Abstract:
A television tuning system with a circuit for preventing the loss of information during power outages is disclosed. A disable signal is generated in response to the interruption of a mains power supply. In response to the disable signal, a series of fixed signals are applied to at least one of the date and address terminals of a memory containing the information to be preserved. An appropriate signal for preventing the information stored in the memory from being changed during the period in which the disable signal is generated is also applied to the memory.

Description:
RELATED APPLICATION 
     This is a divisional of U.S. patent application Ser. No. 040,079, filed May 17, 1979 now U.S. Pat. No. 4,314,375, issued Feb. 2, 1982. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention is directed towards a television tuning system which includes a circuit for preventing the loss of information stored in a memory and used by the television tuning system during its operation during power outages. 
     Electronic tuning systems are well known in the art. Such systems normally include a memory which stores information concerning the operating parameters of the television such as the frequency of channels which are to be tuned to, desired volume, brightness and color settings, etc. The memory also often stores other information such as the time of day, etc. 
     It is important to preserve the foregoing information in the case of power outages. This can be done using a permanent external memory (a battery-supplied, low consumption CMOS memory or non-volatile MNOS memory). Nevertheless, it has been shown that part of the data in the memory may be lost during the transient state between the loss of power and the return of the power. 
     It is a primary object of the present invention to provide a circuit arrangement designed to prevent loss of part of the data in the memory during the transient state between the loss of power and the return of the power. 
     SUMMARY OF THE INVENTION 
     In order to achieve the foregoing and other objects of the invention which will be clear from the following description thereof, the present invention is directed towards an apparatus for use with a television receiver, the apparatus comprising: 
     a power circuit for converting a mains power supply voltage to a reduced voltage which is applied as a power signal to several components of said television receiver, said power circuit generating said reduced voltage shortly after said mains power supply voltage is applied thereto and maintaining said reduced voltage until shortly after said mains power supply voltage is removed therefrom; 
     a read/write memory for storing information relating to the operating parameters of said television receiver, said memory having data terminals, address terminals, and one or more control terminals for controlling operation of said memory; 
     a control circuit for controlling said operating parameters of said television receiver as a function of said information stored in said memory and as a function of data signals applied thereto, said control circuit changing the values of said information stored in said memory by applying control signals to said data and address terminals of said memory in response to specific data signal applied to said control circuit; 
     first means for generating a disable signal responsive to an interruption of said mains power supply voltage, said disable signal being generated before said reduced voltage is cut off in response to the removal of said mains power supply voltage from said power circuit, said disable signal continuing until after said reduced voltage is again generated by said power circuit in response to the reapplication of said mains power supply voltage to said power circuit; 
     second means responsive to said disable signal for supplying a series of fixed signals to at least one of said data and address terminals of said memory; and 
     third means responsive to said disable signal for applying to at least one of said control terminals of said memory an appropriate signal for preventing said information stored in said memory from being changed during the period in which said disable signal is generated. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will now be described, by way of example only, with reference to the accompanying drawings, in which: 
     FIG. 1 shows the block diagram of part of a television receiver according to the present invention; 
     FIGS. 2, 3 and 4 show block diagrams of elementary logic functions performed by the circuits on the device according to the present invention; 
     FIGS. 5 and 6 show a number of FIG. 1 circuits in greater detail; 
     FIG. 7 shows the block diagram of a perfected version of the circuit of FIG. 1--only the differing features are shown. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Number 1 in FIG. 1 indicates a receiving aerial connected to varicap-diode tuner 2 which generates a signal converted to intermediate frequency IF at its output. The tuner is the known type and consists essentially of a selective amplifier stage, a mixer circuit and local oscillator circuit. 
     One output on the local oscillator circuit is connected to a first frequency-divider circuit 3 which divides by a fixed number N1 and whose output is connected to the signal input of a second divider 4 which divides by a variable number N determined by 12-bit signal, which means it can divide by any number from 1 to 2 12 . 
     The output of divider 4 is connected to a first input of phase-frequency comparator circuit 5 to whose second input a reference signal generated by quartz generator 6 is applied via a third frequency-divider circuit 7. The output of comparator circuit 5 is connected to the tuner circuit varicap diode voltage control input via amplifier and filtering circuit 8. 
     Number 10 indicates a control unit consisting of a keyboard which, besides the control keys not shown, such as the on/off switch and volume, brightness, contrast and color adjustment controls, also contains 10 number keys marked 0 to 9 (or letter keys marked A, B, C, D, E, F, G, H, I, L) and 7 auxiliary keys marked +, -, T, C, OR, M, CT (or +, -, R1, R2, R3, R4, CT). 
     This control unit is connected to a first group of eight input-output terminals of processing unit or circuit 11 and to the address inputs of memory circuit 12. The said processing unit also has a second set of eight input-output terminals connected to the data input-output terminals of memory circuit 12 and the inputs of character generator circuit 16. This, in turn, is connected to display device 9 (including the kinescope on the set) while a third group of 16 terminals is connected to: 
     12 programming inputs of 12-bit divider 4; 
     2 band-switch inputs (U and BIII) of tuner 2; 
     1 control input of character generator circuit 16; 
     a first input of combiner circuit 14. 
     Memory circuit 12 has further control terminals connected to the output of combiner circuit 14 which receives a signal from circuit 11 at a second input and a signal from on-detector circuit 15 at a third. Circuit 15 receives a signal from the power mains to which the television set is connected and also has its output connected to a RESET input of circuit 11. 
     Memory 12 and the low-current-absorption CMOS combiner circuit 14 are connected to a local battery supply source 13. The circuit operates as follows: 
     Circuits 3, 4, 5 and 8, together with the varicap-diode-controlled local oscillator (VCO) in tuner 2, form a phase lock loop controlled by the reference signal generated by quartz generator 6 and divided by divider 7 according to the known technique. 
     The function of divider circuit 3 is to reduce the frequencies involved to more easily processable levels while programmable divider 4 enables locking to be affected for a number of local oscillator frequencies, that is, it acts as a frequency synthesizer circuit. 
     In fact, after selecting division number N for divider circuit 4, phase-frequency comparator 5 supplies circuit 2, via amplifier 8, with voltage for obtaining the following condition: ##EQU1## in which f2 is the oscillation frequency of the local oscillator circuit in tuner 2, f6 is the oscillation frequency of reference oscillator circuit 6, N 2 , N 1  and N are the division ratios of dividers 3, 6 and 4 respectively, while P=f6 N 1  /N 2  indicates the system pitch, that is, the amount by which local oscillator frequency varies alongside variations in number N. 
     The receiver must be capable of tuning into broadcasting stations of a given transmission standard, e.g. C.C.I.R./B-G, with channeling as agreed at the 1961 European Radio Broadcasting Conference in Stockholm, that is, broadcasting stations with one-step spacing between adjacent 7 MHz channels on the I and III (VHF) bands and 8 MHz channels on the IV and V (UHF) bands with a 5 MHz video signal band width. These broadcasting stations fall within television channels 2 and 69 (video carrier frequencies 48.25 and 855.25 MHz respectively) with 38.9 MHz intermediate frequency IF. This means the local oscillator on the tuner must be capable of generating frequencies ranging from 87.15 to 894.15 MHz. A 0.25 MHz pitch was selected which, according to equation 2 gives the following values for the two above mentioned channels: ##EQU2## By varying number N between these maximum and minimum values, any television channel on the VHF and UHF bands can be tuned into with a maximum error of 125 KHz. 
     Not all of this frequency range can be utilized so the tuner is provided with two band switch inputs U (UHF/VHF) and B (BIII/BI) to ensure only effective bands are covered. Divider 3 is a high-speed ECL type which divides by 64 (SP 8750). Divider 4 is a programmable TTL which can operate up to frequencies of about 15 MHz (3×SN74LS191). Circuits 5, 6 and 7 consist of an SP8760 integrated circuit with 250 KHz frequency quartz and N 2  =64 division ratio so that comparator circuit 5 operates at 3906.25 Hz frequency which corresponds to a quarter of line frequency. The function of amplifier and filter 8 is to adapt the output level of comparator 5 (max. 5 V) to the requirements of tuner 2 (max. 30 V) and provide the best possible filtering and lock speed conditions. 
     Circuit 11, which consists of a microprocessor unit, is designed to generate, among other things, N numbers and bandswitch signals for tuning into specific television broadcasting stations on the basis of data relative to the signals being tuned into supplied by the user from control keyboard 10. The said circuit 11 is also capable of supplying or receiving signals from memory 12 and sending signals to character generating circuit 16. 
     Number N is calculated using the following equation: 
     
         N=(K.F+C)·4+S                                     (3) 
    
     The operations shown are performed by means of a series of elementary operations by an arithmetical-logic unit (ALU) on the basis of instructions contained in a (ROM) program memory contained in the processing circuit 11 and performed, in this case, using an F8 microprocessor. Constant correction C and factor F depend on the band selected; K is the channel number according to the said standard and the S variable can be changed for performing fine tuning corrections. 
     If channel number K is changed, we only get the frequencies corresponding to standard channels with a pitch equal to F (8 MHz for UHF and 7 for VHF), whereas one-unit variation of S causes frequency shifts of 0.25 MHz. 
     With appropriate control from the keyboard, various modes are possible for tuning into a given broadcasting station partly using known methods. 
     Whenever any one of the keys is pressed, processing unit 11 sends an ISO-coded 48-character sequence to character generator 16 which is displayed on the television screen in a three 16-character line arrangement. 
     This sequence always includes a time indication (hours, minutes, seconds). The remainder consists partly of fixed data from the ROM program memory (e.g. &#34;CHANNEL&#34; and &#34;KEY&#34; shown in FIG. 1) and partly of variable data depending on the controls activated by the user and the situation resulting from them which is memorized in a memory buffer inside unit 11 (e.g. the letter T indicating operation mode in the top right-hand corner of FIG. 1; figures 21-01, also in FIG. 1 following the &#34;CHANNEL&#34; indication which show the channel number and tuning correction). 
     The time indication is corrected automatically each second even if no key is pressed in the meantime. 
     When one of the &#34;T&#34;, &#34;C&#34;, &#34;OR&#34; or &#34;M&#34; keys is pressed, the corresponding operation mode is set and memorized in the memory buffer of processing unit 11. At the same time, one or more question marks are entered into the buffer at appropriate points to guide the user to the next control operation. The content of the buffer is then transmitted, of course, to the character generator and displayed on the television screen. 
     A few examples will now be given to give a clearer idea of this point. 
     When key &#34;T&#34; is pressed, the display shows: 
     00:MM:SS T 
     KEY ? 
     In this way, the user is informed that he has selected mode &#34;T&#34; (memory selection) and that the device expects a number key to be pressed (that is, an emitter memory key number). N.B.: 00:MM:SS in the above example stands for the time indication (hours, minutes, seconds). 
     When key &#34;C&#34; is pressed, the display shows: 
     00:MM:SS C 
     CHANNEL ?? 
     In this way, the user is informed that he was selected mode &#34;C&#34; (direct selection) and that the device expects two number keys to be pressed (required channel number). If the number formulated by these two keys corresponds to a channel in the standard, the said number will be displayed in place of the two question marks beside the &#34;CHANNEL&#34; indication. If the channel number does not correspond to one in the standard, the display shows: 
     00:MM:SS C 
     CHANNEL ?? 
     88 
     In this way, the user is informed that the control set (channel 88 not covered by the C.C.I.R. standard) has not been performed and that the device is awaiting further instructions. When key &#34;OR&#34; is pressed (causing the generation of a time reset control signal which is applied to processing unit 11), the display shows: 
     ??:??:?? T 
     CHANNEL 21+01 
     KEY 0 OR 
     This tells the user that the television set is still set to mode &#34;T&#34;, that it is tuned to channel 21 with a tuning correction equivalent to one frequency shift over 250 KHz, memorized on key 0, and that the device expects six number keys to be pressed one after the other corresponding to the hours, minutes and seconds the clock is to be reset to. As the six keys are pressed, the corresponding number is displayed in place of the &#34;OR&#34; indication and pairs of numbers replace the &#34;??&#34; corresponding to the hours, minutes and seconds, provided the numbers are acceptable. 
     In fact, the device checks the set numbers and, if the hour number is over 23 or the number corresponding to the tens of the minutes or seconds over 5, the two numbers (hours, minutes or seconds) are rejected and the two question marks are left displayed to inform the user that the device is waiting for another pair of acceptable numbers to be set. After the operation has been performed, the clock starts counting from the time set by the user. 
     The device is so designed that, following a power cut, a series of zeros is displayed for the hours, minutes and seconds and the clock remains in this condition to inform the user that the power supply has temporarily been cut off. 
     When the &#34;M&#34; key is pressed, the display shows: 
     00:MM:SS T 
     CHANNEL 21+01 
     KEY #? M 
     This tells the user that the television is still set to &#34;T&#34; mode, that it is tuned to channel 21 with +01 tuning and that the set is waiting for a number key to be pressed to memorize the channel tuned into. If key &#34;0&#34; is pressed, for example, the display shown in FIG. 1 appears and the channel is associated with key &#34;0&#34; for memory selection. If key &#34;+&#34; is pressed, the display shows: 
     00:MM:SS T 
     CHANNEL 21+02 
     KEY 0 
     This tells the user that the television is still set to &#34;T&#34; mode and that excess tuning corrections are being made, that is, towards the audio carrier of the received video signal. Circuit 11 supplies the programmable divider circuit, with a suitable modified number N and this tuning condition is automatically associated in the memory with key &#34;0&#34;. Operation is similar when key &#34;-&#34; is pressed except for the direction of the tuning adjustment (towards the video). Once nominal tuning is obtained, the &#34;+&#34; sign and the following number are cancelled while, for more defective tuning conditions, the &#34;-&#34; sign appears followed by the number of displacements made. The system is so designed to limit maximum variations to the -16 to +15 range. Of course, the tuning correction can be made in the same way even with the set in the direct selection mode (mode &#34;C&#34;). 
     In this case though, the operation does not involve automatic memorization. For the channel and obtained tuning condition to be memorized, the &#34;M&#34; key must be pressed, followed by a number key. 
     When the &#34;CT&#34; (keyboard switch) key is pressed, the display shows: 
     00:MM:SS *T* 
     CHANNEL 21+01 
     KEY 0 
     This tells the user (&#34;*&#34; beside the mode indication) that the device is set to perform a further series of functions corresponding to the second indication on each key. Following this operation, the processing circuit 11 supplies character generator 16 with a switch signal to switch the color of the writing on the screen or the background color so as to make it even more clear to the user that the controls available from that time on correspond to second key indications (this applies, of course, to color television sets). 
     If one of the keys marked &#34;A&#34; to &#34;L&#34; is pressed, the display shows: 
     00:MM:SS *C* 
     CHANNEL A 
     This tells the user that the television is set to mode &#34;C&#34; but, in this case, channels can be selected directly according to the Italian standard by pressing a single key with indication of the received channel. 
     When one of keys R1, R2, R3 or R4 is pressed, the display shows, for example: 
     00:MM:SS *1* 
     CHANNEL 21+01 
     KEY 0 RA 
     This tells the user that the set is performing an automatic scanning operation, for example type 1, or is scanning all the channels in the memory. 
     Scanning progresses automatically every two seconds with indications in each case of the key number and associated channel. At the same time, processing circuit 11 generates the relative N numbers for receiving the channel. Scanning stops when any other key is pressed. If the &#34;+&#34; or &#34;-&#34; key is pressed, the device remains set for manual advance or reversing (every time the &#34;+&#34; key is pressed, the key number is increased and decreased every time the &#34;-&#34; key is pressed). If the &#34;CT&#34; key is pressed, the device switches back to the first keyboard and awaits further instructions, in particular, tuning correction or memorization controls. Similarly, if key R2 is pressed after selecting the second keyboard using the &#34;CT&#34; key, this starts a type 2 scanning operation of all the standard channels (one switch per second). This can be stopped in the same way as type 1 scanning. 
     If key R3 is pressed, this starts a continuous scanning operation of the frequency band in 1 MHz steps, that is, 4 fine tuning switches per second, to detect any transmitters operating over non-standard frequencies. The same type of scanning operation, though at reduced speed (one switch every two seconds), is started pressing key R4. 
     The &#34;KEY&#34; indication is not displayed during type 2, 3 and 4 scanning operations. 
     Display or omission of the fixed &#34;CHANNEL&#34; and &#34;KEY&#34; indications depends on whether the indication or blank sectors of the ROM memory are utilized. Circuit 11 also comprises a timer which, 15 seconds after the last key has been activated, supplies a switch signal (bit 6 port 1) to character generator 16 which reduces the display to one line and also halves the height of the characters (7 instead of 14 television lines) to reduce disturbance to the picture. This switch signal, of course, is not supplied during automatic scanning or clock adjustment. 
     To prevent memorized data being lost during a power outage provision is made for a battery-supplied outside RAM memory 12. Whenever a memorization operation is performed, processing unit 11 updates the information in the RAM memory. When power supply returns to normal, the same unit 11 calls up the data memorized in the RAM memory. 
     &#34;ON RESET&#34; circuit 15 and combiner circuit 14 protect the data contained in RAM memory 12 during transient states between power supply failure and restoration. 
     Operation of processing unit 11 is shown more clearly in the elementary logic function block diagrams in FIGS. 2, 3 and 4. 
     FIG. 2 shows operation mode and relative indication selection; 
     FIG. 3 shows updating of the data in outside RAM memory 12; 
     FIG. 4 shows data being called up from the outside RAM memory following restoration of the power supply. 
     Number 20 in FIG. 2 indicates a timer which sets a switch circuit, 22, with its output usually towards block 23 and supplies an RTI signal to block 21 which reads the controls set on the keyboard. Block 21, via switch 22, supplies a signal to block 23 which ascertains the presence of a new order. The &#34;NO&#34; output supplies the RTI signal which reactivates reading block 21 while the &#34;YES&#34; output activates block 24 which ascertains whether the key pressed was a mode key. The &#34;NO&#34; output of block 24 activates block 25 which examines the operation mode selected and, in turn, activates block 26 which, depending on the mode chosen, combines and supplies the indication sequence to the character generator for display. Block 26 then activates block 27 which examines the number keys pressed and activates block 28 which ascertains whether the corresponding order is feasible. 
     The &#34;NO&#34; output of the block 28 (control not feasible, e.g. the number does not correspond to a standard number channel) activates a following block 34 which inserts question marks at appropriate points in the buffer to inform the user that the control is not feasible and transmits them to character generator 16 (FIG. 1). Block 34 then supplies an RTI signal to block 21 which reads the keyboard once more awaiting further instructions. 
     The &#34;YES&#34; output of block 28 activates block 29 which sends the channel or key numbers to the buffer, usually the numbers of the order received, transmits the numbers to the character generator and, finally, activates block 30 which calculates number N according to equation (3) and sends this number to programmable divider 4 (FIG. 1) to obtain the required tuning. Finally, block 30 supplies the RTI signal to block 21. 
     The &#34;YES&#34; output of block 24 activates block 36 which inserts the indications and question marks in the buffer and transmits them to the character generator (as described already). Block 36 then supplies block 21 with the RTI signal. After a set length of time (about 4 milliseconds), depending on circuit 20, switch 22 positions itself with its output towards count circuit 31 which, after a set number of pulses (about 250) per second, supplies a signal to block 32 which updates the clock numbers in the buffer and activates block 33 which sends the data contained in the buffer to the character generator and then supplies an RTI signal to block 21. Number 40 in FIG. 3 indicates a block for ascertaining whether the operation selected involves memorization. The &#34;NO&#34; output supplies a signal which activates block 25 (FIG. 2) while the &#34;YES&#34; output activates in turn: 
     block 41, which examines the number of the key pressed; 
     block 42, which memorizes the channel number and tuning in the registers corresponding to the said key; 
     block 43, which supplies an enabling signal (C.E.) and a first address for the outside memory circuit 12; 
     block 44, which supplies the channel number data and a memorizing pulse (WRITE) to the same circuit 12; 
     block 45, which supplies the new address; 
     block 46, which supplies the tuning data and memorizing pulse to memory 12. 
     Number 50 in FIG. 4 indicates a block which, following an &#34;ON RESET&#34; signal from circuit 15 in FIG. 1, supplies an output enabling (O.E.) signal to memory 12 as well as a signal for activating in turn: 
     block 51, which supplies the address to memory 12; 
     block 52, which reads the data from memory 12 and loads it into the registers in unit 11 of FIG. 1; 
     block 53, which calculates the new address; 
     block 54, which ascertains whether all the cells in memory 12 have been read. The &#34;NO&#34; output of block 54 supplies a signal for activating block 51 once more. The &#34;YES&#34; output activates block 55 which sets to mode &#34;T&#34; (memory selection) and key &#34;0&#34; and supplies an activation signal to block 25 of FIG. 2. 
     For further information concerning operation of the device, refer to Italian patent application No. 69950-A/77, noted above, which describes a device partly similar to the present one. In the actual device, a Fairchild F8 microprocessor unit was chosen for processing unit 11 which comprises a 3850 C.P.U., 3861 P.I.O., 3853 S.M.I. and two PROM F93448 memories. Each of the said two PROM memories comprises a connection matrix with a 512×8 format, input and address decoding circuits and output buffer circuits. 
     Each connection may be open or closed and represents permanent elementary data (bit) 1 or 0 respectively. Each group of 8 connections, addressed by one of the 512 address input combinations, represents an elementary 8-bit instruction or word (byte). By applying all the possible address combinations at the input, all the data contained in the ROM can be obtained at the output in word form. 
     These connections are described in the following tables for the circuit. The left-hand columns show the addresses, using hexadecimal notation, and the right-hand ones the connections of the corresponding memory cell. Number 1 refers to an open connection with logic 1 at the output while 0 refers to a closed connection. 
     As each memory cell consists of 8 connections, this means it can be represented with a combination of 8 binary figures. For the sake of simplicity, the hexadecimal system was used on the following tables, so that, for example, EA for base 16, which corresponds to 11101100 of base 2, indicates that the corresponding memory cell has connections 1, 2, 3, 5 and 6 open and the rest closed. 
     
                       TABLE 1______________________________________ADDRESS   CODE         ADDRESS   CODE______________________________________0000      70           000C      040001      B5           000D      6A0002      B1           000E      7A0003      B6           000F      5C0004      BE           0010      6D0005      BF           0011      5C0006      B4           0012      7F0007      65           0013      580008      6F           0014      180009      5E           0015      07000A      8F           0016      67000B      FE           0017      5C0018      66           0031      700019      5E           0032      BD001A      8F           0033      5B001B      FE           0034      B5001C      20           0035      90001D      10           0036      12001E      0B           0037      1B001F      24           0038      A50020      90           0039      EB0021      B5           003A      840022      A4           003B      FD0023      5C           003C      590024      0A           003D      210025      1F           003E      100026      25           003F      490027      28           0040      940028      94           0041      190029      F5           0042      EB002A      7C           0043      5B002B      06           0044      91002C      15           0045      F3002D      5A           0046      73002E      B1           0047      BE002F      72           0048      1A0030      BC           0049      67004A      4B           0063      03004B      21           0064      66004C      1F           0065      6B004D      59           0066      5C004E      6F           0067      69004F      25           0068      5C0050      09           0069      290051      81           006A      020052      1A           006B      060053      25           006C      470054      0F           006D      560055      81           006E      490056      32           006F      570057      29           0070      5E0058      02           0071      460059      03           0072      5D005A      1A           0073      E8005B      EB           0074      84005C      5B           0075      1D005D      21           0076      66005E      10           0077      6A005F      20           0078      000060      FA           0079      CC0061      94           007A      910062      02           007B      17007C      7F           0095      25007D      5C           0096      0D007E      6E           0097      84007F      03           0098      0A0080      5D           0099      810081      5C           009A      230082      67           009B      250083      5E           009C      0F0084      8F           009D      840085      FE           009E      400086      90           009F      290087      E2           00A0      010088      25           00A1      3B0089      0B           00A2      67008A      81           00A3      6C008B      51           00A4      03008C      06           00A5      5C008D      03           00A6      7D008E      5E           00A7      66008F      5D           00A8      6A0090      7F           00A9      060091      5E           00AA      550092      02           00AB      200093      67           00AC      100094      6F           00AD      5200AE      20           00C7      E400AF      D3           00C8      5C00B0      5C           00C9      6700B1      47           00CA      6C00B2      E8           00CB      4700B3      94           00CC      5C00B4      03           00CD      E600B5      57           00CE      8400B6      56           00CF      9A00B7      46           00D0      4700B8      15           00D1      1300B9      C7           00D2      2400BA      51           00D3      1000BB      90           00D4      0B00BC      1D           00D5      4D00BD      55           00D6      5100BE      03           00D7      4C00BF      5E           00D8      5200C0      8F           00D9      2900C1      FE           00DA      0100C2      66           00DB      8400C3      5E           00DC      9000C4      5C           00DD      4A00C5      6A           00DE      6600C6      20           00DF      4C00E0      E8           00F9      1300E1      84           00FA      B500E2      35           00FB      0500E3      67           00FC      2400E4      20           00FD      1000E5      DD           00FE      0B00E6      5C           00FF      7200E7      6B           0100      5900E8      4D           0101      4100E9      CE           0102      5D00EA      1F           0103      B400EB      84           0104      0100EC      2B           0105      EA00ED      20           0106      B500EE      F3           0107      EA00EF      5D           0108      B500F0      47           0109      1F00F1      5C           010A      B500F2      E8           010B      0500F3      84           010C      4200F4      31           010D      5C00F5      A1           010E      3900F6      EA           010F      9400F7      B1           0110      F300F8      4C           0111      70                  0112      B40113      B5           012C      520114      A1           012D      6B0115      EA           012E      4E0116      B1           012F      C80117      70           0130      810118      57           0131      550119      45           0132      6C011A      06           0133      70011B      03           0134      CC011C      67           0135      81011D      6F           0136      BC011E      5E           0137      70011F      5C           0138      570120      6C           0139      900121      4C           013A      4A0122      E8           013B      490123      94           013C      230124      60           013D      0E0125      90           013E      940126      5B           013F      1E0127      13           0140      200128      18           0141      E20129      24           0142      5E012A      16           0143      20012B      C2           0144      DF0145      5C           015E      E80146      6B           015F      840147      4C           0160      210148      C8           0161      460149      91           0162      25014A      04           0163      05014B      03           0164      91014C      5D           0165      0C014D      5C           0166      00014E      65           0167      24014F      68           0168      030150      4A           0169      040151      04           016A      240152      7F           016B      650153      5D           016C      0B0154      5C           016D      460155      6B           016E      5D0156      5D           016F      470157      5C           0170      5C0158      6E           0171      7F0159      5D           0172      57015A      5D           0173      68015B      90           0174      4D015C      25           0175      15015D      46           0176      CC0177      25           0190      530178      23           0191      410179      91           0192      05017A      D4           0193      25017B      90           0194      01017C      05           0195      81017D      7F           0196      E7017E      66           0197      25017F      5E           0198      790180      5C           0199      910181      29           019A      E30182      02           019B      F80183      06           019C      250184      67           019D      090185      6B           019E      910186      03           019F      DE0187      5E           01A0      700188      8F           01A1      CE0189      FE           01A2      91018A      66           01A3      04018B      5E           01A4      03018C      5D           01A5      5D018D      67           01A6      5E018E      70           01A7      66018F      50           01A8      4101A9      25           01C3      C901AA      69           01C4      5101AB      81           01C5      2501AC      0B           01C6      1401AD      F8           01C7      9101AE      2A           01C8      4A01AF      03           01C9      1301B0      E001B1      8E           01CA      C101B2      24           01CB      1301B3      02           01CC      C101B4      51           01CD      5901B5      16           01CE      0101B6      53           01CF      2501B7      41           01D0      6901B8      14           01D1      8101B9      5D           01D2      0701BA      13           01D3      0301BB      59           01D4      5D01BC      13           01D5      7901BD      13           01D6      8E01BE      C9           01D7      1601BF      59           01D8      5E01C0      41           01D9      4101C1      F8           01DA      2501C2      5E           01DB      0401DC      20           01EE      0001DD      45           01EF      3801DE      81           01F0      2901DF      05           01F1      0001E0      74           01F2      3701E1      50           01F3      2901E2      20           01F4      0001E3      AF           01F5      4801E4      C3           01F6      2901E5      90           01F7      0001E6      2A           01F8      A201E7      FF           01F9      2901E8      FF           01FA      0001E9      FF           01FB      C901EA      FF           01FC      2901EB      FF           01FD      0101EX      FF           01FE      8401ED      29           01FF      FF______________________________________ 
    
     
                       TABLE 2______________________________________ADDRESS    CODE        ADDRESS   CODE______________________________________0200       29          02ED      5D0201       02          02EE      250202       DD          02EF      050203       29          02F0      810204       03          02F1      1C0205       26          02F2      700206       29          02F3      5E0207       02          02F4      5C0208       7A          02F5      6C0209       FF          02F6      39020A       FF          02F7      94020B       FF          02F8      EF020C       FF          02F9      69020D       FF          02FA      20020E       FF          02FB      67020F       FF          02FC      DC0210       90          02FD      5E0211       11          02FE      140212       20          02FF      CC0213       20          0300      5D0214       C1          0301      250215       51          0302      010216       13          0303      810217       13          0304      090218       13          0305      4C0219       59          0306      25021A       41          0307      03021B       14          0308      81021C       12          0309      04021D       24          030A      70021E       08          030B      5E021F       50          030C      5D0220       20          030D      4C0221       52          030E      F80222       C9          030F      5C0223       51          0310      6F0224       40          0311      4C0225       19          0312      210226       13          0313      010227       13          0314      CB0228       50          0315      210229       70          0316      1F022A       C2          0317      25022B       81          0318      1C022C       04          0319      20022D       70          031A      F3022E       90          031B      91022F       07          031C      050230       25          031D      280231       20          031E      020232       81          031F      9C0233       03          0320      030234       20          0321      050235       20          0322      710236       52          0323      040237       41          0324      1B0238       14          0325      0C0239       12          0326      4B023A       12          0327      F8023B       C0          0328      06023C       50          0329      25023D       41          032A      09023E       13          032B      81023F       13          032C      620240       C2          032D      030241       59          032E      6C0242       40          032F      5C0243       19          0330      6F0244       18          0331      5E0245       B1          0332      200246       01          0333      E20247       25          0334      5D0248       70          0335      020249       84          0336      13024A       08          0337      18024B       25          0338      24024C       74          0339      16024D       84          033A      25024E       04          033B      FE024F       70          033C      910250       90          033D      080251       02          033E      020252       72          033F      550253       C9          0340      200254       18          0341      D10255       B0          0342      5C0256       01          0343      710257       51          0344      040258       67          0345      500259       68          0346      66025A       03          0347      6A025B       C2          0348      45025C       84          0349      24025D       1D          034A      F5025E       50          034B      5C025F       20          034C      250260       FB          034D      020261       5C          034E      840262       81          034F      110263       08          0350      910264       20          0351      280265       FD          0352      470266       5C          0353      C00267       40          0354      810268       18          0355      020269       1F          0356      79026A       50          0357      25026B       20          0358      09026C       67          0359      81026D       59          035A      02026E       70          035B      70026F       D9          035C      570270       30          035D      290271       94          035E      010272       FD          035F      F90273       69          0360      200274       59          0361      100275       14          0362      520276       5D          0363      700277       49          0364      C00278       F8          0365      910279       5C          0366      03027A       7F          0367      24027B       53          0368      66027C       A1          0369      D1027D       22          036A      25027E       40          036B      01027F       B1          036C      920280       28          036D      030281       02          036E      200282       9C          036F      790283       00          0370      250284       25          0371      790285       C9          0372      810286       91          0373      020287       12          0374      720288       84          0375      510289       04          0376      29028A       29          0377      01028B       01          0378      FC028C       ED          0379      40028D       45          037A      13028E       06          037B      13028F       70          037C      C20290       57          037D      810291       20          037E      052092       FD          037F      200293       54          0380      1C2094       03          0381      900295       67          0382      E00296       6F          0383      250297       5E          0384      1C0298       5C          0385      810299       29          0386      04029A       01          0387      70029B       F0          0388      90029C       2A          0389      D9029D       03          038A      52029E       D0          038B      41029F       20          038C      9002A0       80          038D      DD02A1       B4          038E      5702A2       65          038F      7702A3       68          0390      5602A4       74          0391      5C02A5       59          0392      2902A6       7C          0393      0102A7       50          0394      F602A8       16          03B0      DF02A9       B4          03B1      CE02AA       CA          03B2      EF02AB       B4          03B3      DF02AC       39          03B4      DF02AD       94          03B5      CA02AE       FA          03B6      ED02AF       0A          03B7      DF02B0       25          03B8      FC02B1       34          03B9      FE02B2       94          03BA      F102B3       0A          03BB      FE02B4       67          03BC      F302B5       70          03BD      FA02B6       CC          03BE      DF02B7       81          03BF      DF02B8       03          03C0      C702B9       7A          03C1      FE02BA       8E          03C2      DF02BB       66          03C3      EB02BC       6E          03C4      FE02BD       4C          03C5      EC02BE       24          03C6      EB02BF       30          03C7      F002C0       18          03C8      DF02C1       B4          03C9      DF02C2       CA          03CA      C702C3       B4          03CB      FE02C4       0A          03CC      DF02C5       1F          03CD      DF02C6       0B          03CE      DF02C7       30          03CF      DF02C8       94          03D0      DF02C9       F4          03D1      DF02CA       CA          03D2      DF02CB       84          03D3      DF02CC       07          03D4      FF02CD       7B          03D5      FF02CE       59          03D6      FF02CF       75          03D7      FF02D0       50          03D8      FF02D1       90          03D9      FF02D2       D6          03DA      FF02D3       B4          03DB      FF02D4       33          03DC      FF02D5       81          03DD      FF02D6       06          03DE      FF02D7       53          03DF      FF02D8       A1          03E0      0502D9       21          03E1      0702DA       BF          03E2      1402DB       B1          03E3      0002DC       1C          03E4      0102DD       34          03E5      0302DE       94          03E6      0502DF       41          03E7      0702E0       72          03E8      0702E1       59          03E9      0702E2       20          03EA      D102E3       FE          03EB      D202E4       54          03EC      D302E5       65          03ED      D402E6       6F          03EE      D502E7       20          03EF      D602E8       67          03F0      D702E9       DC          03F1      D802EA       5E          03F2      D902EB       14          03F3      DC02EC       CC______________________________________ 
    
     The above tables contain, in coded form, one possible sequence of elementary operations for performing, via the microprocessor system indicated, the functions shown in the block diagrams and foregoing description. 
     FIG. 5 shows a more detailed representation of the block diagram of character generator 16 in FIG. 1. 
     Number 60 in FIG. 5 indicates a character count circuit for supplying the addresses to character memory 61. This has a 48×6 format for containing the 48 characters transmitted periodically by processing unit 11. 
     The six INPUT/OUTPUT terminals of the said memory are connected to six output terminals of PORT 71 of processing unit 11. These are also connected to six inputs of character ROM 62. 
     This may be a Fairchild 3258 type, for memorizing 64 characters for each of which it supplies an image consisting of a 5×7 point matrix. Each character is separated vertically from the next by two lines of blanks. 
     A built-in counter, which receives a clock signal with horizontal scanning frequency FH from the television circuits and a reset signal R1 from circuit 60, scans the following point lines of the said matrix. 
     The five outputs of the said ROM 62 are connected to a parallel-series converter circuit 63 which transforms the 5 signals received from the 5 outputs into a series signal. It also adds a suitable number of blanks (e.g. 3) on to the end of the 5 signals to separate the characters horizontally. 
     Circuit 63 receives a clock signal from oscillator circuit 66 the frequency of which determines the width of each of the characters displayed on the screen. It also receives a LOAD signal &#34;L&#34; for each character (every 5+3=8 clock cycles in the example shown) from divider circuit 67 which, in turn, receives the clock signal from oscillator circuit 66. The signal thus received at the output of converter 63 is sent to combiner circuit 64 consisting of known logic elements (e.g. three 2-input AND gates each with a first input connected to the output of circuit 63 and a second connected to one of the outputs of circuit 65) which sends the said signal to one or more of its three outputs, marked R, G and B in the Figure, in response to the same number of control signals supplied by control circuit 65. The said outputs R, G and B are connected, in the known way, to the amplifier circuits of the color signals on the set so that the signals supplied by circuit 64 are added to the video ones of the received television signal. 
     Depending on the instructions received from circuit 65, it is possible to obtain the indications in any one of the three primary color combinations. 
     In FIG. 5, the control circuit 65 receives a control signal from an output of circuit 71 (port 4 of unit 11 in FIG. 1) so that the indications are displayed in green when the system is set to the first keyboard and yellow when it is set to the second. 
     Numbers 68, 69 and 70 indicate three switch circuits, similar to one another, controlled in parallel by a memory control signal DT supplied by a bit of port 1 of processing unit 11 in FIG. 1. Depending on the DT signal, these three switch circuits enable the FIG. 5 circuits to be set so as to load the data in memory 61 when the DT signal is present (high) and, vice versa, to set the same circuits for transmitting the data from the said memory to outputs R, G and B when the DT signal is absent (low) or when unit 11 is not transmitting characters to memory 61 (for display updating). To do this, when the DT signal is present, switches 68, 69 and 70 are positioned as shown by letter A in FIG. 5. This causes a reset pulse to be applied to terminals R2 and R3 of count circuit 60 and memory 61 is set to INPUT by the same DT signal applied to the input-output I/O control terminal. 
     Via switch circuit 68, count circuit 60 receives clock pulses DC from an output terminal of processing unit 11 of FIG. 1 (port 4). The same DC signal is also sent to the write control input &#34;W&#34; of memory 61. 
     In this way, for each clock pulse it receives, counter 60 supplies RAM memory 61 with addresses from 0 to 47. At the same time, unit 11 supplies the 48 signals (at port 4) received at the data input of the same memory so that they are memorized in the corresponding cells as a result of the &#34;W&#34; pulses. 
     When the DT signal is absent, on the other hand, (switches in position B), character counter 60 receives clock signals from circuit 66 via divider 67, reset signals with vertical scanning frequency fr at terminal R2, reset signals with horizontal scanning frequency FH at terminal R3 and a format-change signal &#34;F&#34; (controlled by a timer in processing unit 11, from processing unit 11. In this way, it supplies memory 61 with suitable addresses for arranging the 48 display characters in three 16-character lines, should signal &#34;F&#34; be present, or else it supplies the memory with only the first sixteen addresses for displaying a single 16-character line when signal &#34;F&#34; is absent. Alteernatively, character counter 60 can cut the size of the three sixteen character lines in half when the signal &#34;F&#34; is absent. Counter 60 also supplies combiner circuit 64 with a disabling circuit for disactivating it during the remaining television picture time. In this way, only a certain part of the screen is displayed, e.g. the top left-hand corner. If needed, the same disabling signal can be used for supplying a blank signal at an appropriate point in the television video amplification chain so as to blacken the background of the display to make the characters more visible. 
     A further output of circuit 71 (port 4 of unit 11) controls a switch, 72, between a BIP signal (which can be picked up at an appropriate point on the circuit, e.g. at the output of divider 7 of FIG. 1) and a first input of an adding circuit, 73, whose second input receives the audio B.F. signal of the received television signal picked up downstream from the manual volume adjuster. The output of the adding circuit is connected to the input of the B.F. amplifier, 74, on the set which pilots the loudspeaker 75. 
     In this way, under given circumstances, the processing unit 11 can control the sounding of an alarm for warning the user. The said circumstances may be: 
     (1) When the &#34;M&#34; memory key is pressed. The alarm reminds the user that the key has been pressed so as to prevent him from altering the content of the memory by mistake; 
     (2) when an unperformable instruction is given (e.g. the number of a non-existent channel or time) etc. 
     (3) when the maximum allowable limits have been reached for certain adjustments such as fine tuning corrections. 
     FIG. 6 gives a more detailed view of parts of circuits 12, 13, 14 and 15 in FIG. 1 showing memorization of the channels in the outside memory and maintenance of data during temporary power cuts. The said circuits 12, 13, 14 and 15 roughly correspond to the blocks marked 113, 100, 105 and 80 in FIG. 6. 
     Block 80 comprises a Zener diode, 83, connected between a +12 output of a supply circuit (&#34;AC&#34; voltage input, transformer 81 and rectifier 82) and a grounded resistor 84. The signal present at the resistor terminals is sent to an integrator circuit consisting of resistor 86, diode 87 and condenser 85. 
     The signal made available here, and inverted by inverter 88, is sent to inverter circuit 95 via integrator assembly consisting of resistor 93 and condenser 94, and also to the base of common-emitter transistor 90 via coupling resistor 89. The collector of transistor 90 is connected to a +5 supply voltage through resistor 92 and grounded through push-button switch 91 and supplies a reset signal to processing unit 11 (FIG. 1). 
     The +12 voltage is also supplied to the input of a stabilizer circuit 96 at the output of which, filtered by condenser 97, is made available the +5 supply voltage for supplying other circuits not shown in the Figure. The output of inverter 95 is connected to a first input of NAND gates 107 and 109 and to both inputs of NAND gate 106 which acts as an inverter. The output of the said gate 106 is connected to a reset input R4 of separator circuit 112 which receives the output signal of gate 107 at its disabling input C.D. via inverter circuit 110. Gate 107 receives a conditioning signal C.S. from processing unit 11 of FIG. 1 at its second input. The output of gate 107 is also connected to a disactivating input C.D. of memory 113. 
     A READ signal from processing unit 11 of FIG. 1 is sent via NAND gate 108, which acts as an inverter, to the read disabling &#34;NR&#34; input of memory 113. This input is also connected to a second input of gate 109 the output of which is connected to a write disabling &#34;NW&#34; input of the same memory 113. 
     The +5 voltage is also supplied to the anode of diode 101 at the cathode of which is connected a condenser, 104, the second terminal of which is grounded. Resistor 102 and 3 Volt battery 103, connected in series, are also connected parallel to condenser 104. The voltage available at the terminals of condenser 104 supplies memory 113, separator 112 and the 4 gates 106, 107, 108 and 109 contained in a single semiconductor body (CHIP). 
     Separator 112 has 5 inputs connected to 5 outputs of control circuit 111 (keyboard or remote-control receiver) and 5 outputs connected to 5 terminals of circuit 114 (port 5 of processing unit 11 in FIG. 1). 
     The same 5 outputs are also connected to 5 address inputs of memory 113. 
     The circuit described above operates as follows: 
     The function of block 100 is to generate a permanent supply voltage to keep memory 113 activated. In the event of a power cut, battery 103 supplies sufficient current to maintain the data in the memory through resistor 102. Vice versa, when power is being supplied from the mains, the +5 voltage is supplied to the memory via diode 101 and, at the same time, the battery is recharged slightly through resistor 102. 
     By means of Zener diode 83 and the integrator circuit comprising elements 85, 86 and 87, block 80 supplies a signal, at the output of inverter 95, after the +5 voltage, when the power supply is restored, and in advance of the said voltage when the power supply is cut off. In this way, the signals supplied by processing unit 11 to memory 113 cannot reach the memory during a power cut or during transient states. 
     Under the above conditions, gates 107, 108 and 109 are conditioned so as to protect memory 113 whereas gates 106 and 110 force separator 112 to supply a series of zeros at the output to prevent the memory from receiving chaotic address signals. 
     Block 80 also supplies, at the output of transistor 90, a signal similar to the one supplied by inverter 95 to keep processing unit 11 inactive during transient states and thus prevent uncontrolled operation. Push-button 91, however, enables a reset signal to be supplied manually to the said unit to commence the operation sequence from a preset point. 
     FIG. 7 shows a possible variation of one part of the circuit shown in FIG. 1. FIG. 7 only illustrates the parts which differ from FIG. 1 or which are connected differently. 
     Number 120 in FIG. 7 indicates a control keyboard which, besides the keys shown in FIG. 1 and not repeated here, comprises 6 keys marked &#34;V+&#34;, &#34;V-&#34;, &#34;L+&#34;, &#34;L-&#34;, C+&#34; and &#34;C-&#34;. The outputs of the said keyboard are connected to a group of input-output terminals 5 of processing unit 121 which is essentially the same as unit 11 in FIG. 1 from which it differs, among other things, by the provision of a further group of output terminals (ports) 6. 
     Six terminals of the said group are connected to six inputs of a digital/analogue converter 123 of the known type (e.g. consisting of a known network of R/2R resistors). The analogue output of the said converter is supplied to a switch circuit 124 with three outputs marked V, L and C in the Figure which are connected to three storage condensers 125, 126 and 127 respectively. Switch 124 also has two control input terminals connected to the remaining two output terminals of port 6 of unit 121 which receive the respective control signals for forwarding the analogue signal to one or other of condensers 125, 126 or 127. 
     The group of terminals or port 4 is connected to 8 input/output terminals of a RAM memory circuit 122. This replaces memory 12 of FIG. 1 from which it differs by the number of 8-bit cells (10×5 instead of 10×2). This memory also receives six address bits (instead of 5) from six output terminals (port 5) of unit 121. 
     The FIG. 7 circuit operates as follows: 
     When one of the six keys mentioned above is pressed (e.g. key &#34;V+&#34;), unit 121 supplies the character generating circuit with a combination of symbols which may be: 
     VVVVVVVV . . . . . 
     LLLLLL . . . . . . . 
     CCCCCCCCCCC . . 
     The line of symbols corresponding to the pressed key (V, L, C) is displayed with a different color from the rest. The number of characters per line is proportional to the corresponding analogue signal level (V, L, C) at that time. Whenever one of the + keys is pressed, the corresponding analogue level is increased 1/64 of maximum value. When an operation involving memorization is performed (e.g. whenever &#34;KEY&#34; operation mode is adjusted or the &#34;M&#34; key pressed), processing unit 121 transmits the relative data in digital form to memory 122 and has it memorized with much the same procedure already described and shown in FIG. 3. This means the data memory 122 is called upon to memorize for each of the 10 &#34;KEYS&#34; is of 5 types: channel, tuning, volume, brightness and color. For the sake of uniformity; the memory accepts 8-bit data whereas, the analogue adjustments, 6 bits, (64 levels) are more than enough so two bits are ignored. 
     Other ways exist of displaying analogue levels on the television screen using the character generator and circuit arrangement described in the present invention. Besides the one described above, the display could show any one of the following: 
     V*******&lt; 
     L***** 
     C********** 
     or: 
     VOLUME 40? 
     BRIGHTNESS 30 
     COLOR 50 
     or: 
     V+++++ 
     C- 
     In the first, the number of asterisks is proportional to the relative analogue signal level and the adjustment being made indicated by the symbol &#34;&gt;&#34;. In the second, the level is indicated by the number to the side of the adjustment item while the adjustment being made is indicated by the question mark. In the third, the number of &#34;+&#34; (or &#34;-&#34;) signs is proportional to the increase (or decrease) made to the preset nominal level. Of course, the preselected, memorized levels are preserved in memory 122, even in the event of a power outage, thanks to the precautions already described which also apply to the embodiment of FIG. 7. 
     It may prove useful to apply the sound alarm described in FIG. 5 for analogue adjustments too, for example, when the maximum level is reached. 
     The advantages of the present invention will be clear from the foregoing description. However, a number of variations can be made. For example, in the description, it was supposed a particular type of 8-bit microprocessor system was used with a separate CPU and ROM. It is possible, and even convenient, to use other types of microprocessors with a higher number of internal RAM registers (e.g. 128) or a so-called monochip containing an internal RAM and timer circuit, besides the ROM, or a 16-bit microprocessor. 
     It may even prove useful to fit the receiver with a remote-control. In this case, a keyboard similar to the one described is combined on the portable transmitter part of the remote-control system. A further variation, to avoid duplicating the control keyboard, could be to provide accommodation in the receiver housing with electric contacts in which to connect the transmitter part for operating the local control. 
     Many other variations can be made without, however, departing from the scope of the present invention. 
     For example, besides the key arrangement in FIG. 1 for controlling channel selection or FIG. 7 for controlling analogue levels (V, L, C), a number of different combinations can be used even using other control components different from keys or push-buttons.