Programmable multi-channel audio playback system for reel-to-reel tapes

A programmable multi-channel audio playback system includes a reel-to-reel tape having recorded thereon a plurality of segments of information on multiple channels, with the segments being separated by gaps containing either no information or coded information identifying the gaps, control apparatus for causing the tapes to move and for controlling such movement, reading apparatus for reading the information segments from the tape as the tape is moved, speaker apparatus for producing audio sounds from the information segments read by the reading apparatus, a microprocessor responsive to input signals for signalling the control apparatus to control movement of the tape and for signalling the speaker apparatus to control production of the audio sounds, and a manually operable keyboard for generating input signals which are supplied to the microprocessor. By keying certain information on the keyboard, the microprocessor is programmed to cause the reading from the tape of selected information segments and the production of audio sounds therefrom. The information segments may be read from the tape in any order desired and only selected information segments need be read.

This invention relates to a multi-track audio playback system adapted for 
use with a reel-to-reel tape and having manual controls by which a user 
may select for playback particular information segments stored on the 
tape. Commercially available multi-channel tape systems, such as are 
presently used in the home or installed in automobiles, play the musical 
numbers recorded on the tapes in the sequence in which the numbers are 
recorded unless the "change" or "select" button or knob is depressed. When 
such a button is depressed, the tape system moves from one channel to the 
next adjacent channel and commences to play back the musical selection 
located on the adjacent channel. Of course, when the tape system moves 
from one channel to another, it may commence playback of a selection in 
the middle, end, etc., of the selection. Some tape systems also provide a 
"fast forward" capability, but there is no way of knowing where the 
beginning and ending of a musical selection is--and so finding a 
particular desired musical number requires simple "trial and error" 
attempts using the "select" and "fast forward" buttons. 
A number of so-called automatic tape selection systems have been proposed 
including that described in U.S. Pat. No. 4,014,039. In this system, 
programs are recorded on tapes so that a "silent" portion is located 
between each program. A keyboard panel is provided for supplying a desired 
number to a down counter which then counts downwardly from that number 
each time a silent portion on the tape is encountered during the fast 
forward movement of the tape. After a certain number of such silent 
portions are counted so that the downcounter reaches zero, the tape drive 
is stopped or returned to its normal playback speed so that the next 
program on the tape will be played. Of course, each time a user desires to 
skip some of the programs, he must key in an appropriate number and then 
cause the tape to move in the fast forward mode. That is, user 
intervention is required for each program that the user desires to hear 
out of order. 
A unit on the market at present is the Sharp RT-3388. This unit can in some 
fashion locate specific segments on a single channel, but cannot relate 
locations of segments on one channel to those on other channels. 
A type of automated audio tape information system is also disclosed in U.S. 
Pat. No. 3,804,993. In this system, a plurality of message segments are 
recorded on a tape with each message segment being separated by so-called 
markers and address information. When a particular message segment is to 
be played back, appropriate address input information is supplied and the 
system locates and reproduces the desired message segment. After the 
segment is reproduced, the tape recorder is stopped to allow the operator 
to take one of several actions. Again, this system requires operator 
intervention for each message segment which is to be reproduced out of 
order. 
SUMMARY OF THE INVENTION 
It is an object of the invention to provide a multi-channel audio playback 
system for use with reel-to-reel tapes in which certain ones of a 
plurality of programs recorded on the tapes may be chosen for playback by 
the user and then such programs will be automatically played (and 
replayed) without further intervention by the user. 
It is another object of the invention to provide such a system in which, 
upon keying into the system certain information, the programs may be 
played back in any sequence desired by the user. 
It is an additional object of the invention to provide such a system in 
which conventional reel-to-reel tape cassettes may be utilized. 
It is also an object of the invention to provide such a system in which 
sequential searching for desired programs on multiple channel tapes is 
obviated. 
It is a further object of the invention to provide a relatively simple and 
inexpensive audio playback system which may be manually programmed to 
automatically play back only selected programs recorded on a reel-to-reel 
tape. 
The above and other objects of the invention are realized in one embodiment 
thereof which includes a two-channel reel-to-reel tape on which are 
serially recorded a plurality of information segments, with "silent" or 
coded gaps positioned between the segments. Also included is tape control 
and drive apparatus responsive to control signals for causing and 
controlling movement of the tape, reading apparatus for reading the 
information segments from the tape and for applying such information to an 
audio speaker system, a microprocessor for producing control signals for 
application to the tape drive and control apparatus and for signalling the 
speaker system to control audio reproduction of the information segments, 
and a keyboard device on which a user may manually key information 
identifying which information segments he desires to hear and the order in 
which he desires to hear the segments. The keyed information is received 
by the microprocessor which responds by producing control signals to 
indicate to the tape control and drive apparatus the manner in which the 
tape is to be moved to locate the selected information segments. Control 
signals are also produced by the microprocessor to indicate to the speaker 
system the times during which the speaker system is to reproduce the 
information applied to it by the reading apparatus. The information keyed 
on the keyboard is maintained in storage by the microprocessor to continue 
control of the operation of the system until new information is keyed. 
That is, the selected information segments are repeatedly reproduced until 
new information is keyed on the keyboard directing the microprocessor to 
cause the reproduction of different information segments. The 
microprocessor may also be "programmed" to reproduce the information in 
any sequence desired by the user. The invention may be used with either 
multiple or single read head audio systems.

DETAILED DESCRIPTION 
Referring to FIG. 1, there is shown diagrammatically a reel-to-reel tape 4 
having two parallel channels or tracks. This tape is the conventional 
cassette type used in commercial audio equipment, except for the table of 
contents (TOC) portion 8 which will be discussed momentarily. It should be 
understood that for the width of the tape 4 shown in FIG. 1, the tape 
would be much longer than shown; FIG. 1 is for illustration only. 
As already noted, there are two channels, identified as "CH. #1" (channel 
1) and "CH. #2" (channel 2), positioned in parallel on the tape 4. 
Recorded on each channel are one or more information segments or portions 
of information segments. For example, on channel 1, information segments 
1, 2 and 3 are recorded. The information segments are recorded (and 
numbered in FIG. 1) in a serial fashion from left to right for channel 1 
and from right to left for channel 2 so that as the tape is "played back", 
the information segments would be reproduced and broadcast in consecutive 
order in accordance with their serial position on the tape. Separating 
each information segment is a gap in the channel in which no information 
is recorded. The information segments generally are of different lengths, 
but this of course depends upon the amount of information recorded in the 
segments. 
The tape 4 of FIG. 1 includes six information segments and eight gaps, with 
the gaps being numbered in ascending order as they are encountered 
(regardless of which channel) moving from the left end of the tape to the 
right end. In a portion of channel 2 at the end thereof is recorded a 
table of contents (TOC) 8 which contains information as to the location of 
each of the information segments, i.e., what channel each information 
segment is located, and what gap precedes and succeeds each information 
segment. This information, which is shown in table form in FIG. 2, may be 
recorded as multi-frequency tones which can be read and decoded into 
numbers representing the desired information. 
As shown in FIG. 2, each of the recorded information segments is listed in 
the first column followed by a column showing the preceding gap number and 
then a column showing the succeeding gap number. The final column shows 
the channel on which each of the segments is located. 
FIG. 3 is another embodiment of a two-channel reel-to-reel tape which is 
different from the FIG. 1 embodiment in that the information segments are 
separated by segments of coded multifrequency tones. The tones are coded 
to identify the gap number relative to the left end of the tape. Providing 
such tones in the gaps increases the certainty of locating the gaps when 
searching for the information segments and also reduces the processing 
requirements for finding an information segment, as will be discussed in 
greater detail later. 
FIG. 4 is a block diagram arrangement of a multi-channel audio playback 
system which may be used with reel-to-reel tapes of the type shown in 
either FIG. 1 or FIG. 3. The system includes a microprocessor 50 which 
controls the operation of the other components of the system. Such control 
is effected by receipt of and transmission of signals over a data bus 54. 
Coupled to the data bus 54 is a random access memory 58 for use by the 
microprocessor for temporary storage of data and for storing the table of 
contents information shown in FIG. 2, and a read only memory 62 which 
contains programs for controlling system operation. The configuration of a 
microprocessor 50, random access memory 58, and read only memory 62 as 
shown is conventional. The microprocessor 50 could illustratively be a 
Zilog Z-80 made by Zilog Corporation. 
Also coupled to the data bus 54 is a read multiplexer unit 66 and a write 
register 70. The read multiplexer unit 66 receives information from a 
plurality of different units (to be discussed hereafter), and supplies 
such information in a multiplexed fashion to the data bus 54 for transfer 
to the microprocessor 50 or the random access memory 58. The units 
connected to the read multiplexer unit 66 include a manually operable 
keyboard 74, a tape tension detection switch 78, a microswitch 82, a tone 
detector 86 and a gap detector 90. Amplifiers 94 and 98 amplify signals 
received from a read head 102 for application respectively to the tone 
detector 86 and gap detector 90. The read head is a conventional monaural, 
single-channel read head which is maintained in continual contact with or 
close proximity to an endless tape 106. The detector switch 78 is 
maintained in constant contact with the tape for detecting when the tape 
becomes taut (indicating the end of the tape). When the tape is being 
played, it is not taut so that the switch 78 is not operated. The read 
head 102 is positionable by a channel change solenoid 126 to read 
information stored on either of the two channels included on the endless 
tape 106. These elements are conventional for a tape player system. 
The write register 70 receives information from the microprocessor 50 via 
the data bus 54 to control the operation of a play right solenoid 110, a 
play left solenoid 114, a rewind right solenoid 118, a rewind left 
solenoid 122, the channel change solenoid 126, and an audio enable circuit 
130. The write register could illustratively be a decoder for supplying a 
signal to a selected one of the solenoids or the audio enable circuit in 
response to data from the microprocessor. When the play right solenoid 110 
is signalled by the write register 70, it causes the tape 106 to move to 
the right at the normal play speed. When the write register 70 signals the 
play left solenoid 114, this solenoid causes the tape 106 to move to the 
left at the normal play speed. When the write register 70 signals the 
rewind right or rewind left solenoids 118 and 122, these solenoids cause 
the tape 106 to move at a faster than normal speed to the right and left 
respectively. When the write register signals the channel change solenoid 
126, the channel change solenoid, as indicated earlier, causes the read 
head 102 to change channels on the tape. Finally, the audio enable circuit 
130, when signalled by the write register 70, allows passage of signals 
from the read head 102 to an amplifier 134 which amplifies the signals and 
applies them to a speaker 138 which will reproduce the signals for 
listening by the user. The audio enable circuit 130 could illustratively 
be a transistor or similar triode control device. 
In operation, when a user desires to play a particular tape such as that 
depicted in FIG. 1, he inserts the tape into a conventional tape 
receptacle so that the tape is positioned adjacent the read head 102 and 
the switch 78. Such a tape would contain the table of contents section 
earlier described in connection with FIGS. 1 and 2. When the system is 
turned on, i.e., when power is supplied to the microprocessor 50, it 
applies a signal to the write register 70 to cause the write register to 
operate the channel change solenoid 126. In response, the channel change 
solenoid causes the read head to move to channel 2 (or stay on channel 2 
if it is already there). When the read head 102 is at channel 2, it is out 
of contact with the microswitch 82 and a signal indicating this is applied 
to the read multiplexer unit 66 which, in turn, applies the signal to the 
microprocessor 50 via the data bus 54. The microprocessor 50 then signals 
the write register 70 to activate the rewind left solenoid 122. The rewind 
left solenoid causes the tape 106 to move to the left until the end of the 
tape is detected by the tape tension detection switch 78. When this 
occurs, the switch 78 applies a signal to the read multiplexer unit 66 
which in turn applies it to the microprocessor 50. The microprocessor then 
applies a signal to the write register 70 to activate the play right 
solenoid 110. The play right solenoid, in turn, causes the tape 106 to 
move right in its normal play mode and the read head 102 reads the 
information stored in the table of contents segment on the tape which, as 
indicated earlier, consists of different combinations of tones. This 
information is applied by the read head 102 to the amplifier 94 which 
amplifies the signals for application to the tone detector 86. The tone 
detector 86 then produces a sequence of signals representing the detected 
tones for application to the read multiplexer unit 66. These signals are 
then applied to the data bus and stored in the random access memory 58. 
After reading out the table of contents from the tape, the read head 102 
encounters gap 2 on channel 2, and this is detected by the gap detector 90 
which accordingly signals the read multiplexer unit 66. The read 
multiplexer unit 66 applies this signal to the data bus 54 and to the 
microprocessor 50 which then signals the write register 70 to deactivate 
the play right solenoid 118. The movement of the tape is thus halted at 
gap 2 in channel 2. The system is now in condition for being "programmed" 
by the user to play the selected information segments. 
The user keys in on the keyboard 74 an indication of the information 
segments which he desires to have played back. The keyboard 74 could be a 
conventional push button type keyboard in which a different signal is 
applied to the read multiplexer unit 66 for each key depressed. Each of 
the keys on the keyboard would be used to identify a different one of the 
information segments on a tape so that when any key was pushed, a signal 
would be applied to the multiplexer 66 and then to the microprocessor 50 
to indicated that that information segment is to be played. 
Assume that a user has keyed in information indicating that he desires to 
play segments 1, 2, 5 and 6. These information segments may be played back 
in numerical sequence or in the sequence in which the keys representing 
the different information segments are depressed. If it is desired to play 
the segments in numerical sequence (i.e., 1, 2, 5 and 6), then the 
microprocessor 50 simply plays back each segment beginning with segment 1 
and at the end of playback of a segment, determines the channel and the 
number of gaps to count to reach the next segment. The information as to 
the number of gaps to count and the channel on which the segment is 
located can be computed from the table of contents which is already stored 
in random access memory 58. Thus, for the segments in question, the read 
head 102 would be changed to channel 1 and then would be rewound left 
until gap 1 were encountered. Then the tape would be moved right at the 
play speed to play segment 1 followed by segment 2. After that, the read 
head 102 would be positioned at gap 6 following segment 2. To reach 
segment 5, the tape would be rewound right to the end of the tape, the 
read head would be moved to channel 2, and the tape would be moved in the 
rewind left mode until gap 5 on the channel was encountered. Segment 5 
would then be read from the tape until gap 4 were reached. Segment 6, 
since it follows segment 5, would next be played back after which the read 
head would be positioned at gap 2 following segment 6 in channel 2. 
Since, upon programming the system to play a particular group of 
information segments, the system continues to play such segments until 
"reprogrammed", after segment 6 were read back, the system would next 
return to the beginning of segment 1. This would be done by changing the 
read head to channel 1 and rewinding left until gap 1 were encountered. 
After this occurred, the tape would be moved in the play right mode to 
play back segment 1, etc. 
If the segments are to be played back in the sequence in which the 
corresponding keys are depressed, then the microprocessor simply stores 
information identifying this sequence in the same fashion that it would 
search in numerical sequence. 
Exemplary circuitry for the keyboard 74, multiplexor 66, tone detector 86 
and gap detector 90 is disclosed in the aforecited application of which 
this is a continuation-in-part. It is apparent that various specific 
implementations of the units of FIG. 4 could be provided. 
For use with the tape represented in FIG. 3, the FIG. 4 system need not 
include the gap detector 90 and amplifier 98. This is because each gap is 
identified by coded multi-frequency tones. To locate a particular 
information segment on the FIG. 3 tape (assuming that the table of 
contents has been read by the microprocessor 50), the system simply 
switches to the channel on which the segment is located and then moves the 
tape in a rewind left mode, if the preceding gap number of the desired 
segment is less than the current gap location, or a rewind right mode, if 
the preceding gap number of the desired segment is greater than the 
current gap number. The tape is moved until the multi-frequency tone of 
the desired gap location is detected. Of course, if the desired gap 
location is the same as the current gap location, then no tape movement is 
necessary. After the desired gap is found, the system plays back the 
desired segment in the proper direction (right for channel 1 and left for 
channel 2) until the multi-frequency tone which follows the desired 
segment is encountered. Since the gaps are coded, counting of gaps is 
unnecessary and this expedites the finding of desired information 
segments. 
FIG. 5 shows an alternative arrangement of a reel-to-reel tape in which six 
information segments are recorded on two different channels or tracks. 
This recording arrangement is similar to that of FIG. 3 except that the 
multi-frequency tone segments separating the information segments are 
coded to identify the next following information segment, and no table of 
contents is included. Also, multi-frequency tone segments E represent the 
"end of the channel". This tape arrangement is designed for use with a 
multiple read-head playback system such as that shown in FIG. 6. 
Many of the components of the FIG. 6 system are the same as those of the 
FIG. 4 system with the following exceptions: an additional read head, 
amplifier, tone detector and audio enable circuit are provided in the FIG. 
6 arrangement, and no channel change solenoid is provided in this 
arrangement. Also, the gap detector has been eliminated. 
As with the FIG. 4 system a microprocessor 150 controls the operation of 
the other components of the system through receipt of the transmission of 
signals over a data bus 154, and pursuant to programs contained in a read 
only memory 162. A random access memory 158 is provided for the temporary 
storage of information by the microprocessor 150. The other components of 
the FIG. 6 system will be discussed when describing the operation of the 
system. 
When a tape 186 is placed in the receptacle of the system and the power is 
turned on, the microprocessor 150 signals a rewind left solenoid 214 via a 
write register 170 to rewind the tape 186 to gap 1 preceding segment 1. A 
channel 1 read head 182 would supply the gap 1 tones to a channel 1 tone 
detector 190 via an amplifier which would then supply a signal to the read 
multiplexer unit 166 and ultimately to the microprocessor 150 which would 
stop the rewind operation. 
The desired segments to be played back may now be selected by appropriate 
keying of a keyboard 174. The keyed information is supplied via the read 
multiplexer unit 166 to the microprocessor 150. In response, the 
microprocessor 150 signals the rewind right solenoid 210 to cause the tape 
to move to the right and as it is moving, both channels are monitored by 
the microprocessor 150 to find the multi-frequency tone segment which 
precedes the segment to be first played. If this tone segment is in 
channel 1, as soon as the tone segment is detected, the microprocessor 150 
signals the play right solenoid 202 to cause the tape to move so that the 
selected segment is played back. If the tone segment is in channel 2, then 
the microprocessor 150 signals to play left solenoid 206 to cause the tape 
to move to the left to play the selected segment. Reproduction of the 
audio information is carried out the same as described for FIG. 4, with 
the appropriate one of audio enable circuits 218 or 222 being enabled 
depending upon which channel contains the desired segment. Playback 
continues until a multi-frequency tone is encountered which is both 
greater than the number of the segment being played back and is detected 
on the same channel as the segment being played back. (It should be noted 
that the "E" segment at the end of each channel is greater than any number 
encountered.) Detection during playback of a tone which meets these 
conditions causes the microprocessor 150 to stop the tape 186 by 
signalling whichever one of the play solenoids has been activated. The 
value of the last detected tones on each channel is stored in random 
access memory for use as next described. 
To locate the next desired segment, the system determines whether the 
desired segment is toward the left or right end of the tape, as follows: 
1. If the desired segment is numerically less than the last tone detected 
on channel 1, then the desired segment will be found toward the left end 
of the tape. 
2. If the desired segment is numerically greater than the last tone 
detected on channel 2, then the desired segment will also be found toward 
the left end of the tape. 
3. If the desired segment is both greater than the last tone detected on 
channel 1, and less than the last tone detected on channel 2, then the 
desired segment will be found toward the right end of the tape. 
4. If the desired segment equals the last tone encountered on channel 1 or 
channel 2 and if the tape was moving toward the right when the tone was 
encountered, then the desired segment will be found toward the left end of 
the tape. If the desired segment equals the last tone encountered on 
channel 1 or channel 2 but the tape was moving to the left when the tone 
was encountered, then the desired segment will be found toward the right 
end of the tape. 
Based on the above determination, the system simply moves the tape to the 
left or right as necessary, constantly monitoring both channels until the 
desired segment is located; that segment is then played back, etc. 
It is to be understood that the above-described arrangements are only 
illustrative of the application of the principles of the present 
invention. Numerous modifications and alternative arrangements may be 
devised by those skilled in the art without departing from the spirit and 
scope of the present invention and the appended claims are intended to 
cover such modifications and arrangements.