recording tapes from their respective pre-rolled positions, this synchronism occurs. SYNCHRONIZE lamp 14 provides an indication that this synchronous &#34;lock-up&#34; condition has been attained. For example, SYNCHRONIZE lamp 14 may flash while the servo apparatus attempts synchronous operation, and then this lamp may be energized continuously once the lock-up condition has been attained. 
     A MANUAL EDIT lamp 16 is provided adjacent SYNCHRONIZE lamp 14 and is adapted to indicate when a manual edit operation is to be carried out. During normal automatic editing, this MANUAL EDIT lamp is extinguished. However, for those instances where an operator prefers to carry out a manual edit operation, this MANUAL EDIT lamp will be energized. 
     A color frame synchronizing section is adjacent MANUAL EDIT lamp 16. This color frame synchronizing section includes an ON/OFF switch 20 and associated indicator lamp 21, a SET switch 18 and associated indicator lamp 19 and a PAL 4/8  switch 22. It is appreciated that, in conventional color television signals, the phase of the chrominance subcarrier in one particular line in one frame differs from the phase of that subcarrier in the same line in the next frame. For example, in the NTSC system, the phases of the chrominance subcarrier in the same line in adjacent frames differ from each other by 180°. During an edit operation, the first frame of video signals reproduced from the playback tape may exhibit an out-of-phase relationship with the last frame of the video signals on the recording tape. To provide color frame synchronization, it may be necessary to select either the preceding or next-following frame from the playback tape by providing a correction offset to the position data (e.g. the time code address) associated with the playback tape. Such correction offset is carried out by turning ON/OFF switch 20 on, effecting a frame adjustment (described generally below) and operating SET switch 18. An indication of improper color frame synchronization is provided by the blinking, or flashing, of color frame SET lamp 19. This, of course, would mean that an additional address offset is needed. Alternatively, if ON/OFF switch 20 is operated to its off condition, color frame synchronization is dispensed with, and the edit operation is carried out without such color frame synchronization. It may be appreciated that, if color frame synchronization is desired, edit previews (to be described) should be performed in order to determine if color frame synchronization has been achieved successfully, prior to the carrying out of an actual edit operation. 
     PAL 4/8 switch 22 is operable to select between four-field or eight-field synchronization when the video signals are PAL color television signals. As is known, the phase of the chrominance subcarrier of a particular line in one frame of a PAL video signal is out-of-phase by 90° with the chrominance subcarrier in that same line in the next-following frame, whereby the chrominance subcarrier varies in phase in a so-called four-frame (or eight-field) sequence. The V component of the chrominance signal is reversed at every second line, thus resulting in the so-called four-field sequence. The PAL 4/8 switch enables the operator to select between these sequences. 
     Adjacent the color frame synchronizing section are CTL/TIME selection switches 24 and 28. Switch 24 is associated with the playback tape of the source VTR and switch 28 is associated with the recording tape of the destination VTR. These switches are adapted to select either the control track signals or the time code addresses as the position data to be used in the edit operation. Specifically, if switches 24 and 28 are operated in the CTL position, then the control track signals read from the playback and recording tapes are used as the position data signals, and indicator lamps 25 and 29, respectively, are energized. Alternatively, if switches 24 and 28 are operated to their respective TIME positions, then the time code addresses read from the playback and recording tapes are used as the position data signals, and lamps 26 and 30, respectively, are energized. 
     Adjacent the CTL/TIME selector switches are the MANUAL EDIT switch 32, SEND STATUS switch 34, REACTION TRIM control 36, PREROLL time switch 38 and BLANKING switch 40. MANUAL EDIT switch 32 is adapted to select either an automatic editing operation or, when operated to its ON condition, to select a manual edit mode of operation. In the manual edit mode, MANUAL EDIT lamp 16 is energized and the edit operation is carried out in response to the manual operation of the operator. That is, when the playback and recording tapes reach their desired locations, the operator merely operates a RECORD switch 170 (disposed in the control section of the illustrated console) to effect a recording of the video signals then reproduced from the playback tape. 
     SEND STATUS switch 34 is adapted to supply the central processing unit that is used with console 10 with the particular control parameters which are selected by operation of the color frame synchronizing controls, the CTL/TIME switches, the MANUAL EDIT switch, the REACTION TRIM switch and the PREROLL time switch. Adjustments of these respective controls do not effect a corresponding change in the parameters supplied to the central processing unit unless SEND STATUS switch 34 is operated. 
     REACTION TRIM switch 36 is adapted to correct, or compensate (i.e. &#34;trim&#34;) for a delayed reaction on the part of the operator. This compensation is selectable between 0 and 12 frames. For example, in setting up the respective edit-in and edit-out points for an edit operation, let it be assumed that, when the tape is advanced at its normal playback/record speed, the operator&#39;s reaction to setting the edit-in point is delayed. If this delay is, for example, equal to the amount of time that 6 frames have been transported, then, without any compensation, the actual edit-in point will be displaced from the edit-in point desired by the operator by 6 frames. However, by setting REACTION TRIM switch 36 to a &#34;trim&#34; of 6 frames, the operator&#39;s delayed reaction is compensated. That is, the actually selected edit-in point automatically will be reduced by 6 frames so as to be equal to the desired edit-in point. It should be recognized that, with this setting of REACTION TRIM switch 36, all edit-in and edit-out selections will be compensated by this amount. 
     PREROLL TIME switch 38 is selectable to establish a desired rewind time for the respective playback and recording tapes prior to their edit-in points. For example, depending upon the setting of this PREROLL TIME switch, the playback and recording tapes both will be rewound, or prerolled, by an amount represented by the setting of PREROLL TIME switch 38 when an edit operation is to be carried out or previewed. It is recalled that, as these tapes are advanced from their pre-rolled positions, SYNCHRONIZE lamp 14 will flash until the tapes are transported in synchronism, that is, until such tapes are &#34;locked-up&#34;, and then this lamp will be energized continuously. 
     BLANKING switch 40 is adapted, when operated, to &#34;blank&#34; all displays on console 10. This may be desired during, for example, a manual edit operation wherein these displays may distract the operator. Although the data which is displayed by such displays is blanked, such data nevertheless remains stored for subsequent use. 
     The playback and record sections of console 10 are of substantially similar construction. In the interest of brevity, only the playback section is described. It will, of course, be appreciated that the following description is equally applicable to the record section of the console. The playback section is provided with a plurality of display registers, referred to herein as an IN register 50, an OUT register 54 and a tape timer register 58. IN register 50 is adapted to display position data, and represents the edit-in point on the playback tape. Preferably, the position data displayed by IN register 50 is a time code address, such as the SMPTE time code address in terms of hours, minutes, seconds and frames, and may be derived either from time code data reproduced from the tape or from control track signals that are reproduced from the tape and counted. In an alternative embodiment, this position data is constituted by a frame count. IN register 50 sometimes may be referred to herein as the edit-in or play IN register. 
     OUT register 54 is adapted to display the position data representing the edit-out point of the playback tape. This position data preferably is in the form of a time code address. OUT register 54 sometimes may be referred to herein as the edit-out or play OUT register. 
     Tape timer register 58, which also may be referred to as the present position register, is adapted to display the position data representing the present position of the playback tape. As will be explained below, tape timer register 58 is updated continually as the playback tape is moved. If the playback tape is transported in the forward direction, the position data displayed by tape timer register 58 is incremented. Conversely, if the playback tape is rewound, the position data displayed in this tape timer register is decremented. 
     Register selector switches 52, 56 and 60 are associated with IN register 50, OUT register 54 and tape timer register 58, respectively. Selector switch 52 is referred to herein as the edit-in (or, play in) switch; selector switch 56 is referred to as the edit-out (or play out) switch and selector switch 60 is referred to as the mark enable switch. These switches are used to control the transfer of position data between the illustrated display registers and, depending upon the order in which such switches are operated, function as &#34;source&#34; and &#34;destination&#34; switches. More particularly, the first of switches 52, 56 and 60 which is operated serves to designate its associated display register as a &#34;source&#34; register, and this switch thus is considered to be a source switch. The operation of one of switches 52, 56 and 60 as a source switch thus determines the particular display register from which data is to be transferred. That is, the data is transferred from a source register to a destination register. After one of switches 52, 56 and 60 is operated, the second of these switches to be operated serves to designate its associated display register as a destination register and, consequently, this switch is considered to be a destination switch. Thus, and as an example, if mark enable switch 60 is operated as the source switch, the operation of either of edit-in switch 52 or edit-out switch 56 functions as a destination switch to designate IN register 50 or OUT register 54 as a destination register, whereby the position data in tape timer register 58 is transferred either to IN register 50 or to OUT register 54. It may be appreciated that this is a typical operation to establish the edit-in and edit-out points. 
     A respective indicator also is provided in association with each of edit-in switch 52, edit-out switch 56 and mark enable switch 60. These indicators preferably are indicator lamps and, if the selector switches are constructed as push-button switches, each such lamp may be provided in a common housing with its associated switch. Alternatively, these indicators may be other light sources, such as LED&#39;s, LCD&#39;s or the like. As will be explained in greater detail below, when a particular selector switch is operated as a source switch, its associated lamp provides a distinctive indication thereof, thus apprising the operator as to his selection of the source switch. In the embodiment described herein, the distinctive indication provided in response to the operation of edit-in and edit-out switches 52 and 56 is a flashing indication, and the indication provided in response to the operation of the mark enable switch is a steady-state energization. Thus, in the aforementioned example, if mark enable switch 60 is operated as the source switch, the indicator lamp associated therewith is continuously ON. If the edit-in or edit-out switch is operated, the respective lamp associated therewith flashes. Also, the indicator associated with edit-out switch 56 may be operated to provide an error indication. 
     As mentioned above, the record section of console 10 is substantially similar to the playback section, and IN register 80, OUT register 84 and tape timer register 88 correspond to aforedescribed registers 50, 54 and 58, respectively. Similarly, edit-in switch 82, edit-out switch 86 and mark enable switch 90 are similar to selector switches 52, 56 and 60, respectively. It will be clear, from the ensuing detailed discussion, that the selector switches in the playback section may be operated independently of the selector switches in the record section, and data may be transferred from one display register to another. 
     Both the playback and record sections of console 10 are provided with suitable tape-movement controls. These controls are substantially the same and, in the interest of brevity, only the controls provided in the playback section will be described. These controls include a PLAY switch 62, a STOP switch 64, a PREVIEW switch 66, a CUE switch 68, a JOG switch 70, a SHUTTLE switch 72 and a speed/direction control 74. PLAY switch 62, which may be a push-button switch associated with an indicator lamp provided in, for example, a common housing, is adapted, when operated, to initiate a playback operation such that video signals are reproduced from the playback tape. STOP switch 64, which also may be constructed as a push-button switch, is adapted, when operated, to halt tape motion of the playback tape. 
     Speed/direction control 74 is adapted to cooperate with JOG switch 70 and with SHUTTLE switch 72 to control the direction and speed at which the playback tape is moved. For example, if JOG switch 70 is operated, the amount of playback tape which is advanced is determined by the angular rotation of speed/direction control 74. Furthermore, the direction in which this tape is moved is a function of the clockwise or counterclockwise rotation of control 74. For example, if JOG switch 70 is operated and if speed/direction control 74 is rotated in the clockwise direction by a relatively small angular amount, then a correspondingly small length of playback tape is advanced in the forward direction. Successive rotary movements of control 74 result in incremental advances, or &#34;jogging&#34; of the playback tape. 
     When SHUTTLE switch 72 is operated, the playback tape is advanced at a speed and direction determined by the angular rotation of speed/direction control 74. For example, with the SHUTTLE switch operated, a relatively small angular displacement in the clockwise direction of control 74 results in advancing the playback tape at a correspondingly slow speed. If control 74 had been rotated in the counterclockwise direction, the playback tape would have been rewound at a speed determined by the angular rotation of this control. When control 74 is returned to its initial, or 0° position, the playback tape is stopped. 
     Thus, the use of JOG and SHUTTLE switches 70 and 72, in cooperation with speed/direction control 74, enables the operator to drive the playback tape at a controlled speed so as to search for, or approach, a desired tape position. It is appreciated that, as the playback tape is driven in this manner, the position displayed by tape timer register 58 correspondingly is changed. When a desired location of the tape is reached, the relative position thereof is displayed by the position data in tape timer register 58. 
     PREVIEW switch 66 is adapted, when operated, to enable a television monitor connected to the playback VTR to display the video and audio signals which will be reproduced from the playback tape if an actual edit operation is carried out. More particularly, the playback tape will rewind, or pre-roll, to a location upstream of the edit-in point displayed in the IN display register 50. It is appreciated that the length of this pre-roll is determined by the setting of PREROLL TIME switch 38. Then, after this initial preroll operation, the playback tape will be advanced. In order to provide the operator with only that video and audio information which will be transferred to the recording tape during the actual edit operation, the display monitor will be blank, or will display a &#34;black&#34; video picture, until the playback tape has reached the edit-in point. At that time, blanking of the display monitor will be terminated and the monitor will display the video picture corresponding to the video signals then reproduced from the playback tape. When the playback tape reaches its edit-out point, blanking of the display monitor will resume. Thus, when PREVIEW switch 66 is operated, the display monitor will exhibit a black-video-black picture corresponding to the pre-rolled video signals, the video signals which will be re-recorded on the recording tape, and then the succeeding video signals reproduced from the playback tape. The operator will perceive only that information which will actually be re-recorded during the edit operation. 
     CUE switch 68 is adapted, when operated, to actuate the playback VTR such that the playback tape is driven to a selected position. The position to which the playback tape is driven is dependent upon whether edit-in switch 52 or edit-out switch 56 has been actuated. For example, if the edit-in switch is operated and then the CUE switch is operated, the playback tape is driven to the position represented by the position data in IN display register 50. Alternatively, if edit-out switch 56 had been operated and then CUE switch 68 is operated, the playback tape is driven to the position represented by the position data in OUT display register 54. The playback tape also may be driven to other positions represented by position data in display registers 118, 126 or 142 of the data handling section of console 10, as will be described. Thus, an operator may drive the playback tape to a selected position merely by operating CUE switch 68. For a complete description of a cue operation, reference is made to copending application (attorney&#39;s Ser. No. 139,691), the disclosure of which is incorporated herein. 
     Switches 62, 64, 66, 68, 70 and 72 may be provided with associated indicators such that when a respective one of these switches is operated, a corresponding indication of the selected switch is provided. If these switches are push-button switches, the indicators associated therewith may comprise lamps which, preferably, are disposed in the same housing as such push-button switches. 
     PLAY switch 92, STOP switch 94, PREVIEW switch 96, CUE switch 98, JOG switch 100, SHUTTLE switch 102 and speed/direction control 104 included in the record section of console 10 are similar to the corresponding switches and control device described hereinabove in respect of the play section. It should be noted, however, that when PREVIEW switch 96 is operated, the display monitor connected to the recording VTR will display a video picture corresponding to the pre-rolled poriton of recording tape and then the video picture will be blanked while the recording tape advances from its edit-in point to its edit-out point (these points being represented by the position data in display registers 80 and 84, respectively), and once the recording tape reaches its edit-out point, the monitor no longer will be blanked but will display the video picture corresponding to the reproduced video signals from the recording tape. Thus, a &#34;preview&#34; operation for the recording tape is displayed as a video-blank-video picture. 
     Referring now to the data handling section of console 10, this section is comprised of upper and lower portions. The upper portion of the data handling section is comprised of an ASSEMBLE MODE switch 110, signal selector switches comprising a video (V) switch 112, an audio-1 (A-1) switch 114, and and audio-2 (A-2) switch 116, a display register 118, an associated register selector switch 120, referred to as the EVENT-1 switch, a display register 126 and an associated register selector switch 128, referred to as the EVENT-2 switch. Display registers 118 and 126 also are referred to as the EVENT-1 and EVENT-2 registers, respectively. The purpose of these signal and register selector switches and display registers is to carry out a so-called &#34;agenda edit&#34; mode of operation. ASSEMBLE MODE switch 110 is adapted, when operated, to condition the setting up of an assemble-edit operation. 
     It is appreciated that, in a typical format for recording video signals for broadcast purposes, two separate audio tracks are recorded longitudinally on the tape. In some edit operations, it is preferred to transfer the video signals from the playback tape to the recording tape at a time which differs from the transfer of the audio signals. Also, it may be desired to transfer the audio signals from one audio track on the playback tape at a time which differs from the transfer of the audio signals from the other audio track. The agenda-edit operation permits such &#34;split&#34; recording of video and audio signals. For example, the video signals from the playback tape may be re-recorded on the recording tape prior to the time that the audio signals are re-recorded. Alternatively, the audio signals from the playback tape may be re-recorded on the recording tape prior to the time that the video signals are re-recorded. In addition to staggering the time at which the video and audio signals are re-recorded on the recording tape, known as a &#34;split-in&#34; operation, an agenda-edit operation also may be carried out to stagger the times at which the re-recording of these signals terminates. This latter operation is known as a &#34;split-out&#34; mode. The operation of video (V) switch 112, audio-1 (A-1) switch 114 and audio-2 (A-2) switch 116 enable this split recording, or agenda-edit operation. Each of the V, A-1 and A-2 switches 112, 114 and 116, respectively, may be constructed as a push-button switch. Indicators, such as lamps, are provided with each of these switches and, preferably, such lamps are mounted in the same housing as the push-button switch. Moreover, each switch preferably is provided with two indicator lamps, viz. an indicator lamp associated with the upper half of the switch and an indicator lamp associated with the lower half thereof. The manner in which these switches and associated indicator lamps operate to establish an agenda-edit mode of operation will be described below. 
     EVENT-1 register 118 and EVENT-2 register 126 may be similar to aforedescribed IN and OUT registers 50 and 54. Each of these event registers is adapted to display position data. Furthermore, EVENT-1 and EVENT-2 switches 120 and 128 may be similar to aforedescribed edit-in switch 52 and edit-out switch 56 such that, when operated, the event register associated therewith is designated either as a source or destination register. An indicator, such as a lamp disposed in the same housing thereof, is associated with each of EVENT-1 and EVENT-2 switches 120 and 128 so as to provide a distinctive indication that its associated switch has been operated as a source switch. These indicators also operate to provide an error indication, as will be described. 
     Additional indicators 122 and 124 are associated with EVENT-1 register 118 and, similarly, additional indicators 130 and 132 are associated with EVENT-2 register 126. Indicator 122 may comprise, for example, a light emitting diode (LED), or other suitable light source, and is referred to as a record (R) indicator. This record (R) indicator 122 is adapted to be energized when position data in EVENT-1 register 118 is transferred thereto from any of the display registers provided in the record section of console 10. Indicator 124 is referred to as a playback (P) indicator and is adapted to be energized when the position data in EVENT-1 register 118 is transferred thereto from a display register provided in the playback section of the console. Similarly, record (R) indicator 130 and playback (P) indicator 112 are associated with EVENT-2 register 126, and these indicators are adapted to be energized to represent the source (record or playback section) of the position data in EVENT-2 register 126. These record and playback indicators also are referred to herein as &#34;direction&#34; indicators in that they represent the &#34;directional source&#34; (recording or playback tape) from which the position data is derived. These indicators also are operated to provide error indications. 
     The upper portion of the data handling section of console 10 also is provided with SPLIT OUT control switches consisting of a SPLIT OUT PREVIEW switch 134 and a SPLIT OUT selector switch 136. As mentioned above, an agenda-edit mode can be established as a split-in or a split-out operation, wherein the positions at which transfer of the video and audio signals commences and terminates are selected and displayed in respective registers, to be described. In the split-in operation, the edit-in points are &#34;split&#34; among the video and audio signals. In the split-out operation, the edit-out points are &#34;split&#34; among the video and audio signals. The SPLIT OUT control switches, and particularly SPLIT OUT switch 136, enable the respective edit-out points for the video and audio signals to be established. 
     It will be appreciated that a split-in or a split-out agenda-edit mode may be established for the playback tape and/or for the recording tape. If a split-out agenda-edit operation is selected, the operation of SPLIT-OUT PREVIEW switch 134 enables a display monitor connected to the record VTR to display a &#34;preview&#34; of the split-out agenda-edit operation. 
     As will be described below, during an agenda-edit operation, EVENT-1 register 118 and EVENT-2 register 126 will display either edit-in or edit-out points. For a split-in agenda-edit operation, these display registers will display position data which define the positions along either the playback tape, at which the respective video and audio signals are to be transferred to the recording tape or, if desired, the position data representing those positions along the recording tape at which incoming video and audio signals are to be recorded. If this position data represents the edit-in points selected for the playback tape, the playback (P) indicators 124 and 132 will be energized and the EVENT-1 and EVENT-2 registers then may be considered to be included within the playback section of console 10. Alternatively, if the position data displayed in these EVENT-1 and EVENT-2 registers represent the edit-in points selected for the recording tape, then record (R) indicators 122 and 130 will be energized and EVENT-1 display register 118 and EVENT-2 register 126 may be considered to be included within the recording section of the console. 
     If SPLIT-OUT selector switch 136 is operated to establish split edit-out points for an agenda-edit operation, then the position data displayed in the EVENT-1 and EVENT-2 display registers represent the edit-out points selected for the recording tape (which will be indicated by the energization of record indicators 122 and 130). As before, EVENT-1 register 118 and EVENT-2 register 126 may be considered to be included in the recording section of console 10. 
     An indicator, similar to those described above, is associated with SPLIT-OUT selector switch 136 and is adapted to be energized to indicate a split-out mode, and to be extinguished to indicate a split-in mode. The position data in the EVENT registers thus may be recognized as representing split-out or split-in edit points, respectively. 
     It will also be described below that the event display registers may be used as supplemental registers to display, or store, additional edit-in and edit-out points for either the playback or recording tape, in order to enable an operator to switch quickly from one to another of such points during an edit operation. This feature becomes extremely useful when an operator has determined that two or more points, such as edit-in points, might be used in the actual edit operations, yet he must select only one of such points. By storing a plurality of edit-in points, the operator may preview various ones of such stored edit-in points easily and quickly, thus assisting him in his selection. 
     The upper portion of the data handling section of console 10 also is provided with a RELAY-1 switch 138 and a RELAY-2 switch 140. Each of these RELAY switches may be constructed as a push-button switch and may be provided with an associated indicator, such as a lamp that is disposed in the same housing therewith. When operated, the associated indicator is energized. The purpose of these RELAY switches is to actuate, or trigger, an external device, such as a special effects generator, a slow-motion device, and the like, when the particular edit point displayed in the EVENT-1 and EVENT-2 registers, respectively, is attained. For example, if an appropriate external device is coupled to the video editing apparatus, and if the position data in EVENT-1 register 118 represents a particular location on the playback tape (which is indicated by the energization of playback indicator 124), then when the playback tape is advanced to this displayed location, the external device coupled to RELAY-1 switch 138 will be actuated if this switch had been operated. As another example, if the position data in EVENT-2 register 126 represents a particular location along the recording tape (which is indicated by the energization of record indicator 130), then if RELAY-2 switch 140 is operated, the external device coupled thereto will be actuated, or triggered, when the recording tape has been advanced to the location corresponding to the position data in the EVENT-2 register. 
     The lower portion of the data handling section of console 10 is provided with a display register 142, its associated selector switch 144, a numerical keyboard 150, arithmetic operation selector switches 158 and 160, a CLEAR switch 162 and a DURATION switch 164. Display register 142 is referred to herein as a scratchpad register and is adapted to display numerical data derived from the operation of keyboard 150, as well as to display position data. Its associated selector switch 144, designated the SCRX switch, functions in a manner similar to the aforedescribed selector switches 52, 56, 60, 82, 86, 90, 120 and 128. Scratchpad register 142 also is provided with a record (R) indicator 146 and a playback (P) indicator 148, these indicators being similar to the aforementioned record and playback indicators described with respect to the upper portion of the data handling section. Thus, if SCRX switch 144 is operated so as to designate scratchpad register 142 as a destination register to receive position data, one of the record (R) and playback (P) indicators 146, 148 will be energized, depending upon whether the position data which is transferred to scratchpad register 142 was derived from a display register in the record or playback section of console 10. SCRX switch 144 has an indicator associated therewith, and if the SCRX switch is operated to designate scratchpad register 142 as the source register, then its associated indicator (e.g. a lamp disposed in the same housing therewith) will provide the aforementioned distinctive indication representing that this switch has been operated as a source switch. 
     Numerical keyboard 150, together with arithmetic operation selector switches 158 and 160, are adapted, when operated, to enable the operator to adjust the position data in any of the aforementioned display registers. In the absence of position data in scratchpad register 142, the operation of numerical keyboard 150 results in the display of the selected numerical data in this display register. When one of the arithmetic operation selector switches 158 and 160 is operated, for example, the &#34;+&#34; switch 158 is operated, scratchpad register 142 is designated as the source register. Then, if any of the selector switches associated with other display registers is operated, its associated display register is designated as the destination register and the numerical data in scratchpad register 142 is summed with the position data in that destination register. This summed data now is displayed in the designated destination register. A similar operation occurs if the &#34;-&#34; switch 160 is operated. In this manner, position data in any of the display registers may be adjusted by arithmetically combining that position data with the numerical data which is &#34;keyed&#34; into scratchpad register 142 from numerical keyboard 150. 
     An arithmetic adjustment of the position data displayed in one display register by the position data displayed in another display register also may be effected, if desired. This is attained by operating a desired one of the selector switches as a source switch, then by operating one of the arithmetic operation selector switches 158 and 160, followed by operating another of the selector switches as a destination switch. This operation results in arithmetically combining the position data in the display register that had been designated as the source register with the position data in the display register that had been designated as the destination register in accordance with whether the &#34;+&#34; switch 158 or the &#34;-&#34; switch 160 had been selected. For example, the position data displayed in EVENT-1 register 118 may be summed with or subtracted from the position data in IN register 50 by operating EVENT-1 switch 120, followed by &#34;+&#34; switch 158 or &#34;-&#34; switch 160, followed by edit-in switch 52. The resultant position data (sum or difference) is displayed in IN register 50. 
     Keyboard 150 also is provided with a LAST EDIT switch 152. This switch, when operated, restores the position data displayed in the respective display registers to that data which was present at the completion of the immediately preceding edit operation. Thus, an operator may recall all previous data to their respective registers so that, if desired, the edit operation may be modified and attempted once again. Such rapid recall of the parameters associated with the preceding edit operation avoids the introduction of errors which might otherwise occur if such data had to be re-established manually. 
     Keyboard 150 also is provided with a LAST X selector switch 154. This switch, when operated, restores the immediately preceding data in the destination register (for example, an IN, OUT or EVENT register) which has been selected. For example, if the operator transfers new position data into IN register 50, the operation of LAST X switch 154 restores the immediately preceding data which had been present in this IN register. Similarly, if EVENT-1 register 118 is selected as a destination register, that is, if position data is transferred thereto, the operation of the LAST X switch restores to this event register the data which had been present therein prior to this latest transfer. 
     Finally, keyboard 150 is provided with an F/TC switch 156. This switch preferably comprises a push-button selector switch having two conditions: (1) to select the time code address as the position data displayed in scratchpad register 142, and (2) to select the frame count (i.e. a count of the control track signals on the tape) as the position data displayed in the scratchpad register. Successive operation of push-button switch 156 is effective to establish one or the other of the two conditions. 
     CLEAR switch 162 is adapted, when operated, to clear all data entries into scratchpad register 142 and, when operated as a source switch, to clear, or &#34;blank&#34; the position data displayed in a display register that is selected as a destination register. DURATION switch 154 is adapted, when operated, to result in the display in the tape timer registers of the difference, or duration, between the edit-in and edit-out points which have been selected for the playback and recording tapes, respectively; and also to display in scratchpad register 142 the total elapsed edit time, i.e. from the first edit-in position to the current, or present position. These displays may be cleared by the concurrent operation of the DURATION and CLEAR switches. 
     The control section of console 10 is comprised of a RECORD switch 170, a STOP switch 172, a PREVIEW switch 174 and a PLAY E-E switch 176. The RECORD switch, when operated, initiates an actual edit operation. That is, the playback and record VTR&#39;s are operated, in response to the actuation of RECORD switch 170, to pre-roll the playback and recording tapes, respectively. Then, once the predetermined pre-roll positions (as selected by PREROLL TIME switch 38) are reached, the respective tapes are advanced toward the edit-in points displayed in IN registers 50 and 80. The information signals on the playback tape then are re-recorded on the recording tape until the respective edit-out positions, as displayed in OUT registers 54 and 84, are reached. 
     STOP switch 172 serves to stop both VTR&#39;s at any time. If, in the course of an actual edit operation, the operator wishes to terminate that operation immediately, operation of the STOP switch will achieve this. PREVIEW switch 174 is adapted, when operated, to provide a preview, or preliminary display, of the edit operation which has been established by the parameters in the respective display registers. A suitable display monitor coupled to the recording VTR will display this previewed edit operation. Thus, when PREVIEW switch 174 is operated, the monitor displays a video picture corresponding to those video signals which had been recorded on the recording tape upstream of the edit-in point, followed by the video picture corresponding to those video signals which are reproduced from the playback tape and re-recorded on the recording tape between the edit-in and edit-out points, followed by the video picture corresponding to those video signals which remain on the recording tape downstream of the edit-out point. If an agenda-edit mode had been selected, the operation of PREVIEW switch 174 effects a display of the split-in and/or split-out edit operation. 
     PLAY E-E switch 176 is adapted to couple an external source of video signals, other than signals which are reproduced by a VTR, to the recording VTR in an edit operation. That is, if a suitable external video source is coupled to the video editing apparatus in place of a playback VTR, then, when PLAY E-E switch 176 is operated, an edit operation is carried out with the signals from this external source being used in place of reproduced video signals. Typically, a color bar generator may be used as as such an external video source, and a color bar pattern derived from this source may be edited onto the recording tape. 
     The operation of console 10 to carry out various types of formats of edits now will be described. In each of the following examples, it is assumed that color frame synchronization has been established, that position data is represented as a time code address, and that a desired amount of reaction trim and pre-roll time had been set by REACTION TRIM and PREROLL TIME switches 36 and 38. 
     Basic Edit 
     In this example, it is assumed that both the video and audio signals which are recorded along a particular length of playback tape are to be transferred concurrently to the recording tape. Initially, the operator actuates MARK ENABLE switch 60, thus designating tape timer register 58 as a source register. When this MARK ENABLE switch is actuated, its associated indicator is energized to provide the steady-state indication that tape timer register 58 has been designated as the source register. The operator now may advance the playback tape by use of JOG switch 70, SHUTTLE switch 72 and speed/direction control 74 until desired information is located. This information may be displayed by a suitable display monitor coupled to the playback VTR. It is appreciated that, in order to locate the desired location of the playback tape, the speed at which the tape is advanced is varied, and it is expected that, as the desired location approaches, the tape speed will be relatively slow. As the tape advances, the time code address displayed in tape timer register 58 correspondingly changes. 
     When the playback tape reaches its desired location such that the information recorded thereon is to be transferred to the recording tape, the operator actuates edit-in switch 52. Upon actuation of this switch, the time code address displayed in tape timer register 58 at the instant that edit-in switch 52 is actuated is transferred into IN register 50. If the playback tape is transported at its normal playback speed, this time code address is adjusted, e.g. decreased, by the predetermined amount set by REACTION TRIM switch 36. Hence, a delay in the operator&#39;s reaction to actuate edit-in switch 52 is compensated. If desired, the operator may now operate STOP switch 64 to arrest the playback tape. 
     The time code address of the edit-out point is established in a similar manner. That is, JOG and SHUTTLE switches 70 and 72, together with speed/direction control 74 are operated until a desired edit-out location is reached. At that time, if the MARK ENABLE switch 60 had been operated to designate tape timer register 58 as a source register, then edit-out switch 56 should be actuated to designate OUT register 54 as the destination register, whereupon the time code address then present in the tape timer register is transferred into this OUT register. 
     In a similar manner, desired edit-in and edit-out locations along the recording tape are determined, and mark enable switch 90, edit-in switch 82 and edit-out switch 86 in the recording section of console 10 are operated so as to set the respective edit-in and edit-out time code addresses into the IN and OUT registers 80 and 84. 
     Normally, the record edit-out point, that is, the position data in OUT register 84, is used to terminate the edit, or signal transfer, operation. However, if the OUT register is blanked, the position data in OUT register 54 is used to terminate the edit operation. 
     If desired, the operator may adjust the respective edit-in and edit-out points by operating keyboard 150 to enter numerical data into scratchpad register 142 and then by operating an arithmetic operation selector switch followed by a register selector switch. For example, the numerical data may be added to the time code address in a selected register by operating &#34;+&#34; switch 158 followed by the appropriate register selector switch. This operation serves to add the quantity in scratchpad register 142 to the quantity in the selected register. Alternatively, the quantity shown in scratchpad register 142 may be subtracted from the time code address in a selected register by operating &#34;-&#34; switch 160 and then operating the appropriate register selector switch. The selected register thus will display the difference between the time code address which previously had been displayed therein and the quantity entered into scratchpad register 142. 
     After adjusting the respective edit-in and edit-out points on the playback and/or recording tape, the information which is to be reproduced from the playback tape may be previewed by operation of PREVIEW switch 66. It is recalled that, when PREVIEW switch 66 is operated, the display monitor coupled to the playback VTR displays a video picture corresponding to black-video-black information. That is, only the video signals which are to be transferred from the playback tape to the recording tape are displayed. Video information surrounding this transferred information is blanked. 
     Similarly, in order to preview the video picture which will be retained on the recording tape, the operator may actuate PREVIEW switch 96. This switch energizes the recording VTR to pre-roll the recording tape and then advance that tape such that the display monitor coupled thereto displays a video picture represented as video-black-video. That is, that portion of the video picture which will be replaced by the information transferred from the playback tape is blanked. 
     If, after previewing the information to be edited from the playback to the recording tape, the operator wishes to make additional adjustments, for example, if he wishes to substitute other information to be edited, this may be attained by operating the mark enable, edit-in and edit-out switches in the manner described above. 
     The overall edit operation may be previewed by operating PREVIEW switch 174 of the control section of console 10. When this switch is operated, both the playback and record VTR&#39;s pre-roll their respective playback and recording tapes by the amount determined by PREROLL TIME switch 38. Then, both tapes are advanced toward their respective edit-in locations. It is recalled that, initially, SYNCHRONIZE lamp 14 flashes as the servo apparatus attempts to synchronize the movement of the playback and recording tapes. Once these tapes are driven in synchronism, that is, once the lock-up condition has been attained, SYNCHRONIZE lamp 14 is energized continuously. While the playback and recording tapes are advanced, the display monitor, such as the monitor that may be connected to the recording VTR, displays the information which is reproduced from the recording tape. Once the edit-in points of the playback and recording tapes are reached, which points are reached simultaneously, the monitor displays the information which is reproduced from the playback tape and which will be re-recorded on the recording tape. Then, when the respective edit-out locations are reached, the monitor once again displays the information which is reproduced from the recording tape. Thus, during this preview operation, the monitor displays the equivalent information (designated &#34;video-video-video&#34; information) which will be provided on the recording tape following the actual edit operation. 
     As mentioned above, the edit-out location that has been selected for the recording tape normally will control the termination of the edit operation, unless OUT register 84 is blanked. That is, the signals which are reproduced from the playback tape will be recorded on the recording tape until the edit-out location represented by the time code address in OUT register 84 is reached. Hence, even if the edit-out point of the playback tape has been passed, the information reproduced from that tape will, nevertheless, be re-recorded on the recording tape until the edit-out location on the recording tape is reached. 
     If the operator now is satisfied with the parameters establishing the edit operation which he has selected, he may operate RECORD switch 170 to initiate the actual edit operation. Thus, the same operation obtains as was discussed with respect to the operation of PREVIEW switch 174, except that now the video signals which are reproduced from the playback tape at the time that the edit-in point on the recording tape is reached will be transferred to the recording tape. 
     If one or more of the parameters which have been selected for the edit operation is erroneous, for example, an edit-out point established for the playback or recording tape preceds its edit-in point, an error indication is provided when a PREVIEW or RECORD switch is operated. This error condition must be corrected before the edit operation (or preview) can continue. 
     After completion of this edit operation, the resultant information which now is recorded on the recording tape may be displayed on the display monitor connected to the recording VTR if PREVIEW switch 174 is operated. As a result of the operation of this switch immediately following the edit operation, the recording VTR is energized to return the recording tape to its edit-in point, and then advance the tape such that all of the edited signals recorded thereon are displayed on the display monitor. 
     Multiple Edit Points 
     When selecting parameters to carry out an edit operation, an operator may wish to select among a plurality of, for example, edit-in or edit-out points. For example, two or more possible edit-in points may be selected preliminarily, and the operator may wish to make a final determination as to which of these points will be used by observing on the display monitor the video picture corresponding to such points. To select these points for the playback tape, for example, the operator actuates mark enable switch 60 and then advances the playback tape by operating JOG and SHUTTLE switches 70, 72 and speed/direction control 74 in the manner described above. 
     As the playback tape is advanced, the operator views the reproduced video picture on the display monitor connected to the playback VTR. When a first desired edit-in point is observed, the operator actuates edit-in switch 52. As discussed above, this transfers the time code address then present in tape timer register 58 into IN register 50. The operator then may continue to advance the playback tape while searching for another possible edit-in point. When the operator observes such a possibly desirable edit-in point, he operates EVENT-1 switch 120 so as to transfer the time code address then displayed in tape timer register 58 into EVENT-1 register 118. 
     Yet another possible edit-in point may be stored in EVENT-2 register 126 by a similar operation, that is, by operating EVENT-2 switch 128. A still further possible edit-in point may be stored in scratchpad register 142 by operating SCRX switch 144. It may be appreciated that, when time code addresses are transferred from tape timer register 58 in the playback section play (P) indicators 124, 132 and 148 associated with display registers 118, 126 and 142, respectively, are energized. 
     A comparison of the video picture which would result from each of these selected edit-in points now may be made as follows. With the first edit-in point stored in IN register 50, the operator may actuate PREVIEW switch 66, thereby previewing the video picture commencing from this edit-in point. Then, after arresting the playback tape by operating STOP switch 64, the operator may transfer the edit-in point now stored in EVENT-1 register 118 into IN register 50. It is appreciated that this transfer is attained by first operating EVENT-1 switch 120, thus designating display register 118 as the source register, and then operating edit-in switch 52, thereby designating IN register 50 as the destination register. The operator now may operate PREVIEW switch 66 to preview the video picture which commences from the edit-in point which now has been transferred into display register 50. 
     After viewing this previewed video picture, the original time code address may be prepared to IN register 50 by operating LAST X switch 154 of keyboard 150 in the data handling section of console 10. Then, the video picture commencing with the edit-in point stored in EVENT-2 register 126 may be previewed by transferring this edit-in point into IN register 50 in a manner similar to that described above with respect to the transfer of position data from display register 118 into display register 50. After previewing this video picture, the operator again may restore the original time code address into IN register 50 by operating LAST X switch 154. If desired, the edit-in point stored in scratchpad register 142 may be transferred to IN register 50, and then the video picture commencing at this edit-in point may be previewed. 
     After previewing the respective video pictures established by the aforementioned edit-in points, the operator may select the desired edit-in point by transferring such point to IN register 50. 
     A similar operation may be carried out to select a desired edit-out point from a plurality of selected edit-out points which may be stored temporarily in display registers 118, 126, and 142. In addition, although the foregoing has described the manner in which a particular one of plural possible edit points may be selected for the playback tape, it should be appreciated that a similar operation can be carried out in order to select appropriate edit points for the recording tape. 
     It is recognized that, when position data is transferred from one display register to another, the data is not erased from the source register. Thus, the operator can reconstruct or arrange various edit operations as he desires, merely by selecting appropriate edit points from such stored data. 
     Furthermore, by energizing the appropriate playback (P) or record (R) indicators associated with the EVENT and scratchpad registers, the operator is kept apprised of the source of such data. That is, the position data in these registers may be transferred from or to the IN and OUT registers in either the playback or record section of console 10. To avoid confusion in transferring such position data, the record and playback indicators remind the operator of the source of such displayed data. Once the appropriate edit-in and edit-out points have been finalized, as discussed above, the overall edit operation may be previewed by operating PREVIEW switch 174. This edit operation then may be carried out by operating RECORD switch 170. If an erroneous parameter has been selected, an error condition indication is provided, which error condition must be corrected to enable the edit operation to proceed. 
     Agenda-Edit Mode 
     This mode will best be understood by the following description of some examples of an agenda-edit operation. 
     Let it be assumed that, after carefully reviewing the playback tape, the operator wishes to establish an edit-in point for the video signals, the audio signals on the first audio track (A-1) and the audio signals on the second audio track (A-2) when the recording tape arrives at time code addresses A, B and C, respectively. This is referred to as a split-in edit and, when initiated, results in the re-recording of the video signals from point A to the edit-out point, the re-recording of the A-1 audio signals from the point B to the edit-out point and the re-recording of the A-2 audio signals from point C to the edit-out point. 
     To establish such split-in edit points, the operator must transfer time code address A into IN register 80, time code address B into EVENT-1 register 118 and time code address C into EVENT-2 register 126. The manner in which these time code addresses are transferred into these respective registers has been described above. Once the appropriate time code addresses have been stored in these display registers, signal selector switches 112, 114 and 116 are operated in the following manner. 
     First, video (V) switch 112 is actuated. The indicator associated with this actuated video switch then flashes, indicating that switch 112 has been operated and that it now is necessary to associate this switch with the time code address displayed in a suitable one of registers 80, 118 and 126. Since time code address A is in IN register 80, and since this is the location at which the video signals are to be transferred, edit-in switch 82 now is operated. Upon operation of this edit-in switch, the indicator associated with video (V) switch 112 is energized to its steady state. It is recalled that respective indicator lamps are provided at the upper and lower halves of switch 112. Both indicator lamps in V switch 112 are energized so as to apprise the operator that the video signals will be transferred from the playback tape to the recording tape when the recording tape reaches the edit-in point A, now stored in display register 80. 
     If A-1 switch 114 now is operated, the indicator lamps associated therewith flash to apprise the operator that this switch has been actuated. It is recalled that he audio signals on the first audio track of the playback tape are to be transferred onto the recording tape when the recording tape reaches edit-in point B. This edit-in point is stored in EVENT-1 register 118, and EVENT-1 switch 120 now should be operated. When the EVENT-1 switch is operated, the indicator associated with the upper half of A-1 switch 114 is energized, thus indicating that the audio signals on the first track of the playback tape will be transferred at a later edit-in point than has been selected for the transfer of the video signals. 
     Finally, A-2 switch 116 is operated, resulting in the flashing of its associated indicators. When EVENT-2 switch 128 is actuated, the indicator associated with the lower half of this A-2 switch is energized. Hence, when the recording tape reaches edit point C, now stored in EVENT-2 register 126, the audio signals which are recorded in the second audio track on the playback tape are transferred, or re-recorded onto the recording tape. Once these split edit-in points A, B and C have been selected and associated with switches 112, 114 and 116, this split-in edit mode may be previewed by operating PREVIEW switch 96 in the recording section of console 10. Operation of this PREVIEW switch actuates the recording VTR to pre-roll the recording tape an amount determined by PREROLL TIME switch 38. Then, the recording tape is advanced, and the respective edit-in points are displayed on the display monitor. 
     Although the foregoing has explained the establishment of a split-in agenda-edit mode in which the video and respective audio signals are transferred when the recording tape reaches its split edit-in points, the split edit-in mode can be carried out by selecting split edit-in points for the playback tape, whereupon the respective video and audio signals will be re-recorded when this playback tape reaches its split-in points. Thus, and analogous to the aforedescribed example, time code address A&#39; on the playback tape may be transferred from, for example, tape timer register 58 into IN register 50, time code address B&#39; may be transferred from this tape timer register into EVENT-1 register 118 and time code address C&#39; may be transferred from this tape timer register into EVENT-2 register 126. The manner in which such time code addresses are transferred into these respective display registers has been described above. 
     Assuming that the video signals, followed by the audio signals on the first audio track, followed by the audio signals on the second audio track are to be transferred, in this order, so as to be recorded on the recording tape when the playback tape reaches edit-in points A&#39;, B&#39; and C&#39;, respectively, the operator first operates video switch 112, resulting in the flashing of the indicators associated with this switch, and then operates edit-in switch 52. This results in steady-state energization of the indicators associated with the upper and lower halves of the video switch. The operator then actuates the A-1 switch 114, resulting in the flashing of the indicators associated with this switch. If EVENT-1 switch 120 next is actuated, the indicator associated with the upper half of the A-1 switch is energized in its steady-state. Finally, the A-2 switch 116 is operated, resulting in the flashing of its associated indicators, followed by the operation of EVENT-2 switch 128. This effects the steady-state energization of the indicator associated with the lower half of the A-2 switch. 
     As a result of the foregoing operation, video signals will be transferred from the playback tape to the recording tape when the former reaches its time code address A&#39;; audio signals will be transferred from the first audio track when the playback tape reaches its time code address B&#39;; and audio signals will be transferred from the second audio track when the playback tape reaches its time code address C&#39;. 
     If it is assumed that the desired edit-in point for the recording tape is displayed in IN register 80, and if it is assumed that a suitable edit-out point is displayed in at least OUT register 84, then a split-in agenda-edit operation can be previewed. Upon operation of PREVIEW switch 174 of the control section of console 10, both the playback and recording tapes are pre-rolled as discussed above. Then, the tapes are advanced until the selected edit-in point is reached, corresponding to edit-in point A&#39; for the playback tape. At that time, the video signals are reproduced from the playback tape. It is recognized that the audio signals are not yet reproduced from the playback tape until that tape reaches its edit-in points B&#39; and C&#39;. When time code address B&#39; is reached, audio signals are reproduced from the first audio track of the playback tape. Similarly, when the playback tape reaches time code address C&#39;, audio signals are reproduced from the second audio track thereon. Hence, the split-in edit operation is previewed. 
     The video and audio signals now reproduced from the playback tape continue until the recording tape reaches the edit-out point displayed in OUT register 84. At that time, the previewed agenda-edit operation is terminated. 
     If the operator is satisfied with this split-in agenda-edit mode, RECORD switch 170 may be operated so as to effect an actual edit operation in accordance with the aforedescribed split-in operation. Thus, a video scene will be inserted on the recording tape, commencing from edit-in point A&#39;, followed by inserted audio signals on the first and second audio tracks at edit-in points B&#39; and C&#39;, respectively. This means that the audio signals which had been recorded on the recording tape prior to edit-in points B&#39; and C&#39; will remain thereon. During a broadcast of these edited signals, the inserted scene will be accompanied by audio information which had been associated with the excised scene, that is, the scene which has been replaced. 
     Operation of PREVIEW switch 174 or RECORD switch 170 also initiates an error-check operation, described below. If one or more parameters which have been selected for the edit operation are not enabling therefor (e.g. an edit-in or edit-out point for one of the video or audio signals has been omitted, or an intermediate edit-in point does not lie between the first edit-in point and the edit-out point), an error condition is indicated. This error condition must be corrected in order to proceed. 
     The foregoing has described a split-in agenda-edit mode of operation wherein the initiation of the re-recording of video and audio signals is staggered, or &#34;split&#34;. A similar split-out operation can be established, if desired. Moreover, the agenda-edit operation may be constituted by a split-in and also by a split-out edit mode. To establish a split-out edit operation, SPLIT-OUT switch 136 is operated, and then the setting of time code addresses in the respective OUT and EVENT registers is carried out. For example, let it be assumed that, when the recording tape reaches time code address A&#34;, the transfer of video signals from the playback tape should terminate. Similarly, let it be further assumed that when the recording tape reaches time code addresses B&#34; and C&#34;, the transfer of audio signals from the first and second tracks, respectively, of the playback tape should terminate. 
     Time code address A&#34; is transferred into OUT register 84 and time code addresses B&#34; and C&#34; are transferred into EVENT registers 118 and 126, respectively. It is appreciated that such time code addresses A&#34;, B&#34; and C&#34; are transferred from tape timer register 88, this register being designated by mark enable switch 90 as a source register. Once these time code addresses have been stored in the aforementioned display registers, the operator first actuates video switch 112, thus causing the indicators associated therewith to flash, and then operates edit-out switch 86, resulting in the steady-state energization of the indicators associated with both halves of the video switch. This establishes time code address A&#34; as the edit-out point for the video signals. 
     In similar manner, A-1 switch 114 is actuated, thus causing the indicators associated therewith to flash, and then EVENT-1 switch 120 is operated, resulting in the steady-state energization of the indicator associated with the upper half of the A-1 switch. The edit-out point B&#34; now is established as the edit-out point for the audio signals which are recorded on the first track. 
     Finally, A-2 switch 116 is actuated, thereby causing the indicators associated therewith to flash, and then EVENT-2 switch 128 is operated, resulting in the steady-state energization of the indicator associated with the lower half of this A-2 switch. Hence, time code address C&#34; is established as the edit-out point for the audio signals on the second audio track. 
     During a actual edit operation, video and audio signals will be transferred from the playback tape to the recording tape, commencing with the edit-in points. It is recalled that, if desired, such edit-in points may be &#34;split&#34; in the manner discussed above. When the recording tape reaches edit-out point B&#34;, audio signals in the first audio track no longer are re-recorded thereon. When the recording tape next reaches edit-out point C&#34;, audio signals no longer are re-recorded in the second audio track. Finally, when the recording tape reaches edit-out point A&#34;, the split-out operation is completed. 
     Although EVENT registers 118 and 126 are capable of displaying either edit-in or edit-out points, both a split-in and a split-out operation may occur, as described above. If SPLIT-OUT switch 136 is operated, then the position data displayed in the EVENT registers represents the edit-out points. If the SPLIT-OUT switch 136 is not operated, then the position data displayed in EVENT registers 118 and 126 represent the edit-in points. An indicator associated with SPLIT-OUT switch 136 provides a suitable indication to apprise the operator of the display of edit-in or edit-out points. In either mode, it is appreciated that the record (R) and playback (P) indicators 122, 130 and 124, 132 represent the source of the position data displayed in these EVENT registers. 
     In the foregoing discussion, it has been assumed that switches 112, 114 and 116 are actuated by the operator in the order of the V switch, followed by the A-1 switch, followed by the A-2 switch. It should be appreciated that these switches may be actuated in any order desired. In a split-in agenda-edit mode, the signal selector switch which is selected to be associated with the time code address displayed in the IN register, is identified by the energization of the indicators associated with the upper and lower halves of this switch. The signal selector switch which is selected to be associated with the time code address displayed in EVENT-1 register 118, is identified by the energization of the indicator which is associated with the upper half of this switch. Finally, the signal selector switch which is selected to be associated with the time code address in EVENT-2 register 126, is identified by the energization of the indicator associated with the lower half of this switch. It will be recognized that the first edit-in point is displayed in the IN register, and the next following edit-in points are displayed in the EVENT-1 and EVENT-2 registers. The particular video and audio signals that are to be transferred at these respective edit-in points are determined by the corresponding V, A-1 and A-2 switches that are associated therewith. 
     A similar explanation is applicable to a split-out agenda-edit mode which is established by operating SPLIT-OUT switch 136. In the interest of brevity, and since additional explanation of such a split-out agenda-edit mode is duplicative, further description is not provided. 
     The foregoing has described a so-called three-way agenda-edit operation. If desired, a two-way agenda-edit mode may be established merely by actuating two of switches 112, 114 and 116 concurrently. For example, in a split-in mode, video switch 112 may be actuated first so as to be associated with the first edit-in point. Then, A-1 switch 114 and A-2 switch 116 may be actuated such that the indicators associated with both switches flash concurrently. Depending upon which of the EVENT switches is operated, switches A-1 and A-2 both will be associated with the time code address displayed in the corresponding EVENT register. Hence, the indicators associated with the upper half of both of switches 114 and 116 will be energized if EVENT-1 switch 120, for example, is operated. This means that the audio signals on both the first and second audio tracks will be transferred when the second-selected edit-in point, displayed in the EVENT-1 register, is reached. In a one-way, or simple edit mode, the indicators associated with both the upper and lower halves of the V, A-1 and A-2 switches all are energized to indicate that all three signal selector switches are associated with the selected edit-in point. Separate actuation of these signal selector switches in a simple edit mode is not necessary. 
     If it is desired that either the video or audio signals should not be re-recorded, the switch or switches which are associated with signals that should be recorded first are operated to establish the appropriate edit-in points. Then, the remaining switches should be actuated, thus causing the indicators associated therewith to flash, and then actuated again to extinguish such indications and avoid the assignment of a time code address to those switches. During an edit operation for this condition, only the signals associated with the assigned switches will be transferred from the playback tape to the recording tape at the selected edit-in points. The signals associated with the unselected switches will not be transferred. 
     Thus, it may be seen that various combinations of split edit-in and split edit-out points may be determined merely by operating the video and audio switches 112, 114 and 116 and the edit-in and EVENT switches to establish the order desired by the operator, thereby selecting one or more time code addresses at which the video and audio signals are transferred from the playback tape to the recording tape. A common time code address may be selected for those switches which are operated concurrently or, in a simple edit mode, for all three switches when desired edit-in and edit-out points are selected (as by operating the selected edit-in and edit-out switches). As is seen, the edit-in and edit-out points may be selected on either the playback or the recording tape, depending upon which tape is chosen to derive the respective time code addresses. 
     Error Indications 
     As mentioned above, indications of one or more erroneous parameters which have been selected for an edit operation are provided when the operator operates the PREVIEW or RECORD switches. Furthermore, the selected edit cannot be previewed or carried out until the erroneous parameter is cleared. As will be described, the error indication identifies the probable source of the error condition, thereby apprising the operator of the general type of corrective action which would be necessary. 
     When an error condition is detected, the indicator associated with CLEAR switch 162 is flashed. Also, if erroneous position data has been selected for the edit operation, the indicator associated with the display register which contains that erroneous position data is flashed. If the detected error condition is attributed to an improper or incomplete agenda-edit selection, the indicators associated with V, A-1 and A-2 switches are flashed. Some examples of typical error conditions and error indications are set out below; a detailed explanation of this feature is described in conjunction with FIGS. 14A-14D. 
     Let it be assumed that a simple edit is to be performed. If the selected edit-out point for either the playback or recording tape, as represented by the position data in OUT register 54 or OUT register 84, precedes the selected edit-in point, as represented by the position data in IN register 50 or IN register 80, this error condition is detected in response to the operation of PREVIEW switch 174 or RECORD switch 170. The indicator associated with CLEAR switch 162 is flashed and, moreover, the indicator associated with either edit-out switch 56 or edit-out switch 86 is flashed to apprise the operator that the selected edit-out point is erroneous. 
     As another example, an error condition exists if an agenda-edit split-in mode is selected, but one of the video or audio signals is not assigned with an edit-out point. This may occur if, for instance, one of the V, A-1 or A-2 signal selector switches is not operated in conjunction with an edit-out or EVENT switch in the manner described above. When the edit operation is to be previewed or performed, this error condition is indicated by the flashing of the indicator associated with CLEAR switch 162, and by the flashing of the indicators, V, A-1 and A-2. This apprises the operator of the existence of the error condition with the edit-in point agenda or with the edit-out point agenda. 
     As a further example, if the data displayed in the EVENT-1 or EVENT-2 register has not been derived from either the playback or recording tapes, e.g., this data has been derived from keyboard 150 and scratchpad register 142, then the playback (P) and record (R) direction indicators 122, 124, 130 and 132 will not be energized. If this EVENT register is selected for use in establishing a split edit-in or edit-out point, it cannot be determined which tape reaches that point. This error condition is detected in response to the operation of the PREVIEW or RECORD switches, and is indicated by the flashing of the indicator associated with the CLEAR switch, by the flashing of the LED direction indicators adjacent the appropriate EVENT register and by the selective flashing of the indicator associated with the SPLIT OUT switch. Thus, an operator is apprised that the edit-in or edit-out represented by the data in the particular EVENT register has not been derived from either the playback or recording tape. Similarly, if the EVENT-1 or EVENT-2 register is selected for use in a split-in or split-out edit operation, but that register has been &#34;blanked&#34; (i.e. the position data displayed therein has been cleared, or erased), then the indicator associated with that register is flashed. The operator thus observes the flashing of the indicator associated with the CLEAR switch, the flashing of the indicator associated with the appropriate EVENT register, and the selective flashing of the indicator associated with the SPLIT OUT switch (representing blanked position data for the split-in or split-out mode, respectively). 
     As yet another example, if an agenda-edit operation is selected, but the position data in neither of IN registers 50 and 80 is assigned as an edit-in point, this condition is detected as an error condition in response to the operation of the PREVIEW or RECORD switches, and the indicators associated with all of the V, A-1 and A-2 switches are flashed. Also, the indicator associated with the SPLIT OUT switch is not flashed, thereby apprising the operator that none of the video and audio signals have been assigned with the first edit-in point. Likewise, if the position data in neither of OUT registers 54 and 84 is assigned as an edit-out point, the condition is detected as an error condition in response to the operation of the PREVIEW or RECORD switches, and the indicators associated with all of the V, A-1 and A-2 switches are flashed and the indicator associated with the SPLIT OUT switch as flashed. 
     As an additional example, an error condition is detected if any of the edit-in or edit-out points represented by the position data in the EVENT-1 and EVENT-2 registers for an agenda-edit mode do not lie between the edit-in point represented by the position data in IN register 80 and the edit-out point represented by the position data in OUT register 84. This error condition is indicated by the flashing of the indicator associated with the EVENT register which displays the erroneous position data, by the selective flashing of the indicator associated with the SPLIT OUT switch, and by the flashing of the CLEAR switch. 
     In addition to detecting and indicating errors of the type discussed in the foregoing examples, the error detecting arrangement inhibits an actual or preview edit operation from being carried out until the detected error condition is corrected. Furthermore, and as will be described in greater detail below, a hierarchy of possible error conditions are checked in predetermined order. The continued error checking operation is suspended when an error condition is detected, until that condition is corrected. Upon subsequent operation of the PREVIEW or RECORD switches, the error checking operation resumes. 
     GENERAL DESCRIPTION OF THE SYSTEM ELECTRONICS 
     Turning now to FIG. 2, there is illustrated a block diagram of the overall video editing system comprised of console 202, separate VTR&#39;s 204 and 206, a central processing unit (CPU) 208 and display monitors 210 and 212 coupled to VTR&#39;s 204 and 206, respectively. Console 202 may include the selector switches, display registers, controls and keyboard, all discussed hereinabove with respect to console 10 of FIG. 1. In addition, and as will be described below, console 202 also includes particular electronics for energizing the respective display registers and indicator lamps. In a preferred embodiment, each display register is comprised of seven-segment numerical display elements which may be constituted by light emitting devices (LED&#39;s), liquid crystal displays (LCD&#39;s), or the like. The manner in which such numerical displays are energized will be described in greater detail below. 
     Console 202 also is provided with energizing circuitry for energizing the particular indicators, such as the respective indicator lamps associated with the selected switches, as well as the record (R) and playback (P) LED indicators associated with the EVENT and scratchpad registers. 
     Console 202 is coupled to VTR&#39;s 204 and 206, respectively, and is adapted to receive position data from these VRT&#39;s. Interface and control circuitry may be provided between each of these VTR&#39;s and console 202 for the purpose of assuring that proper time code addresses and frame, or control track signals, are supplied to the console, and particularly to tape timer registers 58 and 88. A detailed description of such interface and control circuitry is described in copending applications Serial Nos. (Serial No. 139702). The disclosure of such copending applications is incorporated herein by reference. 
     Console 202 and VTR&#39;s 204 and 206 are coupled to CPU 208. Although not shown herein, it should be appreciated that interface, or communicating circuitry, is provided between the console and the CPU and also between the VTR&#39;s and the CPU. Position data in the form of time code addresses and frame, or control track signals, are supplied from each of the VTR&#39;s to the CPU. Thus, the CPU is provided with the same position data as console 202. 
     A bi-directional data bus couples console 202 and CPU 208 to each other. This data bus serves to supply data derived from the console to the CPU, and also serves to supply to the console data which is transmitted from the CPU. For example, whenever a selector switch or control element in console 202 is operated, a coded representation thereof is supplied to CPU 208. Similarly, whenever the energization of an indicator display register of the console is to be updated, such as during a display register data transfer operation, data is transmitted from CPU 208 to console 202. Still further, the operation of the circuitry included in console 202 and CPU 208 may be synchronized by a system clock, and appropriate timing information is transferred between the console and CPU. 
     CPU 208 is comprised of a microprocessor, such as a Model 8080 microprocessor, manufactured by Intel Corporation of California, together with associated memory and appurtinent devices which commonly constitute central processing units. CPU 208 serves, in addition to updating the data displayed on console 202, to control the operation of VTR&#39;s 204 and 206 to effectuate the edit operation that has been selected in the manner described hereinabove with respect to console 10 of FIG. 1. For this purpose, CPU 208 supplies control signals to these VTR&#39;s. It is appreciated that, although not shown in FIG. 2, suitable interface circuitry is provided between the CPU and each of VTR&#39;s 204 and 206. To this effect, the CPU may supply speed and direction control signals to the VTR&#39;s, start and stop control signals and record/playback control signals. The latter control the transfer of information from the playback VTR, such as VTR 204, to the recording VTR, such as VTR 206. 
     To carry out an edit operation, console 202 is operated in the manner discussed hereinabove with respect to FIG. 1 to supply CPU 208 with data representative of the particular operations which have been selected by the operator. CPU 208 responds to this data to control VTR&#39;s 204 and 206 so as to, for example, advance the playback and recording tapes to enable the operator to select particular video pictures, or scenes, which should be edited. Such scenes are, of course, displayed on display monitors 210 and 212 as the playback and recording tapes are advanced. 
     As the respective tapes are transported, position data associated therewith, that is, position data derived from the reproduced time code addresses and control track signals, are supplied to console 202 and to CPU 208. This position data serves to update tape timer registers 58 and 88 (FIG. 1) in a manner described in greater detail below. This data update is carried out automatically and without specific action on the part of the operator. When the commencement of a particular scene recorded on the playback tape, and suitable for re-recording onto the recording tape, is reached, mark enable switch 60 is operated; and console 202 supplies a coded representation of that switch to CPU 208. The CPU recognizes this coded representation as a source switch. Then, when edit-in switch 52 is operated, console 202 transmits a coded representation thereof to CPU 208. This coded representation is recognized as a destination switch, and the CPU now transmits to console 202 the position data which had been displayed in tape timer 58 at the time that the edit-in switch was operated, which position data now is displayed in IN register 50. More particularly, the numeric display elements which constitute the display register are suitably energized with this position data. CPU 208 also stores this position data in a particular location for use in controlling the edit operation of the playback and recording tapes. 
     The foregoing communication of data between console 202 and CPU 208 is carried out whenever a selector switch on the console is operated, whenever the data displayed by a display register on the console is to be updated, such as in response to a register-transfer operation, and whenever arithmetic operations (such as of the type discussed above with respect to FIG. 1) are to be carried out. 
     Thus, the selected parameters for carrying out an edit operation are generated from console 202 and supplied to CPU 208. Indications of such parameters are returned to the console by the CPU so as to apprise the operator thereof. CPU 208 thus is supplied with sufficient data to control the selected edit operation, to detect various error conditions, and to control error indications, such as those discussed in the examples described above. 
     If a PREVIEW switch, such as PREVIEW switch 66, is operated, a coded representation of this switch is transmitted to CPU 208 from console 202. In response to the actuation of this switch, CPU 208 supplies control signals to VTR 204, resulting in a preview operation, discussed above. The video picture displayed on display monitor 202 is blanked until the scene selected for re-recording. That is, the scene defined by the edit-in and edit-out points stored in CPU 208, is reached. Arrival of the playback tape at the selected scene is detected by CPU 208, for example, by comparing the position data supplied thereto from the VTR with the position data representing the selected edit-in point, and the CPU now controls the reproducing electronics of this VTR such that the selected scene is displayed on display monitor 210. The CPU detects when the playback tape is advanced to the selected edit-out point, whereupon monitor 210 is blanked. Thus, display monitor 210 displays a black-video-black picture corresponding to the scene which has been selected for re-recording. 
     CPU 208 controls the operation of VTR 206 in a similar manner in the event that, for example, PREVIEW switch 96 is operated. 
     If RECORD switch 170 in the control section of the console is operated so as to initiate an actual edit operation, a coded representation of this switch is transmitted to CPU 208 from console 202. The CPU then controls both VTR&#39;s 204 and 206 to carry out the edit operation, described above. Thus, the playback and recording tapes both are pre-rolled by the preselected pre-roll amount, and then both tapes are advanced. During the advance of these tapes, the servo apparatus included in the VTR&#39;s is controlled by CPU 208 to effect a lock-up condition of the playback and recording tapes, whereby such tapes now are transported in synchronism with each other. The position data supplied to CPU 208 from VTR&#39;s 204 and 206 is compared to the respective edit-in points stored in the CPU. When these tapes arrive at their respective edit-in points, the CPU actuates the recording electronics in VTR 206 such that the information that is reproduced by VTR 204 from the playback tape now is recorded on the recording tape. It is appreciated that the re-recording of information may be carried out in a simple edit mode or in a split-in edit-agenda mode, discussed above. The re-recording of information on the recording tape continues until the CPU detects that the selected edit-out point has been reached. At that time, the recording electronics in VTR 206 are disabled, thus completing the edit operation. It is appreciated that the edit-out point may be a simple point or may be split-out points, discussed above. If an error condition is detected, however, the actual edit operation is inhibited until that error condition is corrected. 
     The foregoing has been a general description of the manner in which the apparatus illustrated in FIG. 2 carries out an insert-edit operation. If ASSEMBLE MODE switch 110 (FIG. 1) had been operated, the illustrated apparatus effects an assemble-edit operation wherein the scene selected from the playback tape is recorded in following relation to the last scene that had been recorded on the recording tape, and new time code signals and control track signals also are recorded. That is, the information from the playback tape is transferred to the recording tape when the latter reaches its selected edit-in point. Typically, in an assemble edit operation, the transferred scene merely is added, or &#34;assembled&#34; to those video signals already present on the recording tape. This differs from the &#34;insertion&#34; of a video scene into a selected block on the recording tape in accordance with the insert edit mode. It may be appreciated that in an insert edit operation, the edit-out point which has been selected for the recording tape is the controlling factor in terminating the edit operation unless, of course, an edit-out point has not been selected for the recording tape, whereupon the edit-out point which has been selected for the playback tape terminates the edit operation. However, in an assemble edit operation, it is the edit-out point that has been selected for the playback tape which is the controlling factor in terminating the edit operation. 
     Particular electronic circuits which are provided in console 202 and in the interface, or communicating electronics, between this console and CPU 208 now will be described with reference to FIGS. 3-11. 
     Data Transmitting Electronics 
     Turning now to FIG. 3, there is illustrated a block diagram of the electronics utilized to transmit data from console 202 to CPU 208. It is appreciated that this data represents the particular switches that may be operated to carry out a data transfer operation, an arithmetic adjustment operation, or an operation for controlling tape movement, such as a playback, preview, cue, record, or other similar operation. The data transmitting electronics is comprised, generally, of a keyboard matrix encoder 304, a code converter 306, a parallel-to-serial converter 308, a serial-to-parallel converter 312 and a bi-directional buffer 328. Keyboard matrix encoder 304 may be of a conventional type, such as Model AY-5-3600 PRO and is provided with a plurality of inputs, each adapted to receive a voltage. The keyboard matrix encoder serves to produce an encoded signal, such as a parallel-bit digital signal, encoded in a manner corresponding to the particular input upon which an input voltage has been received. The inputs of keyboard matrix encoder 304 are connected to respective ones of switches 302. These switches correspond to the selector switches provided on console 10 of FIG. 1. Thus, depending upon which of these switches is operated, voltages are applied to the keyboard matrix encoder at the particular inputs which are connected to this operated switch. If the selector switches are, for example, push-button switches, then pulse signals are supplied to respective inputs of the keyboard matrix encoder in response to the operation of that push-button switch. 
     Typically, the encoded output produced by keyboard matrix encoder 304 differs from the particular code to which CPU 208 is responsive. Code converter 306 is coupled to the keyboard matrix encoder and is adapted to produce a compatible encoded representation of the particular switch 302 which has been operated. That is, code converter 306, which may comprise a programmable read-only memory (PROM), is adapted to convert the plural-bit digital signal received from keyboard matrix encoder 304 into a suitable coded signal. 
     Code converter 306 is provided with a plurality of outputs, for example, eight outputs to supply an 8-bit signal, coupled to an equal number of inputs of parallel-to-serial converter 308. This parallel-to-serial converter is included within a so-called universal synchronous/asynchronous receive/transmit (USART) device, such as Model AY 5-1013A. This device serves to convert the parallel-bit coded signal received from code converter 306 into a serial-bit signal. For this purpose, parallel-to-serial converter 308 includes a clock signal input connected to a clock signal generator 310, referred to herein merely as a clock. Clock 310 is adapted to generate successive timing signals which are used to serially transmit the coded signal received by the parallel-to-serial converter. Clock 310 may include an oscillator and various timing circuits in order to produce a clock signal of desired frequency. 
     The serial-bit coded signal produced at the output of parallel-to-serial converter 308 is supplied to serial-to-parallel converter 312. Converter 312 may be similar to converter 308, and may be included in a section of another universal synchronous/asynchronous receive/transmit device. Clock 310 is coupled to a clock signal input of converter 312 so as to synchronously receive the serial bits supplied thereto and convert such serial bits to a parallel-bit coded signal. Converter 312 is provided with a plurality of outputs coupled to an internal data bus 314, this internal data bus serving to connect serial-to-parallel converter 312 to bi-directional buffer 328. Converter 312 also includes an output 316 which is adapted to be provided with a signal, for example, a binary &#34;1&#34;, when the converter has received eight successive bits from parallel-to-serial converter 308. For the purpose of the present discussion, it will be assumed that a digital signal formed of eight bits is a word or a byte. Thus, when serial-to-parallel converter 312 receives a complete word, output 316 thereof is provided with a binary &#34;1&#34;. 
     Serial-to-parallel converter 312 also is provided with a gate input connected to receive a gating signal derived from CPU 208. For convenience, and for consistency with the detailed schematic diagrams of FIGS. 14A-14E, this gating signal is designated the I/OR45 signal. In response to this gating signal, supplied to serial-to-parallel converter 312 via an input lead 326, the parallel-bit word of this converter is supplied to internal data bus 314. 
     Output 316 of serial-to-parallel converter 312 is coupled to the set input S of a flip-flop circuit 318. The reset input R of this flip-flop circuit is coupled to lead 326 to receive the I/OR45 gating signal. When flip-flop circuit 318 is set in response to the binary &#34;1&#34; supplied to its set input S, a signal indicative of the set state thereof is supplied to an interrupt handler circuit 320. This circuit is of conventional construction, one embodiment of which is an interrupt handler Model 8259. As is known, a CPU communicates with an external, or peripheral device, in response to &#34;interrupt requests&#34;. That is, when data is to be transmitted to the CPU from such a device, an interrupt request first is supplied to the CPU. Once the CPU acknowledges this interrupt request, it embarks upon an appropriate programmed routine so as to receive the data for which the interrupt request has been made. Interrupt handler 320 is adapted to receive a plurality of interrupt requests, one of which is the signal supplied thereto when flip-flop circuit 318 is triggered to its set state. The interrupt handler functions to select appropriate requests in accordance with a predetermined order of priority, and to transmit coded representations of each such request to the CPU. Thus, when flip-flop circuit 318 supplies interrupt handler 320 with an interrupt request signal, a coded representation of that interrupt request signal is transmitted to the CPU. Interrupt handler 320 additionally includes an acknowledge input terminal coupled to lead 324 for receiving an acknowledgement from the CPU that the latter has received and is processing the interrupt request transmitted thereto by the interrupt handler. This interrupt request acknowledge signal is designated and INTA. When the CPU enters its programmed interrupt routine and is in condition to respond to the particular interrupt signal that has been transmitted in response to the setting of flip-flop circuit 318, the I/OR45 is derived from the CPU and supplied to lead 326 so as to reset this flip-flop circuit and also to enable, or gate, the word from serial-to-parallel converter 312 onto internal data bus 314. 
     Bi-directional buffer 328 is conventional, one embodiment of which is a Model LS243 buffer. This buffer is adapted to communicate with CPU 208 via a system data bus 332. That is, words, or bytes, may be transmitted from the bi-directional buffer to the CPU, and words may be received by this buffer from the CPU. It may be appreciated, therefore, that internal data bus 314 may be used either as an input data bus or an output data bus, depending upon the direction in which data in transmitted. Similarly, system data bus 332 may comprise an output or an input data bus, depending upon whether data is being transmitted to or received from CPU 208. In the arrangement illustrated in FIG. 3 wherein data is transmitted to CPU 208, internal data bus 314 may be considered to be connected to the inputs of bi-directional buffer 328, and system data bus 332 may be considered to be connected to the outputs of this buffer. In addition, bi-directional buffer 328 is provided with a gate input connected to lead 330 to receive a gating signal derived from the CPU so as to enable the word supplied thereto via internal data bus 314 to be transmitted therefrom to system data bus 332. This gating signal is derived from the aforementioned signal I/OR45 and, for convenience, FIG. 3 illustrates that this gating signal I/OR45 is supplied to lead 330. 
     In operation, when one of switches 302, such as one of the selector switches of console 10 (FIG. 1) is operated, a signal voltage representative thereof is supplied to keyboard matrix encoder 304 at inputs to which the operated switch is connected. The keyboard matrix encoder generates an encoded representation of this operated switch and supplies that representation to code converter 306 whereat it is converted to a particular code that is compatible with CPU 208. It may be appreciated that, if keyboard matrix encoder 304 functions to produce such a compatible code, code converter 306 may be omitted. 
     Code converter 306 supplies a parallel-bit word, corresponding to the particular switch 302 which has been operated, to parallel-to-serial converter 308. Clock signals also are supplied to this converter from clock 310, resulting in a serialized word supplied from this parallel-to-serial converter to serial-to-parallel converter 312. Clock signals also are supplied to this latter converter so as to synchronize the reception of the serialized word. 
     When a complete word has been received by serial-to-parallel converter 312, a binary &#34;1&#34; is provided at output 316 to set flip-flop circuit 318 to its set state. This, in turn, supplies an interrupt request signal to interrupt handler 320. The interrupt handler apprises the CPU that an interrupt request is to be made. The CPU then enters its interrupt program routine and returns the INTA signal to interrupt handler 320 via lead 324. If it is assumed that no other interrupt request signals are supplied to the interrupt handler, or alternatively, the interrupt request signal derived from serial-to-parallel converter 312 exhibits the highest priority, interrupt handler 320 transmits a coded representation of this interrupt request to the CPU. 
     In its interrupt program routine, the CPU responds to this particular interrupt request by returning the I/OR45 signal via lead 326, thereby resetting flip-flop circuit 318 and enabling serial-to-parallel converter 312 to gate the word representing the operated switch 302 onto internal data bus 314. This I/OR45 signal also enables bi-directional buffer 328 to transmit this word from the internal data bus through the buffer onto system data bus 332, thus transmitting this work to CPU 208. Consequently, the identity of the particular switch on console 10 (FIG. 1) which has been operated is transmitted to the CPU. 
     As will be described below, the CPU responds to this received coded representation of an operated switch by transmitting data to the console, resulting in the energization of an indicator associated with a selector switch, or the display of tape position data. 
     Data Receiving Circuitry 
     As mentioned above, CPU 208 responds to the coded representation of the operated switch 302 by returning data to the console electronics. If the switch which has been operated is identified as a source switch, the CPU transmits an indicator control signal, in the form of an indicator data word, so as to actuate the indicator associated with the source switch, thereby informing the operator of the particular switch which has been actuated as the source switch. Alternatively, if the operated switch is identified as a destination switch, the CPU returns an indicator data word to extinguish the energized indicator, and also a plurality of position data words which are used to energize the numerical display elements which constitute the respective display registers. FIGS. 4A and 4B illustrate the apparatus which is used to receive these words from CPU 208 and to use such words to control the respective indicators and numerical display elements. This data-receiving apparatus is comprised of a buffer 416, converters 312 and 308, described previously with respect to FIG. 3, a buffer 420, an address latch circuit 426, a timing counter 438, an address multiplexer 428 and a memory device, preferably a random access memory (RAM)424. The purpose of this apparatus is to receive the data words from the CPU and to store such data words in appropriate addresses in RAM 424. As will be explained below with respect to FIG. 5, respective addresses in RAM 424 correspond to particular indicators and numerical display elements. It is important, therefore, for the proper energization of such indicators and numerical display elements that the appropriate data word be stored in the correct address in the RAM. Accordingly, the CPU precedes each data word with an address word. More particularly, in the embodiment described herein, the CPU transmits an address word followed by an indicator data word and, when position data is transmitted, the CPU transmits an address word followed by a predetermined number of position data words. In most instances, when indicator control signals are transmitted, a single indicator word is transmitted, and this is preceded by a corresponding address word. Similarly, in most instances, a predetermined number (e.g. four) of position data words are transmitted, preceded by a single address word. A general exception to this convention is the transmission of data from the CPU to the console, which data is necessary to update all of the displays and indicators, as may be required when an error condition is detected. 
     As will be described, position data also is transmitted to RAM 424 from the VTR&#39;s. That is, as the playback and recording tapes are transported, the time code addresses and control track signals read therefrom are supplied via apparatus described in copending applications serial numbers 139,748 and 139,702, each filed Apr. 11, 1980 to appropriate addresses in the RAM, thereby updating timer registers 58 and 88 of console 10 (FIG. 1). The circuitry illustrated in FIGS. 4A and 4B is intended to perform this function. 
     Data is not transmitted from the CPU to the apparatus illustrated in FIGS. 4A and 4B until the CPU is supplied with a signal representing that this apparatus is in condition to receive such data. As will become apparent, buffer 416, which is a so-called first-in-first-out (FIFO) buffer, is adapted to receive address data words and position data words which are derived either from the CPU or from the VTR&#39;s. Since data derived from the VTR&#39;s still might be present in buffer 416 at the time that the CPU is conditioned to transmit data thereto, flip-flop circuit 402 and AND gate 404 are provided to produce an enabling signal which apprises the CPU when this buffer is in condition to receive data therefrom. The set input S of flip-flop circuit 402 is connected to receive a signal derived from the CPU representing that data is about to be transmitted therefrom. The reset input R of the flip-flop circuit is adapted to receive a signal representing that the CPU has completed its transmission of data. AND gate 404 includes one input connected to the Q output of this flip-flop circuit and another input connected to a lead 418 for receiving a signal from buffer 416 representing that the contents of this buffer are &#34;empty&#34; and that the buffer is in condition to receive data which may be transmitted by the CPU. The output of AND gate 404 is adapted to produce the enabling signal, whereby the CPU then proceeds with the transmission of data. 
     Multiplexer 406 is provided with two sets of inputs: the A inputs and the B inputs. The A inputs of this multiplexer are coupled to a pre-set address generator 408 which is adapted, when actuated, to supply a first or a second predetermined address to multiplexer inputs A. This address identifies a respective location in RAM 424. The manner in which pre-set address generator 408 is actuated is described in greater detail below with respect to FIG. 10. 
     The B inputs of multiplexer 406 are coupled to internal data bus 314 which, as described above, is connected to bi-directional buffer 328 whose inputs are coupled to system data bus 332 to receive words from CPU 208. When this bi-directional buffer is intended to transmit data to the CPU, the gate signal supplied to its gate input via lead 330 conditions this buffer to transmit data from internal data bus 314 to system data bus 332. However, the gate signal supplied to the gate input of bi-directional buffer 328 also conditions this buffer to receive data from the CPU such that data supplied to system data bus 332 is transferred to internal data bus 314. The gate signal supplied to lead 330 thus functions as a transmit/receive control signal derived from CPU 208. That is, when data is to be transmitted to the CPU, this control signal functions to condition the bi-directional buffer to transmit data to the system data bus. However, when the CPU is to transmit data to the console, the control signal supplied to lead 330 conditions the bi-directional buffer to receive data from the system data bus. 
     Multiplexer 406 additionally includes a control input coupled to a lead 410 to receive a multiplex control signal. This multiplex control signal is generated by circuitry described below with respect to FIG. 10. The multiplexer may be a conventional multiplexing circuit, such as Model LS257, whereby the data supplied to its inputs A or inputs B selectively is transmitted therethrough to its outputs. 
     The outputs of multiplexer 406 are coupled to respective inputs of buffer 416. It may be appreciated that the multiplexer and buffer are connected by a plurality of leads such that a parallel 8-bit word may be transferred from the multiplexer to the buffer. Buffer 416 preferably is of the aforementioned FIFO type, one embodiment of which is Model AM2841. Buffer 416 additionally includes an enable input coupled by a lead 412 to receive an enable signal derived from the CPU. The buffer further includes a clock input coupled via lead 414 to receive a clock signal from a suitable timing circuit (not shown). The enable signal supplied to buffer 416 is referred to as the I/OW45 signal and is derived from the CPU when the CPU transmits data to the console. This signal thus is generated during the normal data transmission program routine of the CPU. The outputs of buffer 416 are coupled to respective inputs of parallel-to-serial converter 312, described above with respect to FIG. 3. This converter 312 serves to serialize the parallel 8-bit word supplied thereto from buffer 416 and to transmit this serialized word to serial-to-parallel converter 308. It is appreciated, therefore, that converters 308 and 312 function to transmit data bi-directionally so as to supply data to the CPU from the console electronics and to supply data received from the CPU to the console electronics. 
     As is conventional, serial-to-parallel converter 308 includes a &#34;ready&#34; output adapted to produce a &#34;ready&#34; signal, such as a binary &#34;1&#34;, when a complete word has been received from parallel-to-serial converter 312. This &#34;ready&#34; signal is applied via a lead 430 to a counting circuit 432. 
     The outputs of serial-to-parallel converter 308 are coupled to respective inputs of buffer 420 such that the converter supplies a parallel 8-bit word to the buffer. Buffer 420 is of conventional construction, typical examples of which are Model 4076 and Model 74C173. The outputs of this buffer are coupled in common to data inputs of RAM 424 and also to respective inputs of address latch circuit 426. One embodiment of the address latch circuit is a Model LS197 latching circuit. The address latch circuit is adapted to receive and store a word supplied thereto via bus 422 from buffer 420. The manner in which address latch circuit 426 is operated to store only address words will be described in greater detail below with respect to FIG. 7. 
     The outputs from address latch circuit 426 corresponding to the bits of an address word are coupled to the A inputs of address multiplexer 428. The address latch circuit additionally includes a further output which is provided with a control bit when the address word stored in address latch circuit 426 precedes a predetermined number of position data words. This control bit is supplied via a lead 436 to counting circuit 432. 
     Address multiplexer 428 is a conventional multiplexing circuit, one embodiment of which is a Model LS157 multiplexer. This address multiplexer includes a set of B inputs which are connected to receive address signals generated from an address generator constituted by timing counter 438. Address multiplexer 428 also includes a selector input 444 coupled to a control circuit 442 to receive an input control signal. This input control signal, referred to as the MEMRD signal is a pulse signal adapted to select inputs A when, for example, this signal is at its relatively lower level, and to select inputs B when at its relatively higher level. As will be explained below with respect to the timing diagrams shown in FIGS. 6A-6E, address multiplexer 428 normally is conditioned such that its A inputs are selected, and this condition is interrupted periodically and briefly to select its B inputs. It is appreciated that the data applied to the selected inputs of the address multiplexer are transmitted therethrough to its outputs. These outputs are coupled to address selection inputs, referred to merely as the address inputs, of RAM 424. Data is written into locations or read out of locations of the RAM in accordance with the address supplied to its address inputs by address multiplexer 428. The data which is written into the RAM is constituted by the particular data word that is supplied to the data inputs from buffer 420 via bus 422. The words which are read out of RAm 424, that is, the position data words or the indicator data words, are supplied from the data ouputs thereof to selected ones of the indicators and numerical display elements, referred to collectively as displays 446. The manner in which a paraticular indicator or numerical display element is energized will be described in detail with respect to FIG. 5. 
     Counting circuit 432 is adapted to produce an &#34;enable&#34; signal in response to the &#34;ready&#34; signal applied thereto from serial-to-parallel converter 308 and in response to a timing signal supplied thereto via lead 440 from timing counter 438. As will be described below with respect to FIG. 7, the &#34;enable&#34; signal is a negative-going pulse signal which enables address latch circuit 426 to &#34;latch&#34; or store the word then supplied thereto from buffer 420. This stored word is modified only when the &#34;enable&#34; signal is produced. The operation of counting circuit 432 is modified in the presence of the control bit supplied thereto via lead 436 from address latch circuit 426 so as to modify the generation of the &#34;enable&#34; signal. For example, in the format wherein the CPU transmits an address word, followed by an indicator word, followed by an address word, and so on, the &#34;enable&#34; signal is produced at every other word, in coincidence with each received address word. However, when the CPU transmits an address word, followed by a predetermined number (for example, four) of position data words, the address latch circuit is enabled only in coincidence with the received address word and not at every alternate word. Thus, position data words are not erroneously stored in address latch circuit 26. Similarly, when position data is received from the VTR&#39;s, such position data is constituted by four position data words preceded by a single pre-set address word, the latter being generated by pre-set address generator 408. In this mode, the &#34;enable&#34; signal is generated in coincidence with the single address word and is inhibited for the duration that the data words are received. 
     The output of this counting circuit 432 is coupled, via lead 433, to a memory write generator 434. This memory write generator, described in greater detail below with respect to FIG. 7, is adapted to produce a MEMWR signal that is supplied to RAM 424 via lead 435. The condition of this MEMWR signal determines whether data is written into the RAM or read out therefrom at the address supplied by address multiplexer 428. This MEMWR signal is synchronized with the respective indicator and position data words such that only these words are written into the RAM. At all other times, RAM 424 is conditioned to read out the data words which are stored at the locations then addressed by address multiplexer 428. A more detailed explanation of the memory write generator and the MEMWR signal are described below with reference to FIG. 7. 
     Timing counter 438 may be a conventional timing device supplied with a relatively higher frequency oscillating signal and adapted to divide the frequency of that signal for use as read-out addresses. One embodiment of this timing counter is a Model LS197. Typically, timing counter 438 includes twelve outputs for providing frequency-divided timing signals having divided frequencies ranging from 2 0  -2 12  of the input oscillating signal. These outputs of timing counter 438 are designated outputs 0, 2, 4, 16, 32, 64, 128, 256, 512, 1024 and 2048, respectively. Outputs 2, 4, 128, 256, 512 and 1024 are coupled to respective ones of the B inputs of address multiplexer 428. As the binary signals provided at these respective outputs of the timing counter vary, the address defined thereby likewise varies. 
     Outputs 8 and 64 of timing counter 438 also are coupled to control circuit 442. This control circuit is comprised of an inverter 443, a clocked flip-flop circuit 445, and a NAND gate 447. In particular, the &#34;64&#34; output is coupled to the clock input CK of flip-flop circuit 445 via inverter 443. The clocked flip-flop circuit also includes a D input, supplied with a constant positive potential, and a reset input R, the latter being coupled to the output of NAND gate 447. One input of this NAND gate is connected to the Q output of flip-flop circuit 445, and the other input thereto is coupled to the &#34;8&#34; output of timing counter 438. The Q output of flip-flop circuit 445 also is supplied as the input selector signal MEMRD to selector input 444 of address multiplexer 428. The manner in which control circuit 442 operates will be described below. 
     As shown in FIG. 4A, the inputs to buffer 416 also are coupled to the outputs of a gating circuit 415, this gating circuit being described in greater detail with respect to FIG. 10. Gating circuit 415 is adapted to receive the position data derived from the VTR&#39;s. In addition, a gate signal is supplied to this gating circuit, as will be described, to enable the position data derived from the VTR&#39;s to be transmitted through buffer 416 and thence to RAM 424. 
     The manner in which the apparatus illustrated in FIGS. 4A and 4B operates to receive data from the CPU and to store that data at appropriate addresses in RAM 424 now will be described. 
     Let it be assumed that the CPU is in condition to transmit data to RAM 424. A suitable signal is supplied to the set input S of flip-flop circuit 402, thereby conditioning AND gate 404. If the contents of buffer 416 are &#34;empty&#34;, that is, if a data word is not stored within this buffer, then a binary &#34;1&#34; is supplied via lead 418 to the other input of AND gate 404, thereby energizing this AND gate to produce an enabling signal to apprise the CPU that data transmission may begin. 
     Let it be assumed that the CPU transmits indicator control signals which, in the present embodiment, are constituted by a single indicator data word preceded by a single address word, this address word identifying the particular address in RAM 424 in which the indicator word is to be stored. This address word also serves to identify the particular indicators of console 10 which are to be energized in accordance with the indicator control signals represented by the indicator data word. Thus, the CPU transmits an address word followed by an indicator data word to bi-directional buffer 328 via system data bus 332. It is appreciated that, when the CPU transmits data to the bi-directional buffer, the transmit/receive control signal applied to lead 330 conditions the bi-directional buffer to receive data from the system data bus. This received data is transferred to internal data bus 314 and supplied to the B inputs of multiplexer 406. 
     When the CPU is conditioned to transmit data, and during such data transmissions, the multiplex control signal supplied via lead 410 to the selector input of multiplexer 406 results in the selection of the B inputs. Thus, in the example being described, the successive words supplied to bi-directional buffer 328 from the CPU are transmitted through the multiplexer to buffer 416. 
     In its programmed routine to transmit data to RAM 424, the CPU also supplies an enable signal to buffer 416 via lead 412. The buffer thus is conditioned to transfer the words supplied thereto from multiplexer 406 to parallel-to-serial converter 312 in synchronism with the clock signals which are applied to this buffer via lead 414. Converter 312 serializes each word supplied thereto from buffer 416, and each serialized word is supplied to serial-to-parallel converter 308. When a complete word has been received by converter 308, the &#34;ready&#34; signal is produced thereby and supplied by lead 430 to counting circuit 432. This &#34;ready&#34; signal cooperates with the timing signal derived from the &#34;2&#34; output of timing counter 438 to supply the &#34;enable&#34; signal to address latch circuit 426. Hence, when the first complete word transmitted from the CPU is received by serial-to-parallel converter 308, address latch circuit 426 is enabled to store this word therein. It is recalled that this first word is an address word, and it is supplied to the address latch circuit via buffer 420. This address word also is supplied to the data inputs of RAM 424 but, as will be appreciated, has no effect upon the contents of the RAM because, at this time, the MEMWR signal is not produced. 
     At this time, let it be assumed that the MEMRD selector signal supplied to selector input 444 of address multiplexer 428 actuates this multiplexer to select its A inputs. Hence, the address word stored in address latch circuit 426 is supplied to the address inputs of RAM 424 via address multiplexer 428. Consequently, the particular location in the RAM which now is addressed by the stored address word is conditioned to have a data word written therein. Of course, the actual writing in of data into the address location does not occur until the MEMWR signal is produced by memory write generator 434. 
     Following the transmission of the address word by the CPU, the data word then is transmitted. In accordance with the present example, it is assumed that this data word is constituted by a single indicator data word. When the complete indicator data word is received by serial-to-parallel converter 308, the &#34;ready&#34; signal is supplied to counting circuit 432. It is recalled that, in response to the first &#34;ready&#34; signal, the counting circuit generated the &#34;enable&#34; signal to enable address latch circuit 426 to receive and store the preceding address word. As will be described below, this &#34;enable&#34; signal is of a predetermined, brief duration. The next &#34;ready&#34; signal produced by serial-to-parallel converter 308 is counted by counting circuit 432 whose count now triggers memory write generator 434 to produce the MEMWR signal. It will be appreciated, therefore, that the MEMWR signal is supplied to RAM 424 in time synchronism with the &#34;ready&#34; signal produced by converter 308. That is, when a complete indicator data word has been received by this converter, RAM 424 is enabled to carry out its write-in operation. The indicator data word is supplied to the data inputs of RAM 424 by buffer 420 and, in response to the MEMWR signal, this indicator data word is written into the location then being addressed by address latch circuit 426. 
     When multiplexer 406 supplies a word to buffer 416, for example, the address word transmitted from the CPU, buffer 416 applies a binary &#34;0&#34; to lead 418, thus indicating that data now is being processed by this buffer, thereby disabling AND gate 404. Consequently, while buffer 416 is processing data, the CPU is advised to delay the initiation of another data transmission operation. The capacity of buffer 416 is sufficient such that a satisfactory number of data words may be &#34;clocked&#34; therethrough in succession. 
     Let it now be assumed that, in place of the single indicator word, the CPU transmits a predetermined number, (for example, 4) of position data words. It is recalled that time code address data is an 8-digit decimal number consisting of a 2-digit number representing hours, a 2-digit number representing minutes, a 2-digit number representing seconds and 2-digit number representing frames. As is known, a decimal digit can be represented by a 4-bit character. Thus, each 2-digit number (i.e. hours, minutes, seconds and frames) may be represented by an 8-bit word, the first four bits representing one digit and the second four bits representing the other digit. Thus, a complete time code address is represented by four position data words. 
     As mentioned above, and in accordance with the example being described, the CPU transmits this position data as four sequential position data words, this block of four position data words being preceded by a single address word. The address word, of course, identifies the particular display register in which the data, represented by the following four sequential position data words, should be displayed. More particularly, the address word identifies the first location in RAM 424 in which these four successive position data words are to be stored. 
     As before, the first word transmitted from the CPU, that is, the address word, is transferred through bi-directional buffer 328, multiplexer 406, buffer 416, parallel-to-serial converter 312 and serial-to-parallel converter 308. When a complete address word has been received by the latter converter, the &#34;ready&#34; signal is produced and is counted by counting circuit 432. In response to this first &#34;ready&#34; signal, the counting circuit produces the &#34;enable&#34; signal to enable address latch circuit 426 to receive and store the address word then supplied thereto via buffer 420 from serial-to-parallel converter 308. The address now stored in address latch circuit 426 is supplied through address multiplexer 428 to the address input of RAM 424, thereby defining the particular location in which the next-following data is to be stored. At this time, however, the MEMWR signal is not yet produced. 
     The next-following word received from the CPU is the first position data word. This position data word is supplied via bi-directional buffer 328, multiplexer 406, buffer 416, and parallel-to-serial converter 312 to serial-to-parallel converter 308. Upon receipt of the complete position data word, another &#34;ready&#34; signal is produced and is counted by counting circuit 432. At this time, however, the address word stored in address latch circuit 426 contains the control bit which, it is recalled, is provided by the CPU when the address word precedes the predetermined number (e.g. 4) of position data words. This control bit is supplied to counting circuit 432 to condition the counting circuit to count each of the &#34;ready&#34; signals produced by the four successive position data words following the received address word. Each of these &#34;ready&#34; signals supplied to the counting circuit results in the triggering of memory write generator 434 so as to produce four successive MEMWR signals. Each of these MEMWR signals enables RAM 424 to write the position data word then supplied to its data inputs into the address supplied to its address inputs. It is recognized that, in response to the control bit supplied from address latch circuit 426 to counting circuit 432, the counting circuit is inhibited from producing the &#34;enable&#34; signal until after all four of these position data words have been written into the RAM. Thus, none of the successive position data words that are received by serial-to-parallel converter 308 can be stored in the address latch circuit. 
     It is appreciated that each position data word should be stored in a separately addressed location in RAM 424. The address word stored in address latch circuit 426 identifies the first such memory location. Then, although this address word is not changed by any of the successive position data words which are received by converter 308, each MEMWR signal is supplied as a clock clock signal to the address latch circuit, thereby incrementing the address stored therein by a respective one count. More particularly, the stored address is incremented in response to each trailing edge of the MEMWR signal. Hence, the first position data word that is transmitted by the CPU immediately following the address word is stored in the address location identified by the specific address word that preceded it, which preceding address word is stored in address latch circuit 426. After this position data word is written into the RAM, the address stored in address latch circuit 426 is incremented by one count in response to the trailing edge of the MEMWR signal, thereby defining the next sequential address into which the next-following position data word is written. This process continues until four such position data words have been written into four sequential addresses in RAM 424. In response to the fourth position data word, the &#34;ready&#34; signal supplied to counting circuit 432 returns this counting circuit to its initial condition, thereby awaiting receipt of the next word, presumed to be an address word, so as to produce the &#34;enable&#34; signal. 
     Thus, it is seen that when indicator data is transmitted from the CPU, the indicator data word is preceded by an address word, and counting circuit 432 generates the &#34;enable&#34; signal to store this preceding address word in address latch circuit 426. Then, in response to the following indicator data word, counting circuit 432 triggers memory write generator 434 to generate the MEMWR signal such that the indicator data word is written into the addressed location in RAM 424. Although the trailing edge of this MEMWR signal increments the address stored in address latch circut 426, this has no effect on the memory write-in operation, because it is assumed that the next-following word is an address word which, of course, is stored in address latch circuit 426 regardless of the previously incremented address which may be stored therein. 
     When position data is transmitted from the CPU, counting circuit 432 is responsive to the first word, which is the address word, to supply address latch circuit 426 with the &#34;enable&#34; signal. Hence, this address word is stored in the address latch circuit so as to define the location in which the next-following position data words are to be stored. The first of these position data words is supplied to the data inputs of RAM 424 and, in response to the &#34;ready&#34; signal produced when the complete position data word is received by serial-to-parallel converter 308, counting circuit 432 triggers memory write generator 434 to generate the MEMWR signal so as to enable the position data word to be written into the address location. At the trailing edge of this MEMWR signal, the address stored in address latch circuit 426 is incremented by one count. Of course, the control bit remains stored in address latch circuit 426 so as to prevent counting circuit 432 from being reset to its initial condition in response to this position data word. That is, the counting circuit does not respond to the next word as if that word is an address word. Rather, this next position data word results in the generation of another MEMWR signal such that it is written into the location then addressed by the incremented address stored in address latch circuit 426. This procedure is repeated until four such position data words have been detected, whereupon counting circuit 432 is reset to its initial condition to await the arrival of the next sequence of data, which sequence is prefaced by an address word. 
     In this manner, address words and position data words are distinguished. In the embodiment shown in FIGS. 4A and 4B, the control bit is stored in address latch circuit 426 (or in any other equivalent storage device) so as to control counting circuit 432 to distinguish between an address word followed by one data word and an address word followed by a plurality of data words. 
     If desired, indicator signals may be transmitted as a first predetermined number of data words, for example, two or three data words, and position data may be transmitted as another predetermined number of data words, such as four, five or six data words. Counting circuit 432 then may be modified so as to distinguish between the number of indicator data words which follow an address word and the number of position data words which follow an address word, for proper control of RAM 424. 
     At times that data words are not written into RAM 424, data words stored therein are read out. Although not shown in FIG. 4B, it should be appreciated that suitable read/write control circuitry is provided (such as shown in FIGS. 14A-14C) to prevent a read operation from being initiated while a write operation is being carried out. The addresses from which the data stored in RAM 424 are read are generated by timing counter 438. Furthermore, this timing counter cooperates with control circuit 442 to control address multiplexer 428 whereby, during read-out operations, the B inputs of this address multiplexer are selected. As shown, these B inputs are coupled to a predetermined output of timing counter 438 for receiving the read-out addresses therefrom. Specifically, the read-out addresses are generated by the pulse signals produced at the &#34;2&#34;, &#34;4&#34;, &#34;128&#34;, &#34;256&#34;, &#34;512&#34; and &#34;1024&#34; outputs of the timing counter. 
     The manner in which the MEMERD input selector signal is generated by control circuit 442 to select either the A or B inputs of address multiplexer 428 now will be described with reference to the timing diagrams shown in FIGS. 6A-6E. FIG. 6A represents the timing signal produced by the &#34;8&#34; output of timing counter 438. FIGS. 6B, 6C and 6D represent the timing signals which are produced by the &#34;16&#34;, &#34;32&#34; and &#34;64&#34; outputs of the timing counter, respectively. It is assumed that flip-flop circuit 445 is a clocked flip-flop circuit such that that Q output thereof is provided with a signal corresponding to the signal supplied to its D input at the negative edge of the clock signal supplied to its clock CK input. It is further assumed that if a relatively low level, such as a binary &#34;0&#34;, is supplied to its reset input R, flip-flop circuit 445 remains in its reset state, whereby the Q output produces a binary &#34;0&#34;. 
     In accordance with this understanding, inverter 443 inverts the timing signal produced at the &#34;64&#34; output of timing counter 438, such that flip-flop circuit 445 is set to produce a binary &#34;1&#34; at the Q output thereof at the positive edge of the timing signal shown in FIG. 6D. When flip-flop circuit 445 is set, NAND gate 447 is supplied with a binary &#34;1&#34; at one input thereof. At the next-following positive transition in the timing signal produced at the &#34;8&#34; output of timing counter 438 shown in FIG. 6A, NAND gate 447 is supplied with a binary &#34;1&#34; at each input thereof so as to supply a binary &#34;0&#34;  to the reset input R of flip-flop circuit 445. The resultant signal produced at the Q output of this flip-flop circuit, which is the MEMRD signal, is as shown in FIG. 6E. 
     Thus, it is seen that address multiplexer 428 is controlled, periodically, to select its B inputs in response to the MEMRD pulses shown in FIG. 6E. During the duration of each MEMRD pulse, four successive addresses are generated by timing counter 438. Furthermore, the duration of a memory read-out operation is substantially coincident with the duration of each of these MEMRD pulses. As a numerical example, the MEMRD pulses are generated at a frequency of 38.4 KHz, and the address supplied to the B inputs of address multiplexer 428 by timing counter 438 changes at the rate of 1.23 MHz. 
     In the interval between successive MEMRD pulses, a write-in operation is enabled to be carried out, and the MEMWR signal is produced during this interval. 
     During the read-out operation wherein the address supplied to RAM 424 is from the B inputs of address multiplexer 428, the data stored in each address location is read out and supplied to displays 446. As mentioned above, the manner in which the data read out from the RAM is used to energize these displays is discussed with reference to FIG. 5. 
     Reference now is made briefly to the use of pre-set address generator 408 and gating circuit 415. Position data derived from the VTR&#39;s is supplied to gating circuit 415. When the CPU is not transmitting data to RAM 424, and when the contents of buffer 416 are &#34;empty&#34;, the multiplex control signal supplied to multiplexer 406 selects the A inputs thereof. If position data derived from the VTR&#39;s is available to be transmitted to the RAM, pre-set address generator 408 is actuated to establish the address within RAM 424 in which position data derived from the playback tape or position data derived from the recording tape is to be stored. This address is supplied from pre-set address generator 408, through the A inputs of multiplexer 406, buffer 416, parallel-to-serial converter 312 and serial-to-parallel converter 308. The remaining apparatus shown in FIG. 4B operates in response to this address word in the manner discussed hereinabove. Hence, this address word is stored in address latch circuit 426. Since this address word represents the address in which position data is stored, and since, it is recalled, position data is constituted by four successive position data words successively following the address word, the address word stored in the address latch circuit contains the aforementioned control bit, whereby counting circuit 432 is controlled in the manner discussed above. 
     After the pre-set address is supplied from inputs A of multiplexer 406 to buffer 416, the multiplexer is disabled and gating circuit 415 now is enabled to gate the position data supplied thereto from the VTR&#39;s to buffer 416. These successive position data words are transferred to serial-to-parallel converter 308, and counting circuit 432 responds to each &#34;ready&#34; signal produced by this converter as each complete data word is received to trigger memory write generator 434 to write in each of these position data words into the addresses then produced by address latch circuit 426. As was discussed above, the specific address first stored in the address latch circuit, that is, the pre-set address supplied thereto from pre-set address generator 408 by multiplexer 406, is incremented by a count of one as each position data word is written into RAM 424. Hence, the position data words that are derived from the VTR&#39;s are written into successive memory locations in RAM 424. 
     As will be described further below with respect to FIG. 10, after the position data derived from one VTR is written into predetermined locations in RAM 424, the position data derived from the other VTR is written into its respective address location. This second operation of writing in the position data is substantially the same as the first-described operation and, in order to avoid unnecessary duplication of description, further explanation thereof is not provided. Suffice it to say that, when the CPU is not transmitting data to RAM 424, and when the contents of buffer 416 are &#34;empty&#34;, a pre-set address word is supplied from the A inputs of multiplexer 406 to address latch circuit 426 to determine the locations in RAM 424 in which the next-following four successive position data words are stored. These position data words are, of course, derived from one of the VTR&#39;s. After such position data words have been stored in RAM 424, this operation is repeated in order to store the four position data words derived from the other VTR. 
     From the foregoing description, it should be fully appreciated that RAM 424 stores position data words and indicator data words at predetermined address locations therein. The manner in which such data words are used to energize the respective indicators and displays of console 10 (FIG. 1) now will be described. 
     Memory Read-Out for Display Control 
     As mentioned above, position data words and indicator data words are stored in RAM 424 in locations corresponding to the particular numerical display elements and indicator elements which are to be energized by such words. Each word is comprised of eight bits and, since each numerical display element is energized by four bits, it is recognized that each position data word serves to energize two numerical display elements. Consequently, when a position data word is read out of an address location from RAM 424, this word serves to energize two predetermined numerical display elements. 
     With respect to the indicator elements, such as the indicator lamps associated with respective ones of the display switches of console 10, each indicator lamp is adapted to be energized, or turned ON, to be turned OFF and to be flashed. To achieve this, four bits of each 8-bit indicator data word are adapted to energize four corresponding indicator elements to be either ON or OFF, and the other four bits of that indicator data word are adapted to determine whether these four indicator lamps are flashed. For example, of the first-mentioned four bits, a binary &#34;1&#34; is effective to turn the indicator lamp ON and a binary &#34;0&#34; is effective to turn it OFF. Of the second-mentioned four bits, a binary &#34;1&#34; is effective to flash the indicator lamp (providing it has been turned ON), and a binary &#34;0&#34; represents that the indicator lamp is not to be flashed. 
     In a preferred embodiment, RAM 424 may be considered to be divided into four separate sections, the first three sections storing position data words and the fourth section storing indicator data words. During a read-out operation, a particular location is addressed successively in each of these sections, followed by the next location, and so on. For example, location 1 is addressed in section 1, followed by location 1 in section 2, followed by location 1 in section 3, followed by location 1 in section 4. Then, location 2 in section 1 is addressed, followed by location 2 in section 2, followed by location 2 in section 3, followed by location 2 in section 4. This read-out addressing technique continues until all of the locations in all of the sections have been addressed and read out. Thus, and with reference to the MEMRD signal shown in FIG. 6E, during each pulse duration, a particular location is read out from each of the sections in RAM 424. Then, during the next pulse duration, the next sequential location is read out from each of these sections. Timing counter 438 serves to generate the appropriate address, wherein outputs &#34;2&#34; and &#34;4&#34; of the timing counter determine the particular section which is to be addressed, and outputs &#34;128&#34;, &#34;256&#34;, &#34;512&#34; and &#34;1024&#34; determine the particular location that is to be addressed in each section. 
     The apparatus which is used to energize the particular numerical display elements or indicator lamps associated with the position data word or indicator data word which is read from an addressed location in RAM 424 is illustrated in FIG. 5. This apparatus is comprised of decoders 502 and 504, drivers 542, latch circuits 506, . . . 520, 7-segment drivers 522 . . . 532, OR gates 550 . . . 556, AND gates 560 . . . 566, lamp drivers 568 . . . 574 and blinking oscillator 558. FIG. 5 also illustrates that each of the numerical display elements is a 7-segment display of the type mentioned hereinabove, these 7-segment displays being disposed in array 540. Similarly, FIG. 5 illustrates that the indicator lamps are disposed in array 580. 
     In the illustrated embodiment, the 7-segment display elements 540 are arranged in three separate groups, each group being defined by the address signals produced at outputs &#34;2&#34; and &#34;4&#34; of timing counter 438. If these groups are identified as groups 0, 1 and 2, then group 0 is identified by the combination 00 produced at outputs &#34;4&#34; and &#34;2&#34;, respectively, group 1 is identified by the combination 01, and group 2 is identified by the combination 10. When this combination of signals at outputs &#34;4&#34; and &#34;2&#34; corresponds to 11, indicator lamps 580 are identified. Decoder 502, one embodiment of which may be a Model LS139, is connected to receive the signals provided at outputs &#34;4&#34; and &#34;2&#34;, respectively, and to decode these outputs so as to produce a respective group selection signal as a function of the combination of these received signals. Thus, group selection signal GR0 is produced in response to the combination 00, group selection signal GR1 is produced in response to the combination 01, group selection signal GR2 is produced in response to the combination 10 and group direction signal GR3 is produced in response to the combination 11. Group selection signal GR0 is supplied to latch circuits 506 and 508 and is adapted, when produced, to enable these latch circuits to store the digital signals then supplied thereto. As shown, latch circuits 506 and 508 are connected to the outputs 448 of RAM 424 and are adapted to receive the data word read out from an address location in the RAM. Four bits of the read-out word are supplied to latch circuit 506 and the other four bits of this word are supplied to latch circuit 508. Thus, each latch circuit is supplied with a 4-bit signal representative of a decimal digit. 
     In a similar manner, group selection signal GR1 is supplied to latch circuits 510 and 512, the inputs of these latch circuits being connected in common with latch circuits 506 and 508 to outputs 448 of RAM 424. Group selection signal GR2 is supplied to latch circuits 514 and 516, the inputs of these latch circuits being connected in common with the aforementioned latch circuits. Group selection signal GR3 is supplied to latch circuits 518 and 520, the inputs of these latch circuits also being connected in common with the aforementioned latch circuits. 
     The outputs of latch circuits 506 and 508 are connected to 7-segment drivers 522 and 524, respectively. These 7-segment drivers are conventional and are adapted to energize the respective display members in each 7-segment element as a function of the 4-bit signal that is supplied to and stored in latch circuits 506 and 508. In this regard, each latch circuit may also include decoding circuitry or, if desired, each 7-segment driver may include such decoding circuitry. Similarly, the outputs of latch circuits 510 and 512 are connected to 7-segment drivers 526 and 528, and the outputs of latch circuits 514 and 516 are connected to 7-segment drivers 530 and 532. 
     In the illustrated embodiment, each 7-segment driver is connected in common with sixteen separate 7-segment elements. Thus, the four bits stored in, for example, latch circuit 506 are adapted to energize sixteen separate 7-segment display elements. Similarly, the four bits stored in latch circuit 508 are adapted to energize sixteen different ones of the 7-segment display elements. However, each display element also is connected to an actuating lead, identified as leads D0, D1, D2 . . . D15, only one of which is supplied with an actuating signal at any given time. The particular 7-segment display element which is energized thus is limited to that particular element which is driven by a respective 7-segment driver and, also, is supplied with an actuating signal that is present on one of these leads. 
     Leads D0 . . . D15 are connected to respective outputs of drivers 542, which drivers are supplied with decoded signals produced by decoder 504 in response to the signals supplied to the decoder from outputs &#34;128&#34;, &#34;256&#34;, &#34;512&#34; and &#34;1024&#34; of timing counter 438. It is appreciated that sixteen separate combinations are available from the 4-bit signal supplied to the decoder from the timing counter. Thus, depending upon the condition of this 4-bit signal, a corresponding one lead D0 . . . D15 is supplied with an actuating signal. 
     Before describing the apparatus which is connected to indicator lamps 580, the manner in which 7-segment display elements 540 are energized now will be briefly described. As the read-out address generated by timing counter 438 changes, the particular 7-segment display that is energized changes in a corresponding manner. For example, let it be assumed that timing counter 438 addresses a location in RAM 424 in which is stored the position data word corresponding to the &#34;frames&#34;  digits of a particular display register. Let it be further assumed that the 7-segment display elements which are to display these &#34;frames&#34; digits are elements 540a and 540b. This address is, of course, represented by the address bits provided at outputs &#34;2&#34;, &#34;4&#34;, &#34;128&#34;, &#34;256&#34;, &#34;512&#34; and &#34;1024&#34; of timer counter 438. Outputs &#34;2&#34; and &#34;4&#34; are decoded to produce group selection signal GR0, thus enabling latch circuits 506 and 508 to store the position data word read from RAM 424. Seven-segment drivers 522 and 524 thus are conditioned to energize all of the 7-segment display elements connected thereto, including elements 540a and 540b. 
     The remaining bits in the address generated by timing counter 438 are decoded by decoder 504 to supply the actuating signal to lead D0. This actuating signal thus is applied to all of the 7-segment display elements that are connected to lead D0, including elements 540a and 540b. Since these latter elements are the only elements that are connected to lead D0 and also are supplied with energizing signals, elements 540a and 540b are energized to display the &#34;frames&#34; digits. 
     The address supplied to RAM 424 by timing counter 438 next is changed by a change in the bits produced at outputs &#34;2&#34; and &#34;4&#34;. The remaining address bits remain the same. This change in the address bits produces group selection signal GR1. Consequently, the position data word now read out of RAM 424 is stored only in latch circuits 510 and 512. Seven-segment drivers 526 and 528 are supplied with energizing signals, and only those 7-segment display elements which are driven by 7-segment counters 526 and 528 and which also are connected to lead D0 are energized. 
     The foregoing operation is repeated as each address word supplied to RAM 424 by timing counter 438 changes. From FIG. 6E, it is seen that after all four group selection signals GR0, GR1, GR2 and GR3 have been produced, in sequence, the read-out operation terminates. When the read-out operation next is instituted, the address bits supplied from timing counter 438 to decoder 504 will be changed, such that the actuating signal now is supplied to, for example, lead D1. Then, those 7-segment display elements which are connected to lead D1 and which also receive energizing signals from their respective 7-segment drivers will be energized in response to the position data words read out from RAM 424. 
     It is appreciated, therefore, that the 7-segment drivers and actuating leads D0 . . . D15 are arranged in a matrix configuration, wherein the 7-segment drivers may be considered as columns and the actuating leads may be considered as rows. Those 7-segment elements which are defined by a particular column and row are energized, or actuated, and will display the numerical data represented by the position data word then read from RAM 424. 
     As a numerical example, the rate at which the bit produced at output &#34;1024&#34; of timing counter 438 changes may be equal to 1.2 KHz. This is the frequency at which each 7-segment display element is energized. That is, all of the 7-segment display elements provided in the respective display registers of console 10 are energized sequentially and cyclically. This 1.2 KHz rate is sufficiently high that the operator does not perceive any visible blinking in these elements. Thus, to his eye, all of the display elements are energized concurrently. 
     Turning now to the apparatus for energizing indicator lamps 580, it may be appreciated that these indicator lamps are energized in a similar manner as that discussed above with respect to the 7-segment display elements. Indicator lamps 580 are arranged in groups of four lamps in each group. Each group is connected to an actuating lead, referred to as a lamp actuating lead, L0, L1 . . . L15, and each of these lamp actuating leads is connected in common with a respective one of the aforementioned display element actuating leads D0 . . . D15. Thus, when a particular display element actuating lead is supplied with an actuating signal, its corresponding lamp actuating lead also is supplied with that actuating signal. 
     A particular lamp in each of the sixteen groups of lamps is connected to a respective one of lamp drivers 568, 570, 572 and 574. Thus, when one of these drivers is energized, all of the lamps (i.e. sixteen indicator lamps) connected thereto are conditioned to be energized. However, the only one of these sixteen lamps which actually is energized is the one which also is connected to the lamp actuating lead to which an actuating signal is supplied. 
     The particular lamp driver that is energized is determined by the bits constituting the indicator word that is read from RAM 424 and stored in latch circuits 518 and 520. The four bits stored in latch circuit 520 determine the ON and OFF condition of lamp drivers 568, 570, 572 and 574; and the four bits stored in latch circuit 518 determine the flashing condition of these lamp drivers. To this effect, OR gates 550, 552, 554 and 556 are connected to respective outputs of latch circuit 518. These OR gates also receive a slowly oscillating signal, corresponding to the flash rate for indicator lamps 580, from oscillator 558. The outputs of OR gates 550, 552, 554 and 556 are connected to one input of AND gates 560, 562, 564 and 566, respectively. The other inputs of these latter AND gates are connected to latch circuit 520 to receive the ON and OFF bits stored therein. The outputs of AND gates 560, 562, 564 and 566 are connected to lamp drivers 568, 570, 572 and 574, respectively. 
     In operation, when the read-out address produced by timing counter 438 identifies a location in which an indicator data word is stored, this same address will produce group selection signal GR 3. Thus, only latch circuits 518 and 520 will be enabled to receive the indicator data word then read from the RAM. Depending upon the ON and OFF bits, as well as the flash-control bits which constitute this indicator data word, respective ones of drivers 568, 570, 572 and 574 will be energized, and such energized drivers will be either in the steady energization state or the flashing energization state. Suitable energizing signals are supplied by these lamp drivers to all of the indicator lamps connected thereto. However, the address which identifies the particular location in RAM 424 from which the indicator data word has been read also selects a single one of lamp actuating leads L0 . . . L15 to which an actuating signal is supplied. Thus, only those indicator lamps which are connected to this lead will be energized by lamp drivers 568 . . . 574. In this manner, as each indicator data word is read from the RAM, four indicator lamps that are associated with the memory location which has been addressed will be selectively energized by the read-out indicator data word. 
     From the foregoing, it is seen that, as the contents of RAM 424 are read out sequentially, three pairs of 7-segment display elements 540, followed by four indicator lamps 580 are actuated successively in accordance with the read out position and indicator data words. The rate at which such data words are read from the RAM, and thus, the rate at which these display and indicator elements are energized, is sufficiently high such that the operator does not perceive any so-called blinking on console 10. Of course, those indicator lamps which are to be flashed will be flashed at a clearly perceptable rate, such as on the order of 1 or 2 Hz. Hence, the data stored in RAM 424 is displayed on console 10. Of course, as new data is supplied to the RAM, such as updated position data derived from the VTR&#39;s, or data that is supplied thereto from the CPU, as discussed above with respect to FIGS. 4A and 4B, this new data also is displayed. 
     Address and Write Control Circuit 
     Referring to FIG. 7, there is illustrated a logic circuit diagram of one embodiment of counting circuit 432 and memory write generator 434 (shown in FIG. 4B). It is recalled that counting circuit 432 functions to generate the &#34;enable&#34; signal, whereby address latch circuit 426 is enabled to store an address word then supplied thereto. The contents of the address latch circuit remain therein in the absence of such an &#34;enable&#34; signal. Memory write generator 434 serves to produce the MEMWR signal for enabling a data word to be written into an address location of RAM 424. A memory write operation is not performed unless the MEMWR signal is produced. 
     Counting circuit 432 is comprised of clocked flip-flop circuits 702 and 704 and NAND gate 708. Memory write generator 434 is comprised of clocked flip-flop circuits 716 and 718, and NAND gates 712, 714 and 720. For convenience, the circuitry shown in FIG. 7 is described in its entirety, and not as separate counting and memory write generating circuits. Each of the clocked flip-flop circuits illustrated in FIG. 7 is a D-type flip-flop device having a data input D, a clock input CK, and Q and Q outputs. Such flip-flop circuits also include a reset input R which, when supplied with a relatively low level signal, such as a binary &#34;0&#34;, serves to reset the flip-flop circuit. The set state of the clocked flip-flop circuit is represented by a binary &#34;1&#34; at its Q output and a binary &#34;0&#34; at its Q output. These signals are reversed when the flip-flop circuit is reset. 
     The D input of flip-flop circuit 702 is coupled to serial-to-parallel converter 308 via lead 430, as described above with respect to FIG. 4B. Hence, this D input is adapted to receive the &#34;ready&#34; signal when the serial-to-parallel converter is supplied with a complete word. The clock input CK of flip-flop circuit 702 is supplied with a clock signal generated from the &#34;2&#34; output of timing counter 438 and supplied thereto via lead 440. In the embodiments described herein, each clocked flip-flop circuit is adapted to be triggered in response to the positive-going, or leading edge of the clock signals supplied to its clock input CK. If desired, each of these flip-flop circuits may be of the so-called negative-edge triggering type. It is appreciated that, when triggered, the flip-flop circuit is set if a binary &#34;1&#34; is supplied to its D input and is reset if a binary &#34;0&#34; is supplied thereto. 
     The Q output of flip-flop circuit 702 is connected in common to a respective input of each of NAND gates 708 and 714. It is appreciated that a NAND gate is adapted to produce a binary &#34;0&#34; only when a binary &#34;1&#34; is supplied to each of its inputs. If a binary &#34;0&#34; is supplied to any input thereof, the NAND gate produces a binary &#34;1&#34;. 
     Flip-flop circuit 704 has its D input connected to its Q output, and its clock input CK connected to the Q output of flip-flop circuit 702. In addition, the Q output of flip-flop circuit 704 is connected to another input of NAND gate 708, and its Q output is connected to another input of NAND gate 714, and also to a respective input of NAND gate 712. The remaining inputs of NAND gates 708 and 714 are connected to receive the clock signal supplied to lead 440 by timing counter 438 after this clock signal has passed through inverter 706. 
     The output of NAND gate 708 is connected to lead 433 to produce the &#34;enable&#34; signal and, additionally, is connected to the reset input R of each of flip-flop circuits 716 and 718. These flip-flop circuits also have their clock inputs CK connected in common to the output of NAND gate 714. The output of this NAND gate also is connected to lead 435 to produce the MEMWR signal. Flip-flop circuits 716 and 718 are interconnected to comprise a counter, whereby the D input of flip-flop circuit 716 is connected to the Q output of flip-flop circuit 718, and the D input of flip-flop circuit 718 is connected to the Q output of flip-flop circuit 716. The Q and Q outputs of flip-flop circuits 718 and 716, respectively, are connected to corresponding inputs of NAND gate 720, the output of which is connected to an input of NAND gate 712. The remaining input of NAND gate 712 is connected to lead 436 to receive the control bit that may be included in the address word stored in address latch circuit 426, as discussed above. 
     An operation of the circuit illustrated in FIG. 7 in the absence of a control bit in the stored address word now will be described. It is recalled that this control bit is not present if the address word stored in address latch circuit 426 precedes an indicator data word. Referring to the timing diagrams shown in FIGS. 8A-8F, the clock signal supplied to the clock inputs CK of flip-flop circuit 702 is illustrated in FIG. 8A. Let it be assumed that a &#34;ready&#34; signal is produced by serial-to-parallel converter 308, as shown in FIG. 8B. It is appreciated that the first &#34;ready&#34; signal represents that a complete address word has been received by this converter, the second &#34;ready&#34; signal represents that a complete indicator word has been received, the third &#34;ready&#34; signal represents that a complete address word has been received and the fourth &#34;ready&#34; signal represents that a complete indicator data word has been received. Thus, as shown in FIG. 8B, it is assumed that the CPU transmits information in the form of an address word followed by a data word followed by an address word, and so on. 
     Flip-flop circuit 702 serves to time-synchronize the &#34;ready&#34; signals which are received from serial-to-parallel converter 308. That is, each of these &#34;ready&#34; signals is synchronized by flip-flop circuit 702 with the leading, or positive-going, edges of the clock signals shown in FIG. 8A. Of course, if flip-flop circuit 702 is a negative-edge triggering type of flip-flop circuit, then the &#34;ready&#34; signals will be synchronized with such negative edges of the clock signal. 
     In the absence of a control bit supplied to lead 436 by address latch circuit 426, a binary &#34;0&#34; is applied via this lead to NAND gate 712. Hence, the NAND gate applies a binary &#34;1&#34; to the reset input R of flip-flop circuit 704. This binary &#34;1&#34; is not effective to reset this flip-flop circuit and enables it to respond to signals supplied to its clock input CK. The signal supplied to the clock input CK of flip-flop circuit 704 is derived from the Q output of flip-flop circuit 702. Flip-flop circuit 704 thus is adapted to change state each time that flip-flop circuit 702 is set, that is, in response to each positive-going transition at the Q output of this flip-flop circuit. FIG. 8D represents that flip-flop circuit 704 is set when the first &#34;ready&#34; signal is produced and is reset when the next-following &#34;ready&#34; signal is produced. Flip-flop circuits 702 and 704 may be thought of as a counting circuit in which the count thereof, as represented by the state of flip-flop circuit 704, is incremented by the first &#34; ready&#34; signal and reset by the next-following &#34;ready&#34; signal. That is, this count is incremented when an address word is received in serial-to-parallel converter 308 and is reset when the next-following data word is received therein. 
     When flip-flop circuits 702 and 704 both exhibit their set states, NAND gate 708 generates the &#34;enable&#34; pulse shown in FIG. 8E in response to the negative half-cycle of the clock signal (FIG. 8A). From a comparison of FIGS. 8A-8F, it is seen that this &#34;enable&#34; signal is produced in response to every other &#34;ready&#34; signal, that is, this &#34;enable&#34; signal is produced when each address word is received but not when the data words are received. Hence, address latch circuit 426 is enabled to store the address word then supplied thereto in response to this &#34;enable&#34; signal. When a data word is supplied to the address latch circuit, the &#34;enable&#34; signal is not produced. Hence, address latch circuit 426 is responsive only to address words and not to data words. 
     As shown in FIG. 8F, NAND gate 714 produces the MEMWR signal in response to the negative half-cycle of the clock signal (FIG. 8A) when flip-flop circuit 702 is in its set state and flip-flop circuit 704 is in its reset state. Since the latter flip-flop circuit is reset in response to the data word which follows the address word, the MEMWR signal is produced when the indicator data word is received thereby enabling RAM 424 to store this indicator data word in the address determined by the contents of address latch circuit 426. 
     The counter arrangement comprised of flip-flop circuits 716 and 718 is actuated in response to each MEMWR pulse produced by NAND gate 714. These flip-flop circuits are represented as having clock inputs CK such that these flip-flop circuits are triggered in response to the positive-going edge of the MEMWR pulse. However, regardless of the count exhibited by this counter arrangement, it is appreciated that each &#34;enable&#34; pulse (FIG. 8A) produced by NAND gate 708 resets the count thereof to an initial count 00. 
     Let it now be assumed that position data words, preceded by an address word, are supplied to serial-to-parallel converter 308. Reference is made to the timing diagrams shown in FIGS. 9A-9K for an understanding of the operation of the circuitry shown in FIG. 7 when position data is received. FIG. 9B represents the &#34;ready&#34; pulses which are produced by converter 308 in response to the address word (&#34;ready&#34; pulse 0) and the four succeeding position data words (&#34;ready&#34; pulses 1, 2, 3 and 4). FIG. 9C is similar to aforedescribed FIG. 8C and illustrates the clock-synchronized &#34;ready&#34; pulses produced by flip-flop circuit 702. FIG. 9D is similar to FIG. 8D and illustrates the state of flip-flop circuit 704, which flip-flop circuit is set in response to &#34;ready&#34; pulse 0 (i.e., the &#34;ready&#34; pulse produced in response to the address word) and is reset in response to &#34;ready&#34; pulse 1 (i.e. the &#34;ready&#34; pulse produced in response to the next-following position data word). FIG. 9E illustrates the &#34;enable&#34; pulse produced by NAND gate 708 in response to the negative half-cycle of the clock signal (FIG. 9A) when flip-flop circuits 702 and 704 both exhibit their set states. 
     It is appreciated that, in response to the &#34;enable&#34; pulse, the address word received by serial-to-parallel converter 308 is shifted into address latch circuit 426. Since this address word is assumed to precede 4 position data words, this address word includes the aforementioned control bit. This control bit is supplied via lead 436 from address latch circuit 426 to NAND gate 712, and is illustrated in FIG. 9K. 
     Let it be assumed that, initially, flip-flop circuits 716 and 718 both exhibit their reset states, such that a binary &#34;0&#34; is supplied from the Q output of flip-flop circuit 718 to NAND gate 720. Hence, NAND gate 720 supplies a binary &#34;1&#34; signal to NAND gate 712, as shown in FIG. 9I. 
     When flip-flop circuit 704 is rest in response to the first position data word (&#34;ready&#34; pulse 1), NAND gate 714 produces a MEMWR signal (FIG. 9F) each time that flip-flop circuit 702 exhibits its set state and the negative half-cycle of the clock signal (FIG. 9A) is present. It is appreciated that when flip-flop circuit 704 exhibits its reset state and NAND gate 720 produces a binary &#34;1&#34;, NAND gate 712 applies a binary &#34;0&#34; to the reset input R of flip-flop circuit 704, thereby maintaining this flip-flop circuit in its reset state regardless of the signals that may be applied to its clock input CK. 
     The positive transition in the MEMWR pulse triggers flip-flop circuit 716 to be set in response to the binary &#34;1&#34; supplied to its D input from the Q output of flip-flop circuit 718. The state of flip-flop circuit 718, as represented by its Q output, is shown in FIG. 9G. Also, the MEMWR pulse is supplied to address latch circuit 426 (as shown in FIG. 4B) to increment the address stored therein by one count after the first position data word has been written into RAM 424. 
     Since flip-flop circuit 704 remains in its reset state, another MEMWR pulse (FIG. 9F) is produced in response to the second position data word (&#34;ready&#34; signal 2). This second MEMWR pulse now triggers flip-flop circuit 718 to its set state, as shown in FIG. 9H, and also increments the address stored in the address latch circuit. 
     Flip-flop circuit 704 remains in its reset state when the third position data word is received (&#34;ready&#34; signal 3), whereby NAND gate 714 produces the third MEMWR pulse, shown in FIG. 9F. The positive transition of this third MEMWR pulse triggers flip-flop circuit 716 to its reset state in response to the binary &#34;0&#34; supplied to its D input from the Q output of flip-flop circuit 718, and also increments the address latch circuit. FIG. 9G illustrates the resetting of flip-flop circuit 716. The signals now supplied to NAND gate 720 from the Q output of flip-flop circuit 716 and from the Q output of flip-flop circuit 718 are equal to [11], whereupon NAND gate 720 supplies the binary &#34;0&#34; shown in FIG. 9I to NAND gate 712. The latter NAND gate now removes the reset binary &#34;0&#34; signal that had been applied to the reset input R of flip-flop circuit 704. 
     In response to the fourth position data word received by serial-to-parallel converter 308 (&#34;ready&#34; signal 4), the fourth MEMWR signal is produced by NAND gate 714 (FIG. 9F) thereby returning flip-flop circuits 716 and 718 to their respective reset [00] states. The circuitry of FIG. 7 thus is in condition to respond to the next address word received by serial-to-parallel converter 308 to produce an &#34;enable&#34; signal followed by one or more MEMWR pulses in response to one or more succeeding data words. It is appreciated that such data words may be constituted by a single indicator data word preceded by an address word or a predetermined number (assumed herein to be four) position data words preceded by a single address word. Such position data words may be transmitted from the CPU or may be derived from the VTR&#39;s as discussed above. In the latter circumstance, such position data words are supplied to serial-to-parallel converter from gating circuit 415 (FIG. 4A). Thus, the circuitry illustrated in FIG. 7 serves to control address latch circuit 426 and RAM 424 to write indicator and position data words into correct addressed locations. 
      Control Circuit for Multiplexer 406 
     It is recalled that multiplexer 406 is controlled by a multiplex control signal applied to lead 410 (FIG. 4A) to select for transmission therethrough the signals applied either to inputs A or inputs B. Normally, inputs B are selected. However, when position data is derived from the VTR&#39;s, then the address word therefor must be transmitted to address latch circuit 426, and this address word is applied to inputs A of multiplexer 406. The circuit illustrated in FIG. 10 is adapted to control the selection of the inputs of this multiplexer and, moreover, to control gating circuit 415. 
     The multiplexer control circuit shown in FIG. 10 is comprised of a set-reset (R/S) flip-flop circuit 1004, clocked flip-flop circuits 1010, 1016 and 1026, AND gates 1003, 1012 and 1014, NAND gates 1018 and 1020 and NOR gate 1024. Gating circuit 415 is comprised of a tape data latch circuit 1028, such as a Model LS173 4-bit latch circuit, and gates 1030. The set input S of R/S flip-flop circuit 1004 is connected to an OR gate 100 and is adapted to receive a set signal when the CPU is or is about to transmit data. The other input of OR gate 1002 is connected to the output of NOR gate 1024, the purpose of which will become apparent from the description set out below. 
     The signal provided at the output of NOR gate 1024 is used as the multiplexer control signal and is applied to lead 410 via an inverter 1032. It will be appreciated that the multiplexer control signal is a binary &#34;1&#34; when signals, referred to as DORQ 0 and DORQ 1 both are binary 1&#39;s; and the multiplexer control signal is a binary &#34;0&#34; when either of the DORQ 0 and DORQ 1 signals is a binary &#34;0&#34;. Multiplexer 406 is adapted to select its B inputs for the transmission of data supplied thereto when the multiplexer control signal is a binary &#34;1&#34; and to select its A inputs when the multiplexer control signal is a binary &#34;0&#34;. The reset input R of R/S flip-flop circuit 1004 is connected to an AND gate 1003 which is adapted to receive a binary &#34;1&#34; when the CPU is neither transmitting nor is about to transmit data, and also is adapted to receive the binary &#34;1&#34; supplied by buffer 416 to lead 418 when the contents of this buffer are &#34;empty&#34;. Thus, when buffer 416 is in condition to receive data and the CPU is not transmitting such data, AND gate 1003 resets flip-flop circuit 1004. 
     Clocked flip-flop circuit 1010 has its data input D connected to its Q output and, thus, is adapted to change its state, or &#34;toggle&#34;, in response to each positive transition supplied to its clock input CK. This clock input CK is connected to the Q output of flip-flop circuit 1026. The Q and Q outputs of flip-flop circuit 1010 are connected to respective inputs of AND gates 1012 and 1014, the other inputs of which are connected in common via an inverter 1016 to the Q output of flip-flop circuit 1004. AND gate 1012 is adapted to produce a signal, referred to herein as the DISPRQ 0 signal, for the duration that flip-flop circuit 1004 is reset, provided that flip-flop circuit 1010 is set. AND gate 1014 is adapted to produce the signal DISPRQ 1 for the duration that flip-flop circuit 1004 is reset, provided that flip-flop circuit 1010 also is reset. The DISPRQ 0 and DISPRQ 1 signals are adapted to be supplied to apparatus which is used to transmit the position data derived from the VTR&#39;s to gating circuit 415. Such apparatus is described in greater detail in copending application serial numbers (Serial No. 139748 and 139702). These DISPRQ signals represent that buffer 416 is in condition to receive such position data. 
     It is assumed, for the purpose of the present discussion, that the DISPRQ 0 signal enables the aforementioned apparatus to transmit position data derived from the recording VTR; and that the DISPRQ 1 signal is adapted to condition that apparatus to transmit the position data that is derived from the playback VTR. It is appreciated that the position data derived from the playback and recording VTR&#39;s are to be stored in different locations in RAM 424. These memory locations are defined by respective pre-set addresses generated by pre-set address generator 408 (FIG. 4A). To distinguish between the memory location associated with the playback and recording VTR&#39;s, the signal produced at the Q output of flip-flop circuit 1010 is supplied to pre-set address generator 408 to be included in the pre-set address word generated thereby. Thus, when the Q output of flip-flop circuit 1010 is a binary &#34;1&#34;, the pre-set address identifies a memory location in RAM 424 in which position data derived from the recording VTR is stored. Conversely, when the Q output of this flip-flop circuit is a binary &#34;0&#34;, pre-set address generator 408 is actuated to supply the A inputs of multiplexer 406 with the address identifying the location in RAM 424 in which the position data derived from the playback VTR is stored. 
     The aforementioned apparatus, when provided with position data derived from the playback and recording VTR&#39;s, responds to the DISPRQ 0 and DISPRQ 1 signals to supply acknowledgement signals to the apparatus illustrated in FIG. 10. More particularly, such apparatus supplies the DORQ 0 signal to one input of NOR gate 1024 when position data derived from the recording VTR is available to be stored in RAM 424. When position data derived from the playback VTR is available for storage, such apparatus supplies the DORQ 1 signal to the other input of NOR gate 1024. The output of this NOR gate is connected to the reset inputs R of clocked flip-flop circuits 1016 and 1026. 
     The clock input CK of flip-flop circuit 1016 is connected to receive a clock signal DISPCK which is synchronized with the timing signals used by the aforementioned apparatus in providing position data derived from the playback and recording VTR&#39;s. Normally, when such apparatus is not active, the DISPCK clock signal is at a relatively high level. The Q output of this flip-flop circuit is connected to the data input D thereof, such that flip-flop circuit 1016 changes state, or toggles, in response to, for example, the positive-going edge of each DISPCK clock signal. In addition, this Q output is connected to one input of NAND gate 1020 and the Q output of this flip-flop circuit is connected to an input of NAND gate 1018. The other inputs of NAND gates 1018 and 1020 are connected in common to receive the DISPCK signal via an inverter 1022. 
     The output of NAND gate 1020 is connected to the clock input CK of flip-flop circuit 1026. The data input D of this flip-flop circuit is connected to a source of positive potential, corresponding to a binary &#34;1&#34;, such that flip-flop circuit 1026 is triggered to its set state in response to the positive transition, for example, in the signal produced by NAND gate 1020, provided that the binary &#34;0&#34; reset signal is not applied to the reset input R thereof. The signal produced at the Q output of flip-flop circuit 1026 is supplied to multiplexer 406 to disable the operation thereof. That is, in response to this disable signal, neither the data provided at the A inputs nor the data provided at the B inputs of this multiplexer are transmitted therethrough. In the &#34;disable&#34; mode, the outputs of multiplexer 406 present a high impedance so as not to affect other circuitry connected thereto. 
     The position data derived from the playback and recording VTR&#39;s are provided in the form of successive 4-bit characters. The purpose of tape data latch circuit 1028 and gate 1030 is to store the first 4-bit character until the next-following 4-bit character is received, and then to transmit both characters as a single 8-bit word. It is appreciated that each 4-bit character represents a decimal digit of the position data. Tape data latch circuit 1028 is supplied with the 4-bit character derived from the VTR&#39;s and is adapted to temporarily store this character until the next-following 4-bit character is transmitted. To this effect, tape data latch circuit 1028 includes a clock input connected to receive the output of NAND gate 1018 as a clock signal, and a gate input connected to receive the signal provided at the Q output of flip-flop circuit 1026 as an enable, or gating circuit. Gates 1030 include a similar gating, or enable input connected to the Q output of flip-flop circuit 1026. 
     The manner in which the control circuit illustrated in FIG. 10 functions to control multiplexer 406 and to control gating circuit 415 now will be described with reference to the timing diagrams illustrated in FIGS. 11A-11L. Normally, the DORQ 0 and DORQ 1 signals exhibit their relatively high levels, and each is a binary &#34;1&#34;, as shown in FIGS. 11G and 11H. Consequently, the signal supplied to the reset input R of flip-flop circuits 1016 and 1026 is a binary &#34;0&#34; so as to maintain these flip-flop circuits in their respective reset states. The DISPCK clock signal supplied to the clock input CK of flip-flop circuit 1016 normally is at a high level and has no affect upon this flip-flop circuit, as shown in FIG. 11I. Since flip-flop circuit 1016 is maintained in its reset state, NAND gate 1020 is conditioned to apply &#34;clock&#34; signals (FIG. 11L) to the CK input of flip-flop circuit 1026. However, since flip-flop circuit 1026 also is maintained in its reset state (FIG. 11K), the &#34;enable&#34; signal is not applied to the tape data latch circuit or to gates 1030. These circuits thus remain inoperative. 
     Let it be assumed that the CPU is neither transmitting data nor is it about to transmit data. OR gate 1002 thus is supplied with a binary &#34;0&#34; at each of its inputs. Let it be further assumed that the contents of buffer 416 are &#34;empty&#34;, resulting in a binary &#34;1&#34; supplied from this buffer to AND gate 1003 via lead 418. The fact that the CPU is not transmitting data is represented by a binary &#34;1&#34; which is applied to the other input of AND gate 1003, resulting in the resetting of flip-flop circuit 1004, as shown in FIG. 11C. The Q output of this flip-flop circuit is provided with a binary &#34;0&#34;, which is inverted by inverter 1006 so as to condition AND gates 1012 and 1014. 
     Let it also be assumed that flip-flop circuit 1010 exhibits its set state, to produce a binary &#34;1&#34; at its Q output, as shown in FIG. 11D. This binary &#34;1&#34; is supplied to pre-set address generator 408 to establish a pre-set address in RAM 424, corresponding to the location in which position data of the recording tape is stored. Also, this binary &#34;1&#34; is supplied to AND gate 1012. AND gate 1012 now is supplied with a binary &#34;1&#34; at each input thereof so as to produce the DISPRQ 0 signal shown in FIG. 11E. 
     The DISPRQ 0 signal is supplied to apparatus from which the time code addresses read from the recording tape also are supplied. This apparatus, described in greater detail in the aforementioned copending applications, returns a binary &#34;0&#34; DORQ 0 signal, shown in FIG. 11G, if position data from the playback tape is available for storage in RAM 424. This negative transition actuates the circuitry shown in FIG. 10 to transfer such time code addresses to the RAM. In response to this negative transition in the DORQ 0 signal, NOR gate 1024 supplies a binary &#34;1&#34; to the reset input of each of flip-flop circuits 1016 and 1026, thereby enabling these flip-flop circuits to be toggled by positive transitions applied to their respective clock inputs CK. Also, after a suitable delay (not shown), the binary &#34;1&#34; produced by NOR gate 1024 sets flip-flop circuit 1004, as shown in FIG. 11C, thereby disabling AND gates 1012 (FIG. 11E) and 1014. Furthermore, the binary &#34;1&#34; output of NOR gate 1024 is inverted by inverter 1032 (FIG. 11B) to operate multiplexer 406 (FIG. 4A) to transfer the signals provided at its A input to buffer 416. Thus, for the duration of the negative pulse shown in FIG. 11B, the pre-set address generated by pre-set address generator 408 is transferred by multiplexer 406 to be supplied to address latch circuit 426. In this manner, the address word supplied to RAM 424 identifies the storage location therein in which position data derived from the recording tape is to be stored. 
     The first positive transition in the DISPCK clock signal (FIG. 11A) following the occurrence of the DORQ 0 signal toggles flip-flop circuit 1016 to its set state. Hence, the Q output thereof is supplied with a binary &#34;1&#34; as shown in FIG. 11I. It is appreciated that this flip-flop circuit continues to toggle in response to each successive positive transition in the DISPCK clock signal supplied thereto, provided NOR gate 1024 applies a binary &#34;1&#34; to its reset input R. Thus, NAND gates 1018 and 1020 are alternately enabled by the setting and resetting of flip-flop circuit 1016. When NAND gate 1020 is enabled, each negative half-cycle in the DISPCK clock signal is supplied to the clock input CK of flip-flop circuit 1026, as shown in FIG. 11L. It is recalled that, at the beginning of the operation described herein, flip-flop circuit 1026 exhibits its reset state. When the binary &#34;0&#34; reset signal applied to its reset input R by NOR gate 1024 terminates, the first positive transition in the pulses supplied to flip-flop circuit 1026 by NAND gate 1020 toggles this flip-flop circuit to its set state. Consequently, the Q output of this flip-flop circuit is provided with a binary &#34;1&#34; (FIG. 11K) to disable multiplexer 406. That is, when flip-flop circuit 1026 is set, the outputs of multiplexer 406 exhibit a relatively high impedance, and neither its A nor its B inputs are selected. It is appreciated that, in the absence of this disabling signal produced by flip-flop circuit 1026, the A inputs of the multiplexer would have been selected. 
     The binary &#34;1&#34; provided at the Q outputs of flip-flop circuit 1026 triggers flip-flop circuit 1010 to its reset state, as shown in FIG. 11D. This conditions AND gate 1014 to transmit the DISPRQ 1 signal when flip-flop 1004 next is reset. Also, the binary &#34;0&#34; at the Q output of flip-flop circuit 1026 serves as the &#34;enable&#34; signal for tape data latch circuit 1028 and gates 1030. The duration of this &#34;enable&#34; signal is determined by the duration of the DORQ 0 signal, shown in FIG. 11G. During this duration, the &#34;clock&#34; signal produced by NAND gate 1018 and supplied to tape data latch circuit 1028 serves to clock the time code addresses derived from the recording VTR into this tape data latch circuit. As an example, the 4-bit signal representing one decimal digit of the position data is clocked into tape data latch circuit in response to the positive transition of this &#34;clock&#34; signal, whereby this 4-bit signal is temporarily stored. At the next-following positive transition in this &#34;clock&#34; signal, the 4-bit signal stored in tape data latch circuit 1028 is read out therefrom concurrently with the receipt of the next 4-bit signal derived from the playback VTR and representing the next decimal digit of the time code address. This next 4-bit signal also is supplied to and gated through gates 1030, whereby an 8-bit data word, formed of the first and second 4-bit digital signals, is supplied from tape data latch circuit 1028 and gates 1030 to buffer 416. It is appreciated that this position data word next is transmitted from buffer 416 to be written into RAM 424 at the address previously generated by pre-set address generator 408 and now stored in address latch circuit 426, in a manner similar to that set out in detail hereinabove with respect to FIGS. 4A and 4B. 
     At the termination of the DORQ 0 signal (FIG. 11G), flip-flop circuits 1016 and 1026 are reset (FIGS. 11I and 11K), thereby restoring the circuitry illustrated in FIG. 10 to its initial condition, except that now, flip-flop circuit 1010 remains in its reset state, as shown in FIG. 11D. 
     When the contents of buffer 416 are &#34;empty&#34;, flip-flop circuit 1004 is reset once again, as shown in FIG. 11C, and the aforedescribed operation is repeated. Since flip-flop circuit now is reset (FIG. 11D), AND gate 1014 is enabled to produce the DISPRQ 1 signal shown in FIG. 11F. 
     This DISPRQ 1 signal is received by the apparatus which derives time code addresses from the playback VTR and, if such a time code address is available for storage in RAM 424, such apparatus returns the DORQ 1 signal to NOR gate 1024, as shown in FIG. 11H. The remaining circuitry illustrated in FIG. 10 responds to this DORQ 1 signal in the same manner as it had responded to the DORQ 0 signal, discussed above. Hence, the &#34;enable&#34; signal produced at the Q output of flip-flop circuit 1026 remains for the duration of the DORQ 1 signal, and the &#34;clock&#34; signal produced by NAND gate 1018 is as shown in FIG. 11J. The pre-set address generated by pre-set address generator 408 to identify the location in RAM 424 in which position data derived from the recording VTR is to be stored is transferred from the A inputs of multiplexer 406 to address latch circuit 426. Then, after RAM 424 is supplied with the appropriate address, the next-following 4-bit digital signal, representing one decimal digit of the position data derived from the recording tape is clocked into tape data latch circuit 1028, and this 4-bit digital signal is read-out therefrom in concurrence with the next-following 4-bit digital signal which is gated by gates 1030. Accordingly, the resultant 8-bit position data word, which represents two decimal digits of the recording tape time code address, is transferred to buffer 416 and thence to RAM 424 whereat it is stored in the addressed location. 
     It is appreciated that flip-flop circuit 1004 is reset when the CPU is not transmitting data and when buffer 416 is in condition to receive data. The resetting of this flip-flop circuit is used to apprise the apparatus from which time code addresses are derived from the playback and recording VTR&#39;s to transmit such time code addresses sequentially by digit. First the time code address derived from the recording tape is received and the time code address derived from the playback tape is received. Such time code addresses are transferred to RAM 424 in the form of successive position data words, each position data word being constituted by two 4-bit digital signals, each such 4-bit digital signal representing a respective time code address digit. The addresses supplied to RAM 424 during this mode of operation are derived from pre-set address generator 408. More particularly, the position data words derived from the playback tape are supplied to RAM 424 are preceded by the pre-set address word derived from pre-set address generator 408 to identify the first memory location into which the first position data word is stored. This address word, which is stored in address latch circuit 426, includes the aforedescribed control bit representing that this word is associated with position data. As mentioned above, this control bit controls the operation of counting circuit 432 and memory write generator 434, whereby the address word stored in the address latch circuit is incremented by one count after each playback tape position data word is written into the RAM. After all of the position data words derived from the recording tape have been written into respective addresses in RAM 424, this operation is repeated so as to write position data words derived from the playback tape into the RAM. As before, preceding the first position data word, pre-set address generator 408 supplies the pre-set address word, associated with the first storage location, to address latch circuit 426, this address word also containing the control bit that is supplied to counting circuit 432 via lead 436. After each position data word derived from the recording tape then is written into RAM 424, the address word stored in address latch circuit 426 is incremented by one count. 
     Thus, position data derived from the playback and recording tapes automatically are written into predetermined address locations in RAM 424 in the absence of specific control by the CPU. Of course, this operation is not carried out when the CPU transmits or is about to transmit data to the RAM. 
     Detailed schematic diagrams of portions of the circuitry which have been discussed above with respect to the block diagrams of FIGS. 3-5 are set out in copending application serial number 139,444, filed Apr. 11, 1980 Serial No. 139444, which application is incorporated herein by reference. 
     CPU Control Over the Agenda-Edit Operation 
     Referring now to FIGS. 12A-12C, there is illustrated a flow chart of the programmed routine carried out by the CPU to control an agenda-edit operation in response to the coded representations of the identities of respective register and signal selector switches which are transmitted to the CPU by the circuitry discussed above with respect to FIG. 3. This routine, to be described, also controls the indicators which are associated with respective ones of signal selector switches V, A-1 and A-2. Although not described specifically herein, reference is made to copending application (attorneys&#39; docket number SO1275) for an explanation as to the manner in which the CPU controls the transfer of data between display registers on console 10 and further controls the manner in which the indicators and displays are selectively energized. 
     The flow chart shown in FIGS. 12A-12C will be explained in conjunction with particular operations of the signal selector switches V, A-1 and A-2 and selected register selector switches, all provided on console 10. As represented by this flow chart, the CPU awaits the arrival of a character representing the identity of a particular switch which has been operated on console 10. This character is produced by the apparatus discussed above in respect to FIG. 3. When this character is received by the CPU, it is examined to determine if it represents a signal selector switch V, A-1 or A-2. If not, the CPU continues with its examination to determine if this character represents a register selector switch. As shown in FIG. 12A, if this character represents neither a signal selector switch nor a register selector switch, the programmed routine branches to a different routine which, for example, may be the error detecting routine described hereinbelow with reference to FIGS. 14A-14D. However, if it is determined that the received character identifies a register selector switch, then it is determined whether this is the first console switch which has been operated. If this is not the first switch to have been operated, that is, if an operation already is pending due to the prior operation of a switch, then the programmed routine branches to the so-called register transfer routine. This register transfer routine is disclosed in detail in copending application (Ser. No. 139444), which disclosure is incorporated herein by reference. 
     If, however, the CPU programmed routine determines that the received character identifies a register selector switch and that an operation already is pending, the next inquiry is made as to whether an &#34;assign&#34; flag has been set. The setting of an &#34;assign&#34; flag is described below with respect to FIG. 12B. For the present description, it is sufficient to appreciate that the &#34;assign&#34; flag is set if an agenda-edit operation has been initiated, such as by the prior operation of a signal selector switch V, A-1 or A-2. As shown in FIG. 12A, if this &#34;assign&#34; flag has not been set, the programmed routine branches to the aforementioned register transfer routine. But, if the &#34;assign&#34; flag has been set, the agenda-edit routine continues, as will be described below. 
     Let it be assumed that the operator wishes to initiate the agenda-edit operation, whereby particular addresses, or positions, on the recording tape are selected to define corresponding split-in points. Typically, the position data displayed in IN register 80 (FIG. 1) represents the first edit-in point at which the video or audio signals (the latter being audio, cue or other signals recorded in the first or second audio tracks) are transferred to, or re-recorded on, the recording tape. The position data displayed in EVENT-1 and EVENT-2 registers 118 and 126 represent the following points on the recording tape, not necessarily in this order, at which video or audio signals are transferred thereto. It is assumed that SPLIT-OUT switch 136 has not been operated and, therefore, the operator now is establishing respective split-in edit points at which the respective video and audio signals are to be transferred from the playback tape to the recording tape. 
     The character representing the particular signal selector switch V, A-1 or A-2 which has been operated is received by the CPU. This character is recognized, as shown in FIG. 12A, as representing the identity of a signal selector switch, and the programmed routine continues (to FIG. 12B) so as to set the &#34;operation pending&#34; flag. This, of course, means that an operation now is in progress, as selected by the operator in accordance with the particular switch that has been actuated. After the &#34;operation pending&#34; flag is set, the CPU determines whether the indicator lamps associated with the received character are flashing. That is, if the received character represents video selector switch 112, the CPU inquires as to whether the indicator lamps associated with this video selector switch are flashing. This inquiry is made by sensing the indicator data word stored in the appropriate CPU memory location which is associated, or reserved, for the video switch indicators. Of course, if the received character represents A-1 switch 114 or A-2 switch 116, a similar operation is carried out by the CPU in order to determine whether the indicator lamps associated with these switches are flashing. 
     The CPU memory stores the position data displayed in each display register of console 10 and also stores the indicator data words for the respective indicators provided on the console. This data is stored in locations that are in correspondence with the display registers and console indicators. This portion of the CPU memory may, therefore, be considered to be a duplicate version of RAM 424. 
     Let it be assumed that the indicator lamps associated with the switch which is identified by the received character are not flashing. The CPU then causes these lamps, i.e. the upper and lower lamps associated with the operated signal selector switch, to flash. It is appreciated that this is attained by transmitting from the CPU to the apparatus illustrated in FIGS. 4A and 4B an address word to identify the location in RAM 424 in which the indicator word associated with the operated signal selector switch is stored, this address word being followed by an indicator data word which, when read out of the RAM, causes the indicator lamps associated with this signal selector switch to flash. The particular indicator data word and circuitry which is used to energize these indicator lamps have been discussed above. A similar indicator data word is written into the corresponding location in the CPU memory. The CPU then sets the &#34;assign&#34; flag to indicate that an agenda-edit operation now is being established. Then, the programmed routine returns to its START condition awaiting the arrival of the next-following character from the apparatus shown in FIG. 3. 
     Let it be assumed that the operator, after actuating one of the signal selector switches, desires to clear that switch so as not to assign the particular signals (i.e. video or audio signals) associated with that switch to position data. This &#34;clearing&#34; of the previously actuated switch avoids transferring the signals associated with that switch to the recording tape. To clear a previously actuated switch, the operator actuates that very same switch once again. As shown in FIG. 12A, the character representing the identity of this re-actuated switch is received and is identified as a signal selector switch character. Continuing to FIG. 12B, the &#34;operation pending&#34; flag is set in response to receipt of this character. Of course, it is recognized that, in the present example, the &#34;operation pending&#34; flag already has been set. 
     In accordance with this example, it is assumed that, since the V, A-1 or A-2 switch has been re-actuated by the operator, its associated indicator lamps are flashing at this time. Hence, the inquiry as to whether the associated indicator lamps are flashing is answered in the affirmative. Consequently, these indicator lamps, that is, the upper and lower lamps associated with this particular signal selector switch, are deenergized, or turned off. Moreover, since SPLIT-OUT switch 136 has not been operated, that is, a split-in edit mode has been selected, the entry of the previously actuated signal selector switch in an &#34;IN&#34; assignment table is cleared therefrom. The &#34;IN&#34; assignment table is described below. 
     The programmed routine then inquires as to whether any other indicator lamps associated with the remaining signal selector switches are flashing. If so, the routine returns to its START condition awaiting the arrival of the next-following character. However, if no other indicator lamps associated with the remaining signal selector switches are flashing, the &#34;assign&#34; and &#34;operation pending&#34; flags, which had been set in response to the initial actuation of the particular signal selector switch which now has been cleared, are cleared. The CPU then returns to its START condition. 
     Let it be assumed that only one of signal selector switches 112, 114 and 116 has been actuated, and that the operator intends to transfer the signals associated with this switch (i.e. the video or audio signals) to the recording tape. It is appreciated, therefore, that the indicator lamps associated with this particular signal selector switch are flashing so as to apprise the operator that this switch has been actuated. Furthermore, both the &#34;operation pending&#34; and the &#34;assign&#34; flags are set. The operator now selects the particular edit-in location on the recording tape at which transfer of these signals is to commence. This selection is obtained by the actuation of edit-in switch 82, EVENT-1 switch 120 or EVENT-2 switch 128. When the selected one of these register selector switches is operated, the apparatus illustrated in FIG. 3 supplies a character representing the identity of this operated switch to the CPU. It may be appreciated that this character serves not only to represent the identity of the register selector switch which has been operated, but also serves to identify the display register associated therewith. 
     As shown in FIG. 12A, this character is received by the CPU, is recognized as not representing the identity of any of signal selector switches V, A-1 or A-2, and, since it is representative of a register selector switch, and both the &#34;operation pending&#34; and &#34;assign&#34; flags are set, the programmed routine advances to FIG. 12C. 
     It is recalled that, in accordance with the present example, it is assumed that SPLIT-OUT switch 136 has not been operated. That is, it is assumed that the operator now is setting up, or establishing the parameters attendant a split-in edit mode. Thus, the inquiry as to whether a split-out edit mode has been selected is answered in the negative. The next-following inquiry is intended to ascertain whether edit-in switch 52, edit-in switch 82, or either of the EVENT switches has been operated. To be consistent with the requirements of a split-in edit assignment, only these four register selector switches should be operated. If the received character represents the identity of any other register selector switch, such as an edit-out switch, a mark enable switch, or the like, the program recognizes such a switch as being inconsistent with the split-in edit assignment mode, and the CPU returns to its START condition. However, in the present example, it is assumed that the received character represents the identity of edit-in switch 82 or EVENT-1 switch 120 or EVENT-2 switch 128, all of these being proper register selector switches. 
     In response to the operation of one of these register selector switches, the CPU now functions to associate the selected signal selector switch with the selected register selector switch or, more accurately, to associate the selected signal selector switch with the position data displayed in the corresponding display register. The purpose of this association is to assign the signal selector switch to a particular edit-in point, whereby the signals associated with that signal selector switch are transferred to the recording tape when the recording tape reaches that assigned edit-in point. This association, or assignment of the signal selector switch with the edit-in point is carried out by detecting which of the signal selector indicator lamps is flashing and then assigning the selected edit-in point to that signal selector switch. This detection of the flashing signal selector lamps is carried out by scanning the video (V), audio-1 (A-1) and audio-2 (A-2) indicator lamps, in order, until the flashing lamps are sensed. To effect such a scanning mode, each of these indicator lamps arbitrarily is designated by a particular count of a counter. For example, a count of 0 designates the video (V) indicator lamps, a count of 1 designates the audio-1 (A-1) indicator lamps and a count of 2 designates the audio-2 (A-2) indicator lamps. As shown in FIG. 12C, once it is ascertained that the received character representing the identity of a register selector switch is a proper register selector switch, the count (i) of the counter is reset to a count of 0 (i=0). Then, the inquiry is made as to whether the signal selector indicator lamp associated with this count is flashing. Since this count now is 0, and since a count of 0 designates the video (V) indicator lamps, the inquiry is made as to whether the video (V) indicator lamps are flashing. It is recalled that these indicator lamps will be flashing if the operator had actuated the video (V) selector switch in connection with the assignment of a particular edit-in point for the video signal. 
     If it is determined that the signal selector indicator lamps designated by the count of 0 (i=0) are not flashing, that is, if it is determined that the video indicator lamps are not flashing, the count of the aforementioned counter is incremented by unity (i=1), and then, if the incremented count is not yet equal to 3, inquiry is made as to whether the signal selector indicator lamps associated with this incremented count are flashing. In the present example, the incremented count is equal to 1, and this count designates the audio-1 (A-1) indicator lamps. If it is determined that these indicator lamps also are not flashing, then the count is incremented by unity once again, and the foregoing process is repeated. That is, in accordance with the present example, the count is incremented to a count of 2, which designates the audio-2 (A-2) indicator lamps. If these indicator lamps are not flashing, the count is incremented further, and now is equal to a count of 3. Once this count of 3 (i=3) is reached, the &#34;assign&#34; and &#34;operation pending&#34; flags are cleared, and the CPU returns to its START condition awaiting the arrival of the next character. 
     Consistent with the present example, it is assumed that the indicator lamps associated with one of the video, audio-1 or audio-2 selector switches is flashing. Hence, during the scanning operation mentioned above, that is, when the count i is equal to 0, 1 or 2, the inquiry as to whether the designated indicator lamps are flashing will be answered in the affirmative. Then, since the split-out mode has not been selected, the received character, which represents the identity of a register selector switch (and, thus, its associated display register) is linked, or assigned, with the character representing the signal selector switch whose indicator lamps are flashing. This assignment is made in the &#34;IN&#34; assignment table, which comprises a portion of the CPU memory having locations defined by the V, A-1 and A-2 characters. If, for example, the video (V) indicator lamps are flashing, and if the received character represents edit-in switch 82 (or IN register 80), then the character representing the record IN register (referred to as the record IN character) and the character representing the video selector switch (referred to as the video (V) character) are linked with each other. This may be achieved by storing the record IN character in the &#34;IN&#34; assignment table at the address, or location, corresponding to the video (V) character, as shown in FIG. 13. Alternatively, if the audio-1 indicator lamps were flashing, and if the received character represents the EVENT-1 selector switch (and, thus, the EVENT-1 display register), then the EVENT-1 character is linked with the audio-1 character, that is, the EVENT-1 character is stored in the &#34;IN&#34; assignment table at a location corresponding to the audio-1 character. 
     The programmed routine, illustrated in FIG. 12C, then inquires as to whether this received register selector switch character represents the identity of the play IN or record IN selector switches (or display registers), or the play OUT or record OUT selector switches (or display registers). If so, then both the upper and lower indicator lamps associated with the linked signal selector character (i.e. the linked V, A-1 or A-2 character) are energized continuously. If it is determined that the received character does not represent the identity of the play/record IN or OUT selector switch (or display register), the CPU inquires as to whether this character represents the identity of the EVENT-1 selector switch (or display register). If so, then the upper indicator lamp associated with the signal selector character (i.e. the character identifying the V, A-1 or A-2 selector switch) is energized and the lower indicator lamp associated with this selector switch is de-energized. However, if the received character does not represent the identity of the EVENT-1 selector switch (or display register), then it is assumed that this character represents the identity of the EVENT-2 selector switch (or display register), and the signal selector switch which is identified by the character linked thereto has its lower indicator lamp associated therewith energized, and its upper indicator lamp de-energized. 
     After the appropriate indicator lamp (or lamps) is energized, the count of the aforementioned counter is incremented, and this process is repeated. Ultimately, the count is incremented to a count of 3 (i=3), whereupon the proper indicator lamps will be energized, both the &#34;assign&#34; and &#34;operation pending&#34; flags will be cleared, and the CPU returns to its START condition awaiting the arrival of the next character. 
     The foregoing routine is carried out to set up, or establish, the parameters associated with a split-in edit mode, and also to set up, or establish, the parameters associated with a split-out edit mode. A specific example now will be described, wherein it is assumed that the video signals are to be transferred when the recording tape reaches the location corresponding to the position data displayed in record IN register 80, the audio-1 signals are to be transferred when the recording tape reaches the location corresponding to the position data displayed in EVENT-1 register 118, and the audio-2 signals are to be transferred when the recording tape reaches the location corresponding to the position data displayed in EVENT-2 register 126. Since these parameters relate to the split-in edit point, SPLIT-OUT switch 136 is not actuated. 
     The operator first operates video switch (V) 112. As discussed above, the character representing the identity of this video switch is received and is identified as a signal selector character. As shown in FIG. 12B, once this character is recognized, the &#34;operation pending&#34; flag is set. It has been assumed that video switch 112 is the first signal selector switch to be operated and, therefore, no other signal selector indicator lamps are flashing. Consequently, both the upper and lower indicator lamps associated with the video switch are flashed, in the manner described above, and the &#34;assign&#34; flag is set. The CPU then returns to its START condition to await the arrival of the next-following character. 
     Once the indicator lamps associated with video switch 112 are flashed, the location in the &#34;IN&#34; assignment table corresponding to the character representing the identity of this switch is addressed. The operator now should select a register selector switch, whereby the position data displayed in the register associated with that switch will be linked, or assigned, with the video switch. In accordance with the example assumed herein, the operator now actuates edit-in switch 82. Accordingly, the CPU receives the character representing the identity of this edit-in switch, which, for the purpose of the present discussion, also represents the identity of record IN register 80. Since both the &#34;operation pending&#34; and &#34;assign&#34; flags have been set, the programmed routine advances to that portion of the flow chart shown in FIG. 12C. The inquiry as to whether the split-out mode has been selected is answered in the negative and, since the received character is proper, or legitimate (i.e. it represents either the play/record IN or an EVENT register), the programmed routine continues, resetting the aforementioned counter to a count of 0 (i=0). This count designates the indicator lamps associated with video switch 112, and the inquiry as to whether the indicator lamps are flashing is answered in the affirmative. Then, since the split-out mode has not been selected, the received character, which represents the record IN register, is linked to the character representing the video (V) switch and, as shown in FIG. 13, the record IN character is stored in the &#34;IN&#34; assignment table at a location corresponding to the video (V) character. 
     This received register selector character represents the record IN register and, since this register is designated as having the highest priority because the position data displayed therein represents the first edit-in point on the recording tape, the CPU energizes both the upper and lower indicator lamps associated with video switch 112. 
     Now, the count (which had been equal to 0) is incremented so as to be equal to 1 (i=1). This count of 1 designates the indicator lamps associated with audio-1 switch 114. Since the audio-1 switch had not been actuated, its associated indicator lamps are not flashing. Consequently, the count is incremented once again so as to be equal to 2 (i=2). This count designates the indicator lamps associated with audio-2 switch 116. These indicator lamps also are not flashing, and the count now is further incremented so as to be equal to 3 (i=3). When this count is attained, the &#34;assign&#34; and &#34;operation pending&#34; flags are cleared; and the CPU returns to its START condition. 
     At this stage in establishing the parameters of the split-in mode, the video switch V is linked to the record IN register, which means that when the recording tape is advanced to the edit point corresponding to the position data displayed in the record IN register, transfer of the video signals from the playback tape to the recording tape will commence. 
     Consistent with the example described herein, the operator next actuates audio-1 (A-1) switch 114. The character representing the identity of this A-1 switch is received by the CPU, is recognized as being a signal selector character and, as shown in FIG. 12B, the &#34;operation pending&#34; flag is set. Since the indicator lamps associated with the A-1 switch are not flashing at this time, the CPU causes both the upper and lower lamps now to flash, and the &#34;assign&#34; flag is set. The manner in which the CPU effects the energization of these lamps has been described above. In addition to setting the &#34;assign&#34; flag, the character representing the A-1 switch addresses a corresponding location in the &#34;IN&#34; assignment table. The CPU then returns to its START condition. 
     Next, the operator actuates EVENT-1 switch 120. The character representing this switch is received by the CPU, is recognized as identifying a register selector switch and, since both the &#34;operation pending&#34; and &#34;assign&#34; flags are set, the programmed routine advances to FIG. 12C. The inquiry as to whether the split-out mode has been selected is answered in the negative. Furthermore, since the received register selector character represents a proper, or legitimate, register (that is, it represents the EVENT-1 register), the counter is set to a count of 0 (i=0). This count designates video (V) switch 112, and the inquiry as to whether the indicator lamps associated with this switch are flashing is answered in the negative. It is recalled that the indicator lamps associated with the video switch both have been energized to apprise the operator that this switch is associated with record IN register 50. 
     Since the indicator lamps associated with the signal selector switch designated by the count of 0 are not flashing, this count is incremented to a count of 1 (i=1). This count of 1 designates A-1 switch 114 whose associated indicator lamps both are flashing. Since the split-out mode has not been selected, the received character representing the EVENT-1 register is linked to the character representing the A-1 switch, and the EVENT-1 character is stored in the &#34;IN&#34; assignment table at the location corresponding to the audio-1 character, as shown in FIG. 13. 
     Proceeding with the routine shown in FIG. 12C, since this received register selector character does not represent any of the play IN, record IN, play OUT or record OUT registers, the inquiry is made as to whether this character represents the EVENT-1 register. This inquiry is answered in the affirmative, and the upper indicator lamp associated with the A-1 switch (whose character is linked to the EVENT-1 character stored in the &#34;IN&#34; assignment table) is energized and the lower lamp thereof is de-energized. This apprises the operator that the A-1 switch is linked to the EVENT-1 register; which means that when the recording tape is advanced to the edit-in point represented by the position data stored in EVENT-1 register 118, transfer of the audio-1 signals to the recording tape will commence. 
     After the indicator lamps associated with the A-1 switch are suitably energized, the count is incremented to a count of 2 (i=2), which count designates lamps associated with the A-2 switch. Inquiry is made as to whether the indicator lamps associated with this A-2 switch are flashing. Since such indicator lamps are not flashing, the count is incremented to a count of 3 (i=3); whereupon both the &#34;assign&#34; and &#34;operation pending&#34; flags are cleared, and the CPU returns to its START condition. 
     The final parameter to be established for the split-in mode is to link or assign the A-2 switch with an edit-in point on the recording tape. To achieve this, the operator actuates audio-2 switch 116 resulting in the transmission of a character representing the identity of this A-2 switch to the CPU. As shown in FIG. 12A, this character is received and is recognized as identifying the A-2 switch. The routine advances to the flow chart shown in FIG. 12B, wherein the &#34;operation pending&#34; flag is set. Since the indicator lamps associated with this A-2 switch are not flashing, the CPU causes such lamps to flash, in the manner described hereinabove, and then the &#34;assign&#34; flag is set. In addition, the character representing this A-2 switch addresses a corresponding location in the &#34;IN&#34; assignment table. The CPU then returns to its START condition. 
     The operator next actuates EVENT-2 switch 128, whereby the character which represents the identity of this EVENT-2 switch is transmitted to the CPU. This character is received and is recognized as identifying a register selector switch. Since both the &#34;operation pending&#34; and &#34;assign&#34; flags are set, the routine continues in accordance with the flow chart shown in FIG. 12C. The inquiry as to whether the split-out mode has been selected is answered in the negative. The next-following inquiry as to whether the received character identifies a play or record IN or an EVENT register is answered in the affirmative, and the counter is set to a count of 0 (i=0). 
     This count designates video switch 112 as the signal selector switch whose associated indicator lamps are examined. These indicator lamps are not flashing and, therefore, the count of the aforementioned counter is incremented to a count of 1 (i=1). This count designates the A-1 switch whose associated indicator lamps are examined. Since these indicator lamps also are not flashing, the count is incremented again to a count of 2 (i=2). This designates the A-2 switch whose associated indicator lamps are, at the present time, flashing. Accordingly, the inquiry is made as to whether the split-out mode has been selected. This inquiry is answered in the negative, whereby the character representing the identity of the EVENT-2 register is linked, or assigned, with the character representing the identity of the A-2 switch, and the EVENT-2 character is stored in the &#34;IN&#34; assignment table at the location corresponding to the audio-2 character, as shown in FIG. 13. 
     After the signal selector and display register characters are linked, inquiry is made as to whether the display register character is the play IN, record IN, play OUT or record OUT character. This inquiry is answered in the negative and the next-following inquiry as to whether this display register character identifies the EVENT-1 register also is answered in the negative. It is concluded, therefore, that this display register character represents the EVENT-2 register. Consequently, the upper indicator lamp associated with the A-2 switch is deenergized, and the lower indicator lamp associated therewith is energized. 
     After the indicator lamps associated with the A-2 switch are suitably energized, the count of the counter is incremented to a count of 3 (i=3), whereupon both the &#34;assign&#34;  and &#34;operation pending&#34; flags are cleared. The CPU then returns to its START condition. 
     As a result of the foregoing operations, both the upper and lower indicator lamps associated with the V switch are energized, only the upper indicator lamp associated with the A-1 switch is energized, and only the lower indicator lamp associated with the A-2 switch is energized. These indicator lamps thus apprise the operator of the order in which the display registers are selected, and the position data therein represent the locations at which the respective signals will be transferred to the recording tape during an actual edit operation. More particularly, this order appears as: the signals selected by the signal switch having both indicator lamps energized will be transferred at the edit-in point represented in IN register 80, the signals selected by the signal selector switch having its upper indicator lamp energized will be transferred at the edit-in point represented in EVENT-1 register 118, and the signals selected by the signal selector switch having its lower indicator lamp energized will be transferred at the edit-in point represented in EVENT-2 register 126. In the present example, this means that first the video signals will be transferred, then the audio-1 signals will be transferred, and finally the audio-2 signals will be transferred. If the edit-in point represented in EVENT-2 register 126 precedes the edit-in point represented in EVENT-1 register 118, then the audio-2 signals will be transferred before the audio-1 signals. From the foregoing, it is appreciated that the signal selector switch whose indicator lamps both are energized is linked to, or assigned with, the play IN register. The signal selector switch whose upper indicator lamp is energized is linked to, or assigned with, the EVENT-1 register. The signal selector switch whose lower indicator lamp is energized is linked to, or assigned with, the EVENT-2 register. 
     It may be appreciated that the order in which the respective signal selector switches are linked to the play IN, EVENT-1 and EVENT-2 registers is arbitrary. That is, although the foregoing has assumed that first the V switch is linked to the play IN register, and then the A-1 switch is linked to the EVENT-1 register, and then the A-2 switch is linked to the EVENT-2 register, it is possible that first the A-1 switch may be linked to the EVENT-1 register, and then the V switch may be linked to the play IN register, and then the A-2 switch may be linked to the EVENT-2 register. Nevertheless, this will not disturb the order in which the respective signals are transferred to the recording tape. That is, the signals will be transferred in the order of the position data displayed in the display registers linked thereto, whereby the particular order in which the signals are transferred is a function of the position data in the particular display registers to which the respective signal selector switches are linked. Consequently, if desired, the A-1 switch may be linked to the play IN register, the V switch may be linked to the EVENT-1 register and the A-2 switch may be linked to the EVENT-2 register. Any other desired linking, or assignments of the respective signal selector switches to these display registers may be selected. 
     The foregoing has described the manner in which the various edit-in parameters have been established for the split-in edit mode. More particularly, the edit-in points for the respective video and audio signals have been determined as a function of the positions of the recording tape. If desired, these parameters may be established as a function of the positions of the playback tape. In that event, it is assumed that the EVENT-1 and EVENT-2 registers display position data that has been derived from the playback tape. The locations in the &#34;IN&#34; assignment table corresponding to the signal selector characters, in which are stored the linked register selector characters, then will represent the play IN, EVENT-1 and EVENT-2 registers. Each of these register selector characters may be linked or assigned, with any desired signal selector character. Furthermore, a particular register selector character may be linked to two or even three signal selector characters. In that event, the signals which are selected by those signal selector characters will be transferred when the recording tape reaches the assigned edit-in point. For example, if the character representing the A-1 switch is linked with the character representing the EVENT-1 register, and if the characters representing the V and the A-2 switches both are linked to the character representing the record IN register, then the upper and lower indicator lamps associated with the V and with the A-2 switches will be energized, thereby apprising the operator that the video and audio-2 signals will be transferred first, and they will be transferred simultaneously when the playback tape reaches the edit-in point represented by the position data displayed in the play IN register; and the upper indicator lamp associated with the A-1 switch will be energized so as to apprise the operator that the audio-1 signals will be transferred when the playback tape reaches the edit-in point corresponding to the position data displayed in the EVENT-1 register. Of course, other various combinations or permutations of the foregoing may be selected, as desired, such that the video and audio signals may be transferred from the playback tape to the recording tape when one or the other of these tapes reaches the respective edit-in points with which the video and audio signals are assigned. 
     Establishing the parameters of a split-out edit mode are achieved in a manner which is substantially similar to that described above. As an example, let it be assumed that transfer of the audio-1 signals are to terminate when the recording tape reaches a location corresponding to the position data displayed in the record OUT register, transfer of the video signals should terminate when the recording tape reaches the location corresponding to the position data displayed in the EVENT-1 register, and transfer of the audio-2 signals should terminate when the recording tape reaches the location corresponding to the position data displayed in the EVENT-2 register. These parameters may be established by actuating the A-1 switch and then edit-out switch 86; by actuating the V switch and then EVENT-1 switch 120, and by actuating the A-2 switch and then EVENT-2 switch 128, either in this order or in any alternative order. 
     To establish this split-out mode, SPLIT-OUT switch 136 is operated. Then, the operator may actuate, for example, the V switch. It is appreciated that the CPU is supplied with a character representing the identity of this V switch, and after this character is recognized, the routine continues to the flow chart shown in FIG. 12B. The &#34;operation pending&#34; flag is set, and since the indicator lamps associated with this V switch are not flashing, the CPU now causes such indicator lamps to flash. The &#34;assign&#34; flag then is set, and this character representing the V switch is stored temporarily in the &#34;OUT&#34; assignment table. The CPU then returns to its START condition. 
     Next, the operator actuates EVENT-1 switch 120. The character representing this EVENT-1 switch is received by the CPU, is recognized as a character that represents the identity of a register selector switch and, since both the &#34;operation pending&#34; and &#34;assign&#34; flags are set, the routine advances to the flow chart shown in FIG. 12C. 
     The inquiry as to whether the split-out mode has been selected now is answered in the affirmative. Then, the character representing the register selector switch is recognized as being a proper character, that is, it is a character included in the group consisting of the play OUT, record OUT, and EVENT characters. If this received character had not been included in that group, the CPU ignores it and returns to its START condition. 
     Since the received selector character is recognized as being a proper character, the count of the counter is set to 0 (i=0). This count designates the V switch, and the inquiry is made as to whether the indicator lamps associated with this V switch are flashing. In the present example, such indicator lamps are flashing and, since the split-out mode has been selected, the received register selector character is linked to this character representing the V switch, and the EVENT-1 character is stored in the &#34;OUT&#34; assignment table at the location corresponding to the V character, as shown in FIG. 13. 
     Next, the register selector character is recognized as being neither a play IN, a play OUT, a record IN, or a record OUT character. Accordingly, the next-following inquiry is made as to whether this character identifies the EVENT-1 register. In the present example, this inquiry is answered in the affirmative, and the upper indicator lamp associated with the V switch (whose representative character is linked to this EVENT-1 character) is energized and the lower indicator lamp associated therewith is de-energized. Thus, the operator is apprised of the fact that the V switch is linked with the EVENT-1 register. This means that when the recording tape reaches the edit-out point corresponding to the position data displayed in the EVENT-1 register, transfer of the video signals to the recording tape will terminate. That is, further video signals no longer will be recorded. 
     The operator then may actuate the A-1 switch, whereby the character identifying this switch is received by the CPU and is recognized; and the CPU causes the upper and lower indicator lamps associated with this A-1 switch to flash. If the operator then actuates edit-out switch 86, the CPU receives the character identifying this switch (which also identifies the record OUT register) and, since this is a proper register to be selected, for this split-out mode, the count of the counter is set to 0 (i=0). This count designates the V switch whose associated indicator lamps now are not flashing. Consequently, the count of this counter is incremented to a count of 1 (i=1) to designate the A-1 switch. Since the indicator lamps associated with this A-1 switch are flashing, the received record OUT character is linked to the A-1 character, and the record OUT character is stored in the &#34;OUT&#34; assignment table at the location corresponding to the A-1 character, as shown in FIG. 13. Since the register selector character is the record OUT character, both the upper and lower indicator lamps associated with the A-1 switch (whose representative character is linked with this record OUT character) are energized. This apprises the operator that when the recording tape reaches the edit-out point corresponding to the position data displayed in the record OUT register, recording of the audio-1 signals will terminate. 
     Next, the count of the counter is incremented to a count of 2 (i=2), which designates the A-2 switch. Since the indicator lamps associated with this designated switch are not flashing, the count of the counter is incremented to 3 (i=3), and then the &#34;assign&#34; and &#34;operation pending&#34; flags are cleared. The CPU then returns to its START condition. 
     The final parameter to be established in this split-out mode is to link the A-2 switch with the EVENT-2 register. This is achieved in a manner similar to that described hereinabove, whereby the character representing the A-2 switch is linked with the character representing the EVENT-2 register, and the EVENT-2 character is stored in the &#34;OUT&#34; assignment table at the location corresponding to the A-2 character, shown in FIG. 13. In consequence thereof, the lower indicator lamp associated with the A-2 switch is energized and the upper indicator lamp associated therewith is de-energized. This apprises the operator that the audio-2 signals no longer will be recorded when the recording tape reaches the split-out point corresponding to the position data displayed in the EVENT-2 register. 
     Let it be assumed that, after establishing the foregoing parameters, the operator wishes to modify one of these parameters. For example, let it be assumed that the edit-out point for the audio-2 signals should be changed. This may be achieved as follows: 
     The operator actuates the A-2 switch, resulting in the flashing of the upper and lower indicator lamps associated with this switch, as has been described above. The operator now re-actuates the A-2 switch. When the character representing the identity of this re-actuated A-2 switch is received by the CPU, it is recognized, and the routine continues in accordance with the flow chart shown in FIG. 12B. The inquiry as to whether the indicator lamps associated with this A-2 character are flashing is answered in the affirmative. The CPU then directs that the upper and lower lamps associated with this A-2 switch are de-energized. The manner in which this is achieved has been described above. 
     Since the split-out mode has been selected, the entry of the character representing the EVENT-2 register is cleared from the A-2 location in the &#34;OUT&#34; assignment table. From FIG. 13, it is appreciated that the character representing the A-2 switch no longer is linked to the character representing the EVENT-2 register. Next, the inquiry is made as to whether any other indicator lamps are flashing. Since no other indicator lamps are flashing, both the &#34;assign&#34; and &#34;operation pending&#34; flags are cleared, and the CPU returns to its START condition. 
     The contents of EVENT-2 register 126 now may be modified, as desired, in the manner described in detail in the aforementioned copending application (Ser. No. 139,444). Once the operator is satisfied with the position data now displayed in EVENT-2 register 126, the edit-out point for the audio-2 signals may be obtained in the manner described above. 
     The manner in which the agenda-edit operation is carried out in accordance with the selected edit-in and edit-out points that are stored in the &#34;IN&#34; and &#34;OUT&#34; assignment tables now will be described with reference to FIG. 13. This figure represents the aforedescribed &#34;IN&#34; assignment table 1302 and the aforedescribed &#34;OUT&#34; assignment table 1304. These assignment tables preferably are portions of the CPU memory, which memory as mentioned above, further includes a portion in which the position data displayed in each of the position registers of console 10 are stored. This additional section of the CPU memory is referred to herein as a position data store 1306 having a plurality of individual locations, each of which corresponds to a respective display register, and each of which stores the position data that is displayed in its corresponding display register. For example, as shown in FIG. 13, position data store 1306 stores the record IN position data, which corresponds to the position data displayed in record IN register 80. The position data store also stores the play IN position data, which corresponds to the position data displayed in play IN register 50. Similarly, position data store 1306 stores the EVENT-1 position data (determined for both the edit-in and edit-out points), the EVENT-2 position data (also determined for the edit-in and edit-out points) and the record OUT position data, this data corresponding to the position data displayed in the EVENT-1, EVENT-2 and record OUT registers, respectively. Each location in position data store 1306 may be addressed, and each address corresponds to, for example, a respective display register. The EVENT position data is referred to as EVENT (in) or EVENT (out) data. 
     FIG. 13 also illustrates a present position register 1308, a comparator 1310, a read-out address generator 1312 and a record control arrangement 1314. Present position register 1308 is adapted to receive the position data derived from the recording tape. This position data supplied to the present position register corresponds to the position data that is supplied to and displayed in tape timer register 88. 
     Comparator 1310 is coupled to present position register 1308 and to position data store 1306. The purpose of this comparator is to compare position data in present position register 1308 to the position data stored in position data store 1306. That is, comparator 1310 functions to detect when the recording tape reaches an edit-in or edit-out point, which points are represented by the position data stored in the respective locations in position data store 1306. Read-out address generator 1312 is coupled to position data store 1306 to read out sequentially the position data stored in the individual locations therein. When comparator 1310 detects a comparison between the position data stored in present position register 1308 and the position data then read out from position data store 1306, the particular addressed location from which this position data has been read represents the display register which displays that position data. 
     Read-out address generator 1312 also is coupled to &#34;IN&#34; assignment table 1302 and to &#34;OUT&#34; assignment table 1304. A video, audio-1 or audio-2 control signal, which may be derived from the locations stored in these tables, is read out from one of these assignment tables if the address produced by read-out address generator 1312 represents a display register represented by the character stored in the corresponding location in that assignment table, provided that comparator 1310 detects a comparison between the position data then read out from position data store 1306 and the position data supplied to present position register 1308. The outputs of the assignment tables are coupled to record control arrangement 1314, such that when a video, audio-1 or audio-2 control signal is read out, it effects the commencement or termination of the recording of the corresponding signals. 
     In operation, let it be assumed that the characters stored in the &#34;IN&#34; and &#34;OUT&#34; assignment tables 1302 and 1304 are as illustrated in FIG. 13. Thus, the edit-in points for the video, audio-1 and audio-2 signals are established by the record IN position data, the EVENT-1 (in) position data and the EVENT-2 (in) position data, respectively, this position data being stored in corresponding locations in position data store 1306. Similarly, the edit-out points for the audio-1, video and audio-2 signals correspond to the record OUT position data, the EVENT-1 (out) position data and the EVENT-2 (out) position data, respectively. In the foregoing, it is appreciated that the EVENT (in) position data represents the position data that is displayed in the corresponding EVENT register when establishing the split-in mode. Similarly, the EVENT (out) position data is the position data stored in the corresponding EVENT register when establishing the split-out mode. 
     At the beginning of the agenda-edit operation, the apparatus illustrated in FIG. 13 searches for the edit-in points. The position data supplied to present position register 1308 is derived from the recording tape while that tape is advanced; and the manner in which this position data may be supplied to present position register 1308 is described in copending applications Ser. Nos. 139,748 and 139,702, each filed Apr. 11, 1980. As each new position data is supplied to present position register 1308, read-out address generator 1312 sequentially reads out the position data stored in the respective locations in position data store 1306. Ultimately, the position data supplied to present position register 1308 will be equal to the position data displayed in record IN register 80. Thus, when read-out address generator 1312 sequentially reads out the position data from the respective locations in the position data store, comparator 1310 will detect when the record IN position data is read out. This record IN position data now will be equal to the present position of the recording tape, as represented by the position data in present position register 1308. Comparator 1310 thus will enable &#34;IN&#34; assignment table 1302 to have a control signal derived therefrom. It may be appreciated that the address generated by read-out generator 1312 represents the location in the &#34;IN&#34; assignment table which corresponds to the record IN character. Thus, the control signal corresponding to this location in &#34;IN&#34; assignment table 1302 is derived therefrom. It is appreciated that, in the example illustrated herein, this control signal represents the video control signal. Consequently, record control arrangement 1314 is controlled by this video control signal to initiate the transfer, or re-recording of the video signals from the playback tape to the recording tape once the recording tape reaches the edit-in location corresponding to the record IN position data. 
     As the tapes continue to advance, the relative positions thereof, and especially that of the recording tape, are represented by the position data supplied to present position register 1308. As before, in response to each new position data supplied to the present position register, read-out address generator 1312 sequentially reads out the position data stored in the respective locations of position data store 1306. The recording tape ultimately reaches the edit-in point corresponding to the EVENT-1 (in) position data stored in position data store 1306. At that time, read-out address generator 1312 sequentially reads out the position data stored in the position data store, and when the EVENT-1 (in) position data is read out therefrom, comparator 1310 detects a comparison between the present position of the recording tape and this position data. Consequently, &#34;IN&#34; assignment table 1302 is enabled to derive a control signal. The address generated by read-out address generator 1312, which resulted in this comparison, corresponds to the EVENT-1 character which is stored in the A-1 location in the &#34;IN&#34; assignment table. The audio-1 control signal thus is derived from the &#34;IN&#34; assignment table. This audio-1 control signal is supplied to record control arrangement 1314 to initiate the transfer, or re-recording of the audio-1 signals on the recording tape. Thus, when the recording tape reaches the the edit-in point corresponding to the EVENT-1 (in) position data, the audio-1 signals are transferred. 
     An operation similar to aforedescribed operation is carried out to detect when the recording tape reaches the position corresponding to the EVENT-2 (in) position data, whereupon the audio-2 control signal is derived from &#34;IN&#34; assignment table 1302 to control record control arrangement 1314 to initiate the transfer, or re-recording, of the audio-2 signals. 
     The video, audio-1 and audio-2 signals now are re-recorded on the recording tape until their respective edit-out points are reached. At each pre-selected edit-out point, as determined by the assigned edit-out points stored in &#34;OUT&#34; assignment table 1304, the transfer, or re-recording of the video, audio-1 or audio-2 signals associated with those points terminates. Hence, as the recording tape advances, the position data supplied to present position register 1308 is updated, and read-out address generator 1312 reads out the position data stored in the respective locations in position data store 1306. Comparator 1310 compares each read out position data with the position data stored in present position register 1308. 
     Ultimately, the recording tape reaches the edit-out location corresponding to the position data displayed in EVENT-1 register 118. When this EVENT-1 (out) position data is read out from position data store 1306 by read-out address generator 1312, comparator 1310 detects a comparison between this read out position data and the present position data stored in present position register 1308. Consequently, comparator 1310 enables &#34;OUT&#34; assignment table 1304 to have one of the control signals derived therefrom. It is seen that, when comparator 1310 detects a comparison, the address generated by read out address generator 1312 corresponds to the EVENT-1 (out) character, which identifies the particular location in position data store 1306 from which the EVENT-1 (out) position data is read. THe comparator also enables &#34;OUT&#34; assignment table 1304 to derive the control signal corresponding to the location therein in which the EVENT-1 (out) character is stored. From FIG. 13, it is seen that this control signal is the video control signal. Hence, record control arrangement 1314 is controlled by this control signal to terminate the recording of the video signals on the recording tape. Therefore, the EVENT-1 (out) position data represents the edit-out point for the video signals. 
     The recording tape continues to advance, resulting in updating the position data supplied therefrom to present position register 1308. With each update in this position data, read-out address generator 1312 sequentially reads out the position data stored in the respective locations in position data store 1306. Then, when the recording tape reaches the position corresponding to the EVENT-2 (out) position data, comparator 1310 detects a comparison when the read-out address generator addresses the EVENT-2 (out) location of position data store 1306. At the same time, read-out address generator 1312 addresses the location in &#34;OUT&#34; assignment table 1304 wherein the EVENT-2 (out) character is stored. The comparison detected by comparator 1310 enables the audio-2 control signal to be derived from this location in the &#34;OUT&#34; assignment table, and to be supplied to record control arrangement 1314. In response to this control signal, further recording of the audio-2 signals onto the recording tape is terminated. 
     The foregoing operation is repeated when the recording tape is advanced to the edit-out location corresponding to the record OUT position data. That is, when the recording tape reaches this point, comparator 1310 enables control signals to be derived from &#34;OUT&#34; assignment table 1304. Read-out address generator 1312 now addresses the record OUT character in this &#34;OUT&#34; assignment table, thereby deriving the A-1 control signal. 
     From the foregoing, it is appreciated that, as read-out address generator 1312 generates sequential addresses for reading out the respective position data stored in the corresponding locations in position data store 1306, the corresponding characters in the &#34;IN&#34; and &#34;OUT&#34; assignment table also are addressed. When comparator 1310 detects a comparison between the position data which then is read out from the position data store and the position data which is stored in present position register 1308, the control signal corresponding to the location in the &#34;IN&#34; or &#34;OUT&#34; assignment table in which the addressed character is stored is derived. This comparison is detected only when read-out address generator 1312 generates an appropriate address which, of course, selects only one location in the &#34;IN&#34; and &#34;OUT&#34; assignment tables. Thus, only one control signal is derived from these assignment tables, depending upon the comparison which is detected by comparator 1310. If that control signal is derived from the &#34;IN&#34; assignment table, record control arrangement 1314 is controlled to commence a transfer or re-record operation of the corresponding signals. However, if the control signal is derived from the &#34;OUT&#34; assignment table, record control arrangement 1314 is controlled to terminate the transfer, or re-record operation for the corresponding signals. 
     It may be appreciated that, rather than control record control arrangement 1314, the control signals derived from the &#34;IN&#34; and &#34;OUT&#34; assignment tables may effect a similar control over a preview control arrangement. 
     FIG. 13 is intended to be merely a representative functional block diagram illustrating how the agenda-edit operation is carried out. The actual apparatus which is used, and the specific programmed routine which may be provided to carry out the agenda-edit operation may be modified, as desired. It is sufficient merely to detect when the recording tape is advanced to a selected edit-in or edit-out point, and then to control the appropriate edit operation once that point has been reached. For example, rather than read out all of the position data stored in the respective locations in position data store 1306, comparator 1310 can be supplied with the position data associated with the respective register selector characters which are stored in corresponding locations in the &#34;IN&#34; and &#34;OUT&#34; assignment tables, such that when the recording tape reaches one of these positions, the selected edit-in or edit-out operation is carried out. Furthermore, the assignment tables may store the position data displayed by the particular display register which is identified by the illustrated register selector characters, thus obviating position data store 1306. Still further, the split-in and split-out points may be derived by the operator from the playback tapes and stored in the &#34;IN&#34; and &#34;OUT&#34; assignment tables as corresponding points on the recording tape. It is recognized that various other changes and modifications to the functional arrangement shown in FIG. 13 may be made within the scope of the present invention. 
     CPU Control of Error Detection 
     The flow chart shown in FIGS. 14A-14D represents the programmed routine carried out by the CPU in order to detect the presence of an error condition and, moreover, to transmit indicator data words to console 10 whereby the operator is apprised of the probable cause and location of the detected error. That portion of the CPU memory which is shown in FIG. 13 may be used in conjunction with this error detection routine. 
     Turning now specifically to FIG. 14A, the CPU determines whether a character transmitted by the apparatus of FIG. 3 represents the operation of a control switch. As described above, PREVIEW switch 174 and RECORD switch 170 are control switches. Other switches provided on console 10 also may be recognized by the CPU as control switches; although for the purpose of the present discussion, the PREVIEW and RECORD switches are recognized as those control switches which initiate a preview or actual edit operation. In the absence of detecting a control switch character, the CPU returns to its START condition, awaiting the arrival of such a character. 
     When the control switch character is received and recognized, a counter, which may be similar to the counter described above with respect to FIGS. 12A-12C, has its count set to 0 (i=0). As before, the count of 0 is used to designate the V selector switch, the count of 1 is used to designate the A-1 selector switch and the count of 2 is used to designate the A-2 selector switch. Depending upon the particular count i of the counter, the CPU examines the corresponding selector switch to determine if it has been assigned with an edit-in or edit-out point. This determination may be made by sensing whether a register character is stored in the corresponding location in the &#34;IN&#34; or &#34;OUT&#34; assignment tables. It is recalled that, in establishing the parameters for split-in and split-out edit modes, individual edit-in and edit-out points may be assigned to the respective V, A-1 and A-2 switches. If a simple edit operation is to be carried out, then either the play IN or record IN character may be stored in each location of the &#34;IN&#34;  assignment table. Similarly, either the play OUT or record OUT character may be stored in each location of the &#34;OUT&#34; assignment table. This, of course, means that the position data displayed in IN register 50 or IN register 80 represents the assigned edit-in point for all of the video and audio signals. Also, the position data displayed in OUT register 54 or OUT register 84 represents the edit-out point for all these signals. 
     If the signal associated with the signal selector switch designated by the count of the counter has not been assigned with an edit point, the count of that counter is incremented by 1 (i+1), and if this count has not yet reached 3,  the CPU senses whether the signal selector switch designated by the new count has been assigned with an edit-in or edit-out point. If no assignment has been made, the count of the counter is incremented again, and the signal selector switch designated by this incremented count is examined. In the absence of an assignment of an edit-in or edit-out point to this signal selector switch, the count is incremented once again, such that it now is equal to a count of 3 (i=3). The programmed routine then inquires whether an &#34;OK&#34; flag has been set. As will be explained this &#34;OK&#34; flag is set only if one of the signal selector switches has been assigned with the play IN or record IN character. In the absence of the setting of this &#34;OK&#34; flag, that is, in the absence of assigning the edit-in point to any of the video or audio signals, the lamps associated with all of the V, A-1 and A-2 switches are flashed. Furthermore, the lamp associated with SPLIT OUT switch 136 is not flashed, the CLEAR lamp is flashed indicating an error condition, and the programmed routine advances to an ERROR RETURN condition. In this ERROR RETURN condition, the lamp associated with the CLEAR switch is energized and, moreover, the operation selected by the control switch is inhibited. The operator thus is apprised of the particular error condition that none of the video and audio signals have been assigned with an edit-in point. 
     If the CPU determines that the signal associated with the signal selector switch designated by the count of the counter has been assigned with an edit-in point, inquiry is made as to whether this edit-in point is represented by the position data in the play IN or record IN register. It is recalled that, in a simple edit mode, the position data displayed in one of these registers represents the edit-in point for all of the video and audio signals. For a proper split-in mode, the position data in one of the play IN or record IN registers represents the edit-in point for at least one of these video and audio signals. 
     Assuming that the signal associated with the signal selector switch designated by the count of the counter has been assigned with the edit-in point represented by the play IN or record IN register, inquiry then is made as to whether this assigned register is blanked. As described in copending application Ser. No. 139,444, filed Apr. 11, 1980, a particular display register may be blanked if the CLEAR switch is operated as a source switch and the appropriate register selector switch is operated as the destination switch. If the play IN or record IN display register is blanked, then the present position of the playback or recording tape, as represented by the position data then present in tape timer register 58 or 88 is assigned as the edit-in point. The &#34;OK&#34; flag then is set. As shown in FIG. 14A, if the assigned play IN or record IN register is not blanked, then the position data in this assigned register represents the edit-in point, and the &#34;OK&#34; flag is set. 
     After the &#34;OK&#34; flag is set, the count of the counter is incremented by 1, and so long as this incremented count is not equal to 3, the foregoing operation is repeated. That is, the signal associated with the signal selector switch now designated by this incremented count is examined to determine if it has been assigned with an edit-in point. If not, the count of the counter is incremented again, and the foregoing operation is repeated in the manner described above. 
     If the CPU senses that the signal associated with the signal selector switch then designated by the count of the counter has been assigned with an edit-in point, but that this assignment is not represented by the position data in the play IN or record IN register, inquiry is made as to whether this assignment is represented by the position data in the EVENT-1 (in) register. It is recalled that the position data in an EVENT register may be derived either from the playback or recording tape. The CPU memory is provided with a suitable direction table in which appropriate direction codes are stored so as to represent whether the position data in the EVENT register has been derived from the playback or recording tape. As shown in FIG. 14A, if it is determined that the signal associated with the signal selector switch then designated by the character has been assigned with an edit-in point represented by the position data in the EVENT-1 (in) register, the direction code associated with that position data is retrieved. If this direction code is not present, for example, if the data in the EVENT-1 register has been derived from keyboard 150 and scratchpad register 142, then it is not proper to assign this data as an edit-in point. Accordingly, the LED direction indicators adjacent the EVENT-1 register are flashed, the lamp associated with the SPLIT OUT switch is not flashed, the CLEAR lamp is flashed, and the CPU advances to its ERROR RETURN condition. It is recognized that, in the absence of a direction code associated with the data in the EVENT-1 (in) register, neither the playback (P) nor the record (R) LED indicators adjacent the EVENT-1 register would have been energized. 
     If, however, it is ascertained that the data in the EVENT-1 (in) register has a direction code associated therewith, thus indicating whether the data in this register has been derived from the playback or recording tape, the programmed routine inquires as to whether the EVENT-1 register is blanked. If the answer to this inquiry is in the affirmative, thus representing that the signal associated with the signal selector switch then designated by the count of the counter has been assigned with a blanked edit-in point, the lamp associated with the EVENT-1 selector switch is flashed, the lamp associated with the SPLIT OUT switch is not flashed, the CLEAR lamp is flashed and the CPU advances to its ERROR RETURN condition. 
     From the foregoing, it is seen that the operator is apprised of the error condition wherein one (or more) of the video and audio signals has been assigned with an edit-in point represented by data in the EVENT-1 (in) register, but that data may not be position data, (i.e. it has not been derived from the playback or recording tape). The operator also is apprised of the error condition wherein one or more of the video and audio signals has been assigned with a blanked edit-in point. The source of this error condition, that is, the contents of the EVENT-1 register, is indicated by the flashing LED direction indicators or by the flashing EVENT-1 lamp. 
     If it has been determined that the signal associated with the signal selector switch then designated by the count of the counter has been assigned with a proper edit-in point represented by the position data in the EVENT-1 (in) register, this position data is converted so as to represent a corresponding edit-in point along the recording tape. If the EVENT-1 (in) position data has been derived from the playback tape, a difference signal is produced by subtracting the play IN position data from the EVENT-1 (in) position data. This difference signal Δ then is added to the record IN position data, resulting in a corresponding EVENT R  -1 (in) position data which represents the location along the recording tape that would be reached simultaneously with the EVENT P  -1 (in), representing an edit-in point on the playback tape. This EVENT R  -1 (in) position data is used subsequently (as will be described below); and therefore, is stored for such further use in a suitable location in the CPU memory. 
     If it has been determined that the signal associated with the signal selector switch then designated by the count of the counter has not been assigned with an edit-in point represented by the position data in the EVENT-1 register, it is assumed that this signal is assigned with an edit-in point represented by the position data in the EVENT-2 register. The direction code associated with this position data is retrieved, whereby it can be ascertained whether this edit-in point had been derived from the playback tape or from the recording tape. If such direction code is absent, then, as described previously with respect to the data in the EVENT-1 register, the direction indicator LED&#39;s adjacent the EVENT-2 register, that is, record (R) and playback (P) indicators 130 and 132 are flashed, the SPLIT OUT indicator (i.e. the indicator lamp associated with SPLIT OUT switch 136) is not flashed, and the CPU proceeds to its ERROR RETURN. The CLEAR indicator (i.e. the indicator lamp associated with CLEAR switch 162) is flashed to apprise the operator of this error condition. 
     However, if the direction code associated with the position data in the EVENT-2 register is present, inquiry is made as to whether this register is blanked. If so, that is, if the signal associated with the signal selector switch then designated by the count of the counter has been assigned with a blank edit-in point, this error condition is indicated by flashing the EVENT-2 indicator (i.e. the indicator lamp associated with EVENT-2 switch 128), flashing the CLEAR lamp and then proceeding to the ERROR RETURN condition. But, if the EVENT-2 register is not blanked, then the position data displayed therein is converted to a corresponding edit-in point along the recording tape. 
     If the direction code represents, for example, that the position data in the EVENT-2 register represents an edit-in point along the playback tape, the programmed routine converts this position data into a representation of the corresponding edit-in point along the recording tape. This is achieved by subtracting the position data in the play IN register (also referred to as the play IN edit point) from the position data in the EVENT-2 (in) register (also referred to as the EVENT-2 (in) edit point) to produce the difference signal Δ. This difference signal then is added to the position data in the record IN register (also referred to as the record IN edit point), thereby resulting in EVENT R  -2 (in) position data which represents a corresponding edit-in point along the recording tape. This EVENT R  -2 (in) position data is used subsequently, as will be described below; and is stored in an appropriate location in the CPU memory awaiting such use. 
     Although not specifically described herein, it should be appreciated that, although not necessary, a similar conversion operation is carried out even if the direction code associated with the EVENT-1 or EVENT-2 position data represents that such position data has been derived from the recording tape. Of course, in that event, it is recognized that the EVENT-1 or EVENT-2 position data already represents a respective edit-in point along the recording tape and, therefore, exists in the form of EVENT R  -1 (in) or EVENT R  -2 (in) position data. 
     After the EVENT-1 or EVENT-2 position data has been suitably converted to represent corresponding edit-in points along the recording tape, the count of the counter is incremented by 1 (i+1) and, if the count does not yet equal 3, the foregoing process, or loop, is repeated. Once this count is equal to 3, inquiry is made as to whether the &#34;OK&#34; flag has been set. It is recalled that this flag is set only if at least one of the video and audio signals has been assigned with the play IN or record IN edit point. If not, the error indication described above is provided. 
     Let it be assumed that the &#34;OK&#34; flag has been set. The programmed routine then proceeds to the flow chart shown in FIG. 14B. 
     The flow chart of FIG. 14B is substantially similar to that of FIG. 14A, and is intended to determine which, if any, of the video and audio signals have been assigned with edit-out points. Initially, a counter, which may be similar to, or the same as the counter described above with respect to FIG. 14A, has its count set to 0 (i=0). Next, inquiry is made as to whether the signal associated with the signal selector switch now designated by the count of this counter has been assigned with an edit-out point. It is recalled that all of the video and audio signals may be assigned with the very same edit-out point in a simple edit mode or, alternatively, these signals may be assigned with separate, individual edit-out points in accordance with a split-out mode. 
     If the signal associated with the signal selector switch designated by the count of the counter has not been assigned with an edit-out point, which may be ascertained by detecting whether the corresponding location in the &#34;OUT&#34; assignment table has a register character stored therein, inquiry next is made as to whether this signal has been assigned with an edit-in point. If the answer to this latter inquiry is in the affirmative, that is, if a particular signal has been assigned with an edit-in point but not with an edit-out point, an indication of this error condition is provided. This error indication is produced by flashing the upper and lower lamps associated with this selector switch; flashing the CLEAR lamp, and then proceeding to the ERROR RETURN condition. However, if this signal has not been assigned with an edit-in point, the count of the counter is incremented by 1 (i+1), and if this count is not yet equal to 3, the foregoing process is repeated. 
     Thus, as before, the signal associated with the signal selector switch now designated by the count of the counter is checked to determine if it has been assigned with an edit-out point. If this signal has been so assigned, inquiry is made as to whether this same signal has been assigned with an edit-in point. If not, that is, if this signal has been assigned with an edit-out point but not with an edit-in point, an error indication of this error condition is provided. This error indication is produced by flashing the upper and lower indicator lamp associated with this signal selector switch; flashing the CLEAR lamp, and advancing to the ERROR RETURN condition. However, if it is ascertained that the signal associated with the signal selector switch then designated by the count of the counter has been assigned with both an edit-in and an edit-out point, inquiry is made as to whether this edit-out point is represented by the position data in the play OUT or record OUT register (referred to as the play OUT position data and the record OUT position data, respectively). This assignment may be determined by sensing whether the play OUT or record OUT character is stored in the &#34;OUT&#34; assignment table at the location corresponding to the signal selector switch then designated by the count of the counter. If such an assignment has been made, the &#34;OK&#34; flag is set. 
     Next, inquiry is made as to whether the split-out mode has been selected to assign separate, individual edit-out points. If so, the program ascertains whether the play OUT or record OUT register (depending) upon which has been assigned) is blanked. In the split-out mode, a blanked edit-out register is not permitted. Hence, if it is determined that the play OUT or record OUT register is blanked, an error indication is provided by flashing the play OUT or record OUT indicator, flashing the SPLIT OUT indicator and flashing the CLEAR lamp, and then advancing to the ERROR RETURN condition. But, if the inquiry as to whether the split-out mode has been selected is answered in the negative, then a common edit-out point is assigned to all of the video and audio signals in accordance with the selected play OUT or record OUT register. If the selected play OUT or record OUT register is blanked, this is not an error condition. However, the operator will have to manually select an appropriate edit-out point which, of course, will be assigned to the signal then designated by the counter. Following this inquiry of whether the selected register is blanked if the split-out mode has not been selected, the count of the counter is incremented by 1 (i+1); and if this count is not yet equal to 3, the foregoing operation, or loop, is repeated. If the &#34;OK&#34; flag had been set, thus representing that the signal associated with the signal selector switch then designated by the counter has been assigned with an edit-out point represented either in the play OUT or record OUT register, and if the split-out mode had been selected, and if this register is not blanked, inquiry is made as to whether the play OUT position data is greater than the play IN position data, or whether the record OUT position data is greater than the record IN position data, depending upon the source of the edit-out point. That is, if the signal which is, effectively, designated by the counter, is assigned with the play OUT edit point, inquiry is made as to whether this edit-out point follows the play IN edit point. Alternatively, if this signal is assigned with an edit-out point along the recording tape, then inquiry is made to determine whether this record OUT edit point follows the record IN point. If this inquiry is answered in the negative, thus representing an erroneous parameter selected for the edit-out point, the corresponding play OUT indicator (i.e. the indicator lamp associated with edit-out switch 56) or record OUT indicator (i.e. the indicator lamp associated with edit-out switch 86) is flashed. That is, if this signal is assigned with the edit-out point represented by the position data in the play OUT register, but it is determined that this edit-out point precedes or is equal to the edit-in point represented by the position data in the play IN register, the play OUT indicator is flashed. Alternatively, if this signal is assigned with the edit-out point represented by the position data in the record OUT register, and it is determined that this edit-out point precedes or is equal to the edit-in point represented by the position data in the record IN register, then the record OUT indicator is flashed, the SPLIT OUT indicator is flashed, the CLEAR lamp is flashed and the program then advances to the ERROR RETURN condition. However, if the selected edit-out point properly follows the edit-in point, then the count of the counter is incremented by 1 (i+1); and if this count is not yet equal to 3, inquiry is made as to whether the signal associated with the signal selector switch now designated by this incremented count has been assigned with an edit-out point. 
     If the signal identified by the count of the counter is assigned with an edit-out point, and if this signal also has been assigned with an edit-in point, and if it is determined that the assigned edit-out point is not displayed in the play OUT or record OUT registers, inquiry next is made as to whether this edit-out point is represented by the data in the EVENT-1 (out) register. This, of course, may be ascertained by sensing whether the EVENT-1 character is stored in the OUT assignment table at the location corresponding to this signal. If this inquiry is answered in the affirmative, then, as was described above with respect to the flow chart of FIG. 14A, the direction code for the position data in the EVENT-1 (out) register is retrieved. If this direction code is absent, that is, if it cannot be determined whether this data has been derived from either the playback or the recording tape, this error condition is indicated by flashing the LED direction indicators 122 and 124 adjacent EVENT-1 register 118, by flashing the SPLIT OUT indicator, by flashing the CLEAR lamp, and by advancing to the ERROR RETURN condition. 
     However, if the direction code is present, inquiry next is made as to whether this EVENT-1 (out) register is blanked. If it is, that is, if this signal now identified by the count of the counter has been assigned with a blanked edit-out point, this error condition is indicated by flashing the EVENT-1 indicator, by flashing the SPLIT OUT indicator, by flashing the CLEAR lamp and by advancing to the ERROR RETURN condition. 
     However, if this last inquiry is answered in the negative, then the EVENT-1 (out) position data is converted to represent the corresponding edit-out point along the recording tape. This conversion is obtained in the manner described above. Thus, if the EVENT-1 (out) position data is derived from the playback tape (as represented by the direction code associated therewith), the difference signal Δ is produced by subtracting the play IN position data (i.e. the position data in the play IN register) from this EVENT-1 (out) position data. Then, this difference signal Δ is added to the record IN position data (i.e. the position data in the record IN register), resulting in the EVENT R  -1 (out) position data. This EVENT R  -1 (out) position data is used in subsequent operations; and is stored at an appropriate location in the CPU memory for such use. 
     Of course, if the EVENT-1 (out) position data had been derived from the recording tape, the difference signal Δ is produced by subtracting the record IN position data from this EVENT-1 (out) position data. 
     After the EVENT R  -1 (out) position data is obtained, the count of the counter is incremented by 1 (i+1); and if this count is not yet equal to 3, the foregoing operations are repeated. 
     If it is determined that the signal then identified by the count of the counter has been assigned with an edit-out point, that this signal also is assigned with an edit-out point, that the assigned edit-out point is not represented by the play OUT or record OUT position data, or by the EVENT-1 (out) position data, then it is assumed that this edit-out point is represented by the EVENT-2 (out) position data. The direction code associated with this EVENT-2 (out) position data is retrieved so as to verify that this position data has been derived either from the playback tape or from the recording tape. However, if this direction code is absent, then the LED direction indicators 130 and 132 adjacent the EVENT-2 register are flashed, the SPLIT OUT indicator is flashed, the CLEAR lamp is flashed and the programmed routine advances to the ERROR RETURN condition. 
     But, if the direction code associated with the EVENT-2 (out) position data is present, inquiry is made as to whether the EVENT-2 (out) register is blanked. If so, that is, if the signal identified by the count then present in the counter is assigned with a blanked edit-out point, the EVENT-2 indicator is flashed, the SPLIT OUT indicator is flashed, the CLEAR lamp is flashed and the programmed routine advances to its ERROR RETURN condition. But, if the EVENT-2 (out) register is not blanked, then the EVENT-2 (out) position data is converted so as to represent a corresponding edit-out point along the recording tape. This conversion is carried out in substantially the same way as described above and, therefore, in the interest of brevity, further description thereof is not provided. It will be appreciated that the converted EVENT-2 (out) position data is referred to herein as the EVENT R  -2 (out) position data. 
     Following this conversion, the count of the counter is incremented by 1 (i+1); and if this count is not yet equal to 3, the foregoing operations are repeated. However, if i=3, then inquiry is made as to whether the &#34;OK&#34; flag had been set. It is recalled that this flag is set only if the play OUT or record OUT position data is assigned as an edit-out point. If this flag has not been set, then the upper and lower lamps associated with all of the V, A-1 and A-2 selector switches are flashed, the SPLIT OUT indicator is flashed, the CLEAR lamp is flashed and the programmed routine advances to its ERROR RETURN condition. 
     If the &#34;OK&#34; flag had been set, the CPU advances to the routine illustrated in the flow chart of FIG. 14C. It is appreciated that this flow chart is reached only if the play IN or record IN position data has been assigned as an edit-in point and the play OUT or record OUT position data has been assigned as an edit-out point. 
     Turning specifically to FIG. 14C, the programmed routine represented therein is intended to ascertain whether each of the EVENT-1 (in), EVENT-2 (in), EVENT-1 (out) and EVENT-2 (out) edit points, if assigned, properly lies between the edit-out point represented by the record IN position data and the edit-out point represented by the record OUT position data. These determinations are made on the basis of the converted EVENT R  position data. Accordingly, inquiry is made as to whether the EVENT R  -1 (in) position data has been assigned as an edit-in point. If so, this position data is compared with the record IN position data to ascertain if it is equal to or greater than the record IN position data. Inquiry also is made as to whether this EVENT R  -1 (in) position data is less than the record OUT position data. If either of these inquiries is answered in the negative, that is, if it is concluded that the edit-in point represented by the EVENT R  -1 (in) position data does not lie between the record IN and record OUT position data, then the EVENT-1 indicator is flashed, the CLEAR lamp is flashed, and the programmed routine advances to its ERROR RETURN condition. 
     However, if the EVENT R  -1 (in) position data has not been assigned as an edit-in point or, alternatively, if this position data represents a proper edit-in point, then similar inquiries are made with respect to the EVENT R  -2 (in) position data. If it is determined that the EVENT R  -2 (in) position data does not lie between the points represented by the record IN and record OUT position data, the EVENT-2 indicator is flashed, the CLEAR lamp is flashed and the programmed routine advances to its ERROR RETURN condition. 
     If the EVENT R  -2 (in) position data has not been assigned as an edit-in point, or, alternatively, if it has been assigned as a proper edit-in point, similar inquiries are made with respect to the EVENT R  -1 (out) position data. That is, inquiry is made as to whether this EVENT R  -1 (out) position data has been assigned as an edit-out point. If so, it is determined whether this edit-out point lies between the points represented by the record IN and record OUT position data. The EVENT-1 indicator is flashed if it is concluded that the EVENT R  -1 (out) position data represents an improper edit-out point. In addition, the SPLIT OUT indicator is flashed, the CLEAR lamp is flashed and the programmed routine advances to its ERROR RETURN condition. However, if the EVENT R  -1 (out) position data has not been assigned as an edit-out point, or if it has been assigned as a proper edit-out point, the foregoing inquiries are made with respect to the EVENT R  -2 (out) position data. If this EVENT R  -2 (out) position data is assigned as a proper edit-out point, or, alternatively, if this EVENT R  -2 (out) position data has not been assigned as an edit-out point, the programmed routine advances to the flow chart shown in FIG. 14D. But, if the EVENT R  -2 (out) position data is not a proper edit-out point, that is, if it does not lie between the points represented by the record IN and record OUT position data, the EVENT-2 indicator is flashed, the SPLIT OUT indicator is flashed, the CLEAR lamp is flashed and the routine advances to its ERROR RETURN condition. 
     Turning now to the flow chart illustrated in FIG. 14D, this represents the programmed routine which ascertains whether the position data in the EVENT-1 and EVENT-2 registers represent proper edit-in points when the editing apparatus is used with an external device that is actuated or triggered by RELAY switches 138 and 140 when the recording tape reaches the positions represented by the EVENT-1 (in) and EVENT-2 (in) position data. Accordingly, inquiry first is made as to whether RELAY 1 is energized or ON. This inquiry is answered in the affirmative if an external device is connected to the editor and is adapted to be actuated by RELAY 1. Next, inquiry is made as to whether the EVENT-1 register is blanked. If so, that is, if RELAY 1 is ON so as to represent that the external device is to be triggered at a location represented by blanked position data, the EVENT-1 indicator is flashed, the CLEAR lamp is flashed and the programmed routine advances to its ERROR RETURN condition. However, if this EVENT-1 register is not blank, inquiry is made to determine if the EVENT-1 (in) position data lies between the points represented by the record IN and record OUT position data. If the EVENT-1 (in) position data does not subsist between these points, the foregoing error indication is produced. 
     However, if it is determined that RELAY 1 is not ON, or if this RELAY is ON and the EVENT-1 register contains position data representing a proper edit-in point, then the aforementioned inquiries are repeated with respect to RELAY 2 and the EVENT-2 register. If RELAY 2 is ON, but the EVENT-2 register is blank or contains position data that represents an improper edit-in point, then the EVENT-2 indicator is flashed, the CLEAR lamp is flashed, and the programmed routine advances to its ERROR RETURN condition. However, if RELAY 2 is not ON, or, alternatively, if this RELAY is ON and the EVENT-2 register contains proper position data, the programmed routine advances to its NORMAL RETURN. Although not described herein, it may be appreciated that the NORMAL RETURN enables the selected edit operation to be carried out. Thus, if PREVIEW switch 174 or RECORD switch 170 had been operated, thereby initiating the aforedescribed error detection routine, the preview or actual edit operation now is enabled to be carried out. 
     From the foregoing, it is appreciated that, in response to the operation of one or more control switches, an error detection routine is carried out to determine if the parameters which have been selected for the edit operation are correct. If an error condition is detected, an indication is provided so as to apprise the operator of the general source of that error. This facilitates error correction, whereby the operator may take corrective measures to enable the desired edit operation to be carried out. Furthermore, in addition to providing the error indication, the selected edit operation is inhibited until the error condition that results in that indication has been corrected. The operator then re-actuates the control switch, whereupon the error detection routine is carried out once again in order to verify that the detected error has been corrected and, furthermore, to detect the presence of any other error conditions. It is recognized that, in accordance with the error detection routine described herein, various error conditions are sensed in a predetermined hierarchy. As each so-called higher order error condition is detected and then corrected, the reactuation of a control switch by the operator results in re-initiating the error detection routine until, ultimately, no error conditions are detected. At that time, the selected edit operation is carried out. 
     While the present invention has been particularly shown and described with reference to a preferred embodiment, changes and modifications may be made to that embodiment without departing from the spirit and scope of this invention. For example, CPU 208 may be formed of discrete electronic circuitry, in the form of integrated circuits or otherwise, rather than as a programmed microprocessor or other computer device. Such a solid-state, or hard wired, version of the CPU nevertheless should perform the functions (or equivalents thereof) described above with respect to FIGS. 12A-12C and 14A-14D. As another example, the split-editing operation described herein can be carried out for various types of signals recorded on separate tracks, such as, for instance, multi-track audio signals that may be recorded on magnetic tape. An agenda-edit operation may be performed for such multi-track audio signals. Also, the selected edit-in and edit-out points may be derived from either or both of the recording tapes. For example, the position data displayed in the record IN display register may be utilized as one edit-in point, while the position data derived from the playback tape and displayed in the EVENT-1 register may be utilized as another edit-in point. Still further, various other indicators, as well as audible or speech indicators, may be used to provide error indications. 
     It is intended that the appended claims be interpreted as including all such changes and modifications.