DATA TERMINAL WITH AUTOMATIC RESPONSE FEATURE
United States Patent 3743763
A data terminal which transmits binary-coded indicia representing characters in response to the operation of keys of a keyboard is provided with means different from the keyboard for automatically transmitting the representations of a particular plurality of characters in response to a remote inquiry.
US Patent References:
SELECTIVE CALLING LINE CONTROLLER FOR DETECTING AND GENERATING CODE CHARACTERS
Dalyai et al. - September 1970 - 3531772
Information handling apparatus
Bloch - April 1966 - 3248696
/3588371.html
Dal Monte - June 1971 - 3588371
Keyboard operated printer with electrical means preventing operation of plural keys
Jones, Jr. - February 1966 - 3232404
Encoder
Nicklas et al. - December 1966 - 3291910
SELECTIVE CALLING LINE CONTROLLER FOR DETECTING AND GENERATING CODE CHARACTERS
Dalyai et al. - September 1970 - 3531772
Information handling apparatus
Bloch - April 1966 - 3248696
/3588371.html
Dal Monte - June 1971 - 3588371
Keyboard operated printer with electrical means preventing operation of plural keys
Jones, Jr. - February 1966 - 3232404
Encoder
Nicklas et al. - December 1966 - 3291910
Inventors:
Jacobson, Allen G. (Ramsey, NJ)
Epstein, Maurice J. (Ardsley, NY)
Epstein, Maurice J. (Ardsley, NY)
Application Number:
05/150009
Publication Date:
07/03/1973
Filing Date:
06/04/1971
View Patent Images:
Export Citation:
Assignee:
Computer Transceiver Systems, Inc. (Paramus, NJ)
Primary Class:
Other Classes:
341/106
International Classes:
H04L12/06; H04L11/04
Field of Search:
340/365 178/26R,26A,23R,4 325/55 179/2DP
US Patent References:
| 3493928 | ELECTRONIC KEYBOARD TERMINAL CODE CHECKING SYSTEM | February 1970 | Juliusburger |
Primary Examiner:
Brown, Thomas W.
Claims:
What is claimed is
1. A data terminal for transmitting binary-coded combinations of indicia representing characters comprising a plurality of selectively operable means, each of said selectively operable means, when operated, generating at least one first signal associated with a different character respectively, an encoder means for encoding each of said first signals into a unique binary-coded combination of second signals, means for connecting said plurality of selectively operable means to said encoder means, means for converting said second signals to indicia for transmission, and controllably operable means independent of said plurality of selectively operable means for automatically generating a group of said first signals in a predetermined sequence, and means for operatively connecting said controllably operable means to said encoder means.
2. The data terminal of claim 1 wherein said plurality of selectively operable means is a keyboard device and further comprising means for preventing the generation of said first signals by said keyboard device when said controllably operable means is automatically generating said group of said first signals in the predetermined sequence.
3. The data terminal of claim 2 further comprising printer means for converting said binary-coded combinations of second signals to printed characters and means for preventing the operation of said printer means when said controllably operable means is automatically generating said group of said first signals in the predetermined sequence.
4. The data terminal of claim 1 further comprising manually operable means for activating said controllably operable means.
5. Th data terminal of claim 1 further comprising means for receiving remotely generated binary-coded combinations of indicia and means for sensing when a particular remotely generated binary-coded combination of indicia is received by said receiving means for activating said controllably operable means.
6. The data terminal of claim 5 further comprising manually operable means for activating said controllably operable means.
7. The data terminal of claim 6 wherein said plurality of selectively operable means comprise a keyboard device with a plurality of manually operable keys and further comprising means for preventing the generation of said first signals by said keyboard device when said controllably operable means is automatically generating a group of said first signals in a predetermined sequence.
8. The data terminal of claim 7 further comprising printer means for converting said binary-coded combinations of second signals to printed characters and meanS for preventing the operation of said printer means when said controllably operable means is automatically generating said group of said first signals in the predetermined sequence.
9. The data terminal of claim 1 wherein said plurality of selectively operable means comprise a keyboard device having a plurality of key-operated switches, each of said switches being connected to at least one output line, said encoder means includes a plurality of input terminals connected to said output lines and said controllably operable means includes stepping means for emitting a signal from each of a plurality of output terminals in a sequential order, the output terminals of said stepping means being connected to selected input terminals of said encoder means.
10. The data terminal of claim 9 further comprising means for receiving remotely generated binary-coded combinations of indicia and means for sensing when a particular remotely generated binary-coded combination of indicia is received by said receiving means for activating said controllably operable means.
1. A data terminal for transmitting binary-coded combinations of indicia representing characters comprising a plurality of selectively operable means, each of said selectively operable means, when operated, generating at least one first signal associated with a different character respectively, an encoder means for encoding each of said first signals into a unique binary-coded combination of second signals, means for connecting said plurality of selectively operable means to said encoder means, means for converting said second signals to indicia for transmission, and controllably operable means independent of said plurality of selectively operable means for automatically generating a group of said first signals in a predetermined sequence, and means for operatively connecting said controllably operable means to said encoder means.
2. The data terminal of claim 1 wherein said plurality of selectively operable means is a keyboard device and further comprising means for preventing the generation of said first signals by said keyboard device when said controllably operable means is automatically generating said group of said first signals in the predetermined sequence.
3. The data terminal of claim 2 further comprising printer means for converting said binary-coded combinations of second signals to printed characters and means for preventing the operation of said printer means when said controllably operable means is automatically generating said group of said first signals in the predetermined sequence.
4. The data terminal of claim 1 further comprising manually operable means for activating said controllably operable means.
5. Th data terminal of claim 1 further comprising means for receiving remotely generated binary-coded combinations of indicia and means for sensing when a particular remotely generated binary-coded combination of indicia is received by said receiving means for activating said controllably operable means.
6. The data terminal of claim 5 further comprising manually operable means for activating said controllably operable means.
7. The data terminal of claim 6 wherein said plurality of selectively operable means comprise a keyboard device with a plurality of manually operable keys and further comprising means for preventing the generation of said first signals by said keyboard device when said controllably operable means is automatically generating a group of said first signals in a predetermined sequence.
8. The data terminal of claim 7 further comprising printer means for converting said binary-coded combinations of second signals to printed characters and meanS for preventing the operation of said printer means when said controllably operable means is automatically generating said group of said first signals in the predetermined sequence.
9. The data terminal of claim 1 wherein said plurality of selectively operable means comprise a keyboard device having a plurality of key-operated switches, each of said switches being connected to at least one output line, said encoder means includes a plurality of input terminals connected to said output lines and said controllably operable means includes stepping means for emitting a signal from each of a plurality of output terminals in a sequential order, the output terminals of said stepping means being connected to selected input terminals of said encoder means.
10. The data terminal of claim 9 further comprising means for receiving remotely generated binary-coded combinations of indicia and means for sensing when a particular remotely generated binary-coded combination of indicia is received by said receiving means for activating said controllably operable means.
Description:
THE INVENTION
This invention pertains to data terminals and more particularly to data terminals with automatic answer back facilities.
In data communication networks wherein data terminals converse with each other it is often necessary for the terminals to identify themselves. In some networks the terminal operators stroke in the identification. However, at unattended terminals automatic means must be provided to respond to an identification inquiry. Heretofore, special mechanical code generators have been included in the terminal to provide the automatic response. Such code generators added to the complexity of the equipment and often duplicated some of the existing parts of the terminal.
It is an object of the invention to provide a data terminal with an automatic identification response facility which utilizes most of the preexisting elements of the terminal and only adds a minimum of extra equipment.
Briefly, the invention contemplates a data terminal for transmitting binary-coded combinations of indicia representing characters comprising a plurality of selectively operable means, each of which when operated generating at least one first signal associated with a different character. An encoder means connected to the selectively operable means encodes each of the first signals into a unique binary-coded combination of second signals. Means convert the second signals to indicia for transmission. In parallel with and independent of the plurality of selectively operable means is controllably operable means for automatically generating a predetermined sequence of the first signals which are also encoded to combinations of second signals by the encoder means.
Other objects, the features and advantages of the invention will be apparent from the following detailed description when read with the accompanying drawing which shows, by way of example and not limitation, apparatus for realizing the invention. In the drawing:
FIG. 1 is a block diagram of a data terminal according to an exemplary embodiment of the invention;
FIG. 2 is a schematic diagram of the keyboard of the data terminal of FIG. 1;
FIG. 3 is a schematic of the junction box in the data terminal of FIG. 1; and
FIG. 4 is a block diagram of the encoder of the data terminal of FIG. 1.
The embodiment of the invention will be described assuming positive logic wherein the more positive voltage (a high signal) represents the 1 state; and the less positive voltage (a low signal) represents the 0 state.
Data terminal 10 of FIG. 1 has for its main elements the modem 12, the printer 14, the encoder 16, the keyboard 18 and an automatic response generator centered around step counter 20 and flip-flop 22. In normal, i.e., non-automatic operation when an operator strokes a key of keyboard 18 a high signal is generated on its associated one of the lines K1 to KN which passes, via junction box and a corresponding line J1 to JN, to an input terminal of encoder 16. Encoder 16 transforms the signal received at the particular input to a corresponding binary-coded combination of high and low signals on the seven lines of cable E1-E7, assuming a seven-bit code for the characters. The coded combination of signals on the lines E1-E7 can be fed to printer 14 which prints a hard copy representation of the character under control of a strobe signal on line PS from encoder 16, via line E8, AND-curcuit 25 and OR-circuit 26.
In addition the coded combination of signals on the lines E1-E7 are fed to modem 12 where they are converted to a coded combination of tone signals which are fed, via, say, a telephone line to the receiver of a remote terminal (not shown). During normal reception of data, modem 12 receives the coded combinations of tone signals from a remote terminal, converts them to binary-coded combinations of high and low signals which are fed in parallel via the seven lines of cable M1 to M7 to printer 14. Printer 14 accepts the signals under control of a strobe signal on line PS from modem 12, via lines MS and via OR-circuit 26.
For automatic response operation flip-flop 22 is set to the 1-state, by a signal from OR-circuit 32. Automatic response can be initiated either by the operator at data terminal 10 by closing switch SW1 and applying a high voltage H to one input of OR-circuit 32, which normally receives a low voltage L via resistor R1, or from the remote terminal as indicated by a signal on line DS connected to the other input of OR-circuit 32 from the output of decoder 34. The inputs of decoder 34 are connected to the seven output lines M1 to M7 of modem 12. When modem 12 receives from the transmitter of the remote terminal (not shown) an inquiry character (a unique coded combination of tone signals) requesting terminal 10 to identify itself, decoder 34 senses the character and emits a pulse on line DS.
In either case, when flip-flop 22 is set to the 1-state by a signal at its S-input from the output of OR-circuit 32, line F1, connected to the 1-output, goes high and line F0, connected to the 0-output, goes low. Since line F1 is connected to one input of two-input AND-circuit 28 a path is connected from the clock 40 whose output is connected, via line CK, to the second input of AND-circuit 28 to the step input S of step counter 20 which is connected to the output of AND-circuit 28. It will be assumed that step counter 20 has five stages and that clock 40 is a free-running pulse generator having a pulse repetition rate below the maximum band transmission rate. The first pulse entering step counter 20 activates its first stage generating a signal on line S1 which is fed to junction box 24 where it is connected to one of the lines J1 to JN, the particular line being the line representing the first character of the automatic response. In a similar manner the second, third and four clock pulses sequentially generate signals of lines S2, S3 and S4 by stepping counter 20 to activate the second, third and fourth stages. Similarly lines S2, S3 and S4 are also connected to the appropriate ones of the lines J1 to JN representing the remaining characters of the response. The fifth stepping pulse from clock 40 steps the counter to the fifth stage, generating a signal on line S5 which is connected to the reset input R of flip-flop 22. The flip-flop is set to the 0-state dropping the signal on line F1 which blocks AND-circuit 28 and raising the signal on line F0. The automatic response cycle is terminated. However, while flip-flop 22 was set the signal on line F0 was low. This line is connected to keyboard 18 for controlling its operation. As will hereinafter become apparent, keyboard 18 requires a high signal on line F0 for it to operate. Therefore, whenever flip-flop 22 is set to the 1-stage, i.e., during the automatic response cycle, keyboard 18 is prevented from operating.
Similarly, when switch SW2 is closed (as shown) the state of flip-flop 22 controls the operation of printer 14. In particular line F0 is connected to one input of two-input AND-circuit 25 whose other input is connected to line ES from encoder 16. It will be recalled that encoder 16 emits a pulse on lines ES each time it encodes a signal from junction box 24. The output from AND-circuit 26 is connected via OR-circuit 26 and line PS to the strobe input S of printer 14. Since printer 14 will only print the character represented by the signals on lines E1 to E7 from encoder 16 when it receives a strobe pulse and since during tranSmission the strobe pulses are on line ES from encoder 16, the signal level on line F0 controls the operation of printer 14. Therefore, during the automatic response cycle when flip-flop 22 is set to the 1-state printer 14 does not hard-copy record the transmitted characters. However, by opening switch SW2 the control of AND-circuit 25 by flip-flop 22 is disabled and printer 14 always operates.
The details of the various elements of the data terminal 10 will now be described.
In FIG. 2 there is shown one possible embodiment of keyboard 18 which comprises N key operated switches KS1 to KSN, each representing a different character. Since all the switches are the same a typical switch KS1 associated with the character 1 will be described. The movable contact of switch KS1 is connected to the movable contact of contact set KCC of relay KL1 and the fixed contact of switch KS1 is connected to line K1 and via a resistor KR1 to a low voltage line L. Assume that the movable contact of set KCC is against the fixed contact connected to the high voltage line H, i.e., the normal condition. Then, whenever an operator depresses the key associated with character 1 the signal on line K1 goes from low to high indicating the entry of character 1. When the operator releases the key the switch springs back to the open state and line K1 reverts to the low voltage. When the signal on line F0 goes low current flows through the coil KLL of relay KL1 which attracts the moveable contact of set KCC to the fixed contact connected to the low voltage L. Then the movable contacts of all the key operated switches KS1 to KSN are connected to a low voltage. Thus, regardless of the position of switch KS1, line K1 will be low and no character can be manually entered.
Of course it should be realized that other types of keyboards can be used. For example, keyboards whose switches generate more than one signal when depressed can be used as well as keyboards with case shifting facilities. In addition, instead of using a relay to control the operation of the keyboard, one could profitably use solid state switches.
The junction box 24 shown in FIG. 3 provides parallel connections from certain lines K1 to KN and S1 to S4 to lines J1 to JN. In particular, each line K1 to KN is through connected, via an isolation diode, to a corresponding line J1 to JN. To add in the automatic response characters the lines S1 to S4 are connected, via isolation diodes, to the appropriate lines J1 to JN. In the example shown the automatic response word is assumed to be 112. Therefore line S1 is connected to line J1, line S2 to line J1 and line S3 to line J2. Line S4 remains unconnected. While only four lines S1 to S4 are shown, much longer answer back or response words could be generated by having more stages to counter 20 and more lines SN could be used. The disclosed junction box mates with keyboard 18. If other keyboards were used corresponding modifications would be made to the junction box. Furthermore, a discrete junction box plug board need not be employed but the required connections could be fixed wired from the lines SN to appropriate lines directly on keyboard 18.
The encoder 16 shown in FIG. 4 includes an encoding means which can be a conventional diode matrix type encoder or a read-only memory type encoder which emits a unique coded combination of signals in parallel on lines E1 to E7 in response to a signal on each of the lines J1 to JN. In addition, each of the lines E1 to E7 is connected to an input of OR-circuit 52 so that a signal is present on line ES, connected to the output of OR-circuit 52, each time a signal is encoded which can be used as a printer strobe. Modem 12 can be any of many conventional modulator-demodulators. For example, it can be of the type wherein in the modular section the coded combination of signals on lines E1 to E7 are fed in parallel to seven parallel tone generators each operating at a unique frequency and in the demodulator section there are seven tuned amplifiers in parallel, each tuned to one of the unique frequencies. There can also be used serial type modems wherein, in the modulator section, the seven parallel signals on lines E1 to E7 are serialized and used to shift a carrier signal between two frequency tones and in the demodulator section the frequency shift keyed tones are demodulated to serial pulses which are then distributed in parallel.
The printer can take many forms. A particularly useful printer is made by the National Cash Register Company and available as Model EM-T1-01. The modem can take many forms such as the DATASETS manufactured by the American Telephone and Telegraph Co. While only one embodiment has been shown and described in detail there will now be obvious to those skilled in the art many modifications and variations satisfying many or all other objects but which do not depart from the spirit of the invention as defined by the appended claims.
In particular, although the invention has been described with respect to a manual input terminal, it can be used with data terminals having magnetic and paper tape entries or even with remote telemetering data acquisition terminals.
This invention pertains to data terminals and more particularly to data terminals with automatic answer back facilities.
In data communication networks wherein data terminals converse with each other it is often necessary for the terminals to identify themselves. In some networks the terminal operators stroke in the identification. However, at unattended terminals automatic means must be provided to respond to an identification inquiry. Heretofore, special mechanical code generators have been included in the terminal to provide the automatic response. Such code generators added to the complexity of the equipment and often duplicated some of the existing parts of the terminal.
It is an object of the invention to provide a data terminal with an automatic identification response facility which utilizes most of the preexisting elements of the terminal and only adds a minimum of extra equipment.
Briefly, the invention contemplates a data terminal for transmitting binary-coded combinations of indicia representing characters comprising a plurality of selectively operable means, each of which when operated generating at least one first signal associated with a different character. An encoder means connected to the selectively operable means encodes each of the first signals into a unique binary-coded combination of second signals. Means convert the second signals to indicia for transmission. In parallel with and independent of the plurality of selectively operable means is controllably operable means for automatically generating a predetermined sequence of the first signals which are also encoded to combinations of second signals by the encoder means.
Other objects, the features and advantages of the invention will be apparent from the following detailed description when read with the accompanying drawing which shows, by way of example and not limitation, apparatus for realizing the invention. In the drawing:
FIG. 1 is a block diagram of a data terminal according to an exemplary embodiment of the invention;
FIG. 2 is a schematic diagram of the keyboard of the data terminal of FIG. 1;
FIG. 3 is a schematic of the junction box in the data terminal of FIG. 1; and
FIG. 4 is a block diagram of the encoder of the data terminal of FIG. 1.
The embodiment of the invention will be described assuming positive logic wherein the more positive voltage (a high signal) represents the 1 state; and the less positive voltage (a low signal) represents the 0 state.
Data terminal 10 of FIG. 1 has for its main elements the modem 12, the printer 14, the encoder 16, the keyboard 18 and an automatic response generator centered around step counter 20 and flip-flop 22. In normal, i.e., non-automatic operation when an operator strokes a key of keyboard 18 a high signal is generated on its associated one of the lines K1 to KN which passes, via junction box and a corresponding line J1 to JN, to an input terminal of encoder 16. Encoder 16 transforms the signal received at the particular input to a corresponding binary-coded combination of high and low signals on the seven lines of cable E1-E7, assuming a seven-bit code for the characters. The coded combination of signals on the lines E1-E7 can be fed to printer 14 which prints a hard copy representation of the character under control of a strobe signal on line PS from encoder 16, via line E8, AND-curcuit 25 and OR-circuit 26.
In addition the coded combination of signals on the lines E1-E7 are fed to modem 12 where they are converted to a coded combination of tone signals which are fed, via, say, a telephone line to the receiver of a remote terminal (not shown). During normal reception of data, modem 12 receives the coded combinations of tone signals from a remote terminal, converts them to binary-coded combinations of high and low signals which are fed in parallel via the seven lines of cable M1 to M7 to printer 14. Printer 14 accepts the signals under control of a strobe signal on line PS from modem 12, via lines MS and via OR-circuit 26.
For automatic response operation flip-flop 22 is set to the 1-state, by a signal from OR-circuit 32. Automatic response can be initiated either by the operator at data terminal 10 by closing switch SW1 and applying a high voltage H to one input of OR-circuit 32, which normally receives a low voltage L via resistor R1, or from the remote terminal as indicated by a signal on line DS connected to the other input of OR-circuit 32 from the output of decoder 34. The inputs of decoder 34 are connected to the seven output lines M1 to M7 of modem 12. When modem 12 receives from the transmitter of the remote terminal (not shown) an inquiry character (a unique coded combination of tone signals) requesting terminal 10 to identify itself, decoder 34 senses the character and emits a pulse on line DS.
In either case, when flip-flop 22 is set to the 1-state by a signal at its S-input from the output of OR-circuit 32, line F1, connected to the 1-output, goes high and line F0, connected to the 0-output, goes low. Since line F1 is connected to one input of two-input AND-circuit 28 a path is connected from the clock 40 whose output is connected, via line CK, to the second input of AND-circuit 28 to the step input S of step counter 20 which is connected to the output of AND-circuit 28. It will be assumed that step counter 20 has five stages and that clock 40 is a free-running pulse generator having a pulse repetition rate below the maximum band transmission rate. The first pulse entering step counter 20 activates its first stage generating a signal on line S1 which is fed to junction box 24 where it is connected to one of the lines J1 to JN, the particular line being the line representing the first character of the automatic response. In a similar manner the second, third and four clock pulses sequentially generate signals of lines S2, S3 and S4 by stepping counter 20 to activate the second, third and fourth stages. Similarly lines S2, S3 and S4 are also connected to the appropriate ones of the lines J1 to JN representing the remaining characters of the response. The fifth stepping pulse from clock 40 steps the counter to the fifth stage, generating a signal on line S5 which is connected to the reset input R of flip-flop 22. The flip-flop is set to the 0-state dropping the signal on line F1 which blocks AND-circuit 28 and raising the signal on line F0. The automatic response cycle is terminated. However, while flip-flop 22 was set the signal on line F0 was low. This line is connected to keyboard 18 for controlling its operation. As will hereinafter become apparent, keyboard 18 requires a high signal on line F0 for it to operate. Therefore, whenever flip-flop 22 is set to the 1-stage, i.e., during the automatic response cycle, keyboard 18 is prevented from operating.
Similarly, when switch SW2 is closed (as shown) the state of flip-flop 22 controls the operation of printer 14. In particular line F0 is connected to one input of two-input AND-circuit 25 whose other input is connected to line ES from encoder 16. It will be recalled that encoder 16 emits a pulse on lines ES each time it encodes a signal from junction box 24. The output from AND-circuit 26 is connected via OR-circuit 26 and line PS to the strobe input S of printer 14. Since printer 14 will only print the character represented by the signals on lines E1 to E7 from encoder 16 when it receives a strobe pulse and since during tranSmission the strobe pulses are on line ES from encoder 16, the signal level on line F0 controls the operation of printer 14. Therefore, during the automatic response cycle when flip-flop 22 is set to the 1-state printer 14 does not hard-copy record the transmitted characters. However, by opening switch SW2 the control of AND-circuit 25 by flip-flop 22 is disabled and printer 14 always operates.
The details of the various elements of the data terminal 10 will now be described.
In FIG. 2 there is shown one possible embodiment of keyboard 18 which comprises N key operated switches KS1 to KSN, each representing a different character. Since all the switches are the same a typical switch KS1 associated with the character 1 will be described. The movable contact of switch KS1 is connected to the movable contact of contact set KCC of relay KL1 and the fixed contact of switch KS1 is connected to line K1 and via a resistor KR1 to a low voltage line L. Assume that the movable contact of set KCC is against the fixed contact connected to the high voltage line H, i.e., the normal condition. Then, whenever an operator depresses the key associated with character 1 the signal on line K1 goes from low to high indicating the entry of character 1. When the operator releases the key the switch springs back to the open state and line K1 reverts to the low voltage. When the signal on line F0 goes low current flows through the coil KLL of relay KL1 which attracts the moveable contact of set KCC to the fixed contact connected to the low voltage L. Then the movable contacts of all the key operated switches KS1 to KSN are connected to a low voltage. Thus, regardless of the position of switch KS1, line K1 will be low and no character can be manually entered.
Of course it should be realized that other types of keyboards can be used. For example, keyboards whose switches generate more than one signal when depressed can be used as well as keyboards with case shifting facilities. In addition, instead of using a relay to control the operation of the keyboard, one could profitably use solid state switches.
The junction box 24 shown in FIG. 3 provides parallel connections from certain lines K1 to KN and S1 to S4 to lines J1 to JN. In particular, each line K1 to KN is through connected, via an isolation diode, to a corresponding line J1 to JN. To add in the automatic response characters the lines S1 to S4 are connected, via isolation diodes, to the appropriate lines J1 to JN. In the example shown the automatic response word is assumed to be 112. Therefore line S1 is connected to line J1, line S2 to line J1 and line S3 to line J2. Line S4 remains unconnected. While only four lines S1 to S4 are shown, much longer answer back or response words could be generated by having more stages to counter 20 and more lines SN could be used. The disclosed junction box mates with keyboard 18. If other keyboards were used corresponding modifications would be made to the junction box. Furthermore, a discrete junction box plug board need not be employed but the required connections could be fixed wired from the lines SN to appropriate lines directly on keyboard 18.
The encoder 16 shown in FIG. 4 includes an encoding means which can be a conventional diode matrix type encoder or a read-only memory type encoder which emits a unique coded combination of signals in parallel on lines E1 to E7 in response to a signal on each of the lines J1 to JN. In addition, each of the lines E1 to E7 is connected to an input of OR-circuit 52 so that a signal is present on line ES, connected to the output of OR-circuit 52, each time a signal is encoded which can be used as a printer strobe. Modem 12 can be any of many conventional modulator-demodulators. For example, it can be of the type wherein in the modular section the coded combination of signals on lines E1 to E7 are fed in parallel to seven parallel tone generators each operating at a unique frequency and in the demodulator section there are seven tuned amplifiers in parallel, each tuned to one of the unique frequencies. There can also be used serial type modems wherein, in the modulator section, the seven parallel signals on lines E1 to E7 are serialized and used to shift a carrier signal between two frequency tones and in the demodulator section the frequency shift keyed tones are demodulated to serial pulses which are then distributed in parallel.
The printer can take many forms. A particularly useful printer is made by the National Cash Register Company and available as Model EM-T1-01. The modem can take many forms such as the DATASETS manufactured by the American Telephone and Telegraph Co. While only one embodiment has been shown and described in detail there will now be obvious to those skilled in the art many modifications and variations satisfying many or all other objects but which do not depart from the spirit of the invention as defined by the appended claims.
In particular, although the invention has been described with respect to a manual input terminal, it can be used with data terminals having magnetic and paper tape entries or even with remote telemetering data acquisition terminals.