US3643022A - Teleprinter apparatus with electronic speed control - Google Patents

Teleprinter apparatus with electronic speed control Download PDF

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Publication number
US3643022A
US3643022A US817327A US3643022DA US3643022A US 3643022 A US3643022 A US 3643022A US 817327 A US817327 A US 817327A US 3643022D A US3643022D A US 3643022DA US 3643022 A US3643022 A US 3643022A
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register
character
bits
frequency
timing
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Luigino Ferroglio
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Telecom Italia SpA
Olivetti SpA
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Olivetti SpA
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/14—Two-way operation using the same type of signal, i.e. duplex
    • H04L5/1438—Negotiation of transmission parameters prior to communication
    • H04L5/1446—Negotiation of transmission parameters prior to communication of transmission speed

Definitions

  • the present invention relates to a teleprinter.
  • Known teleprinters usually consist of two distinct parts: a transmission unit and a receiving unit.
  • the transmission unit consists of an input keyboard, control device and serialization device for passing the data fed into the keyboard to the transmission line in a serially coded form, each item being preceded by a start bit and followed by a stop bit, in accordance with the telegraphic transmission procedure of the asynchronous type.
  • the receiving unit consists of a distributor (parallelizing device) for the serially coded data received from the transmission line, a control device, and a printout device by which the data received is reproduced.
  • the upper limit of telegraphic speed i.e., of the number of telegraphic impulses that can be transmitted or received per unit of time, is determined by the transmission line.
  • the telegraphic speed below the limit determined by the line, is varied by means of a gear change on the motor shaft.
  • the fact is that the telegraphic speed in the case of a teleprinter cannot be varied by acting directly on the motor of the machine, since it is not possible to modify the speed of the motor with the required degree of accuracy. It is therefore only by acting on the mechanical gearing which transmits the movement of the motor shaft of the machine to the devices which effect all the established functions that the speed with which these functions can be actuated, i.e., the telegraphic speed, can be varied accurately.
  • the operation of varying the gearing has the effect of varying the load on the motor of the machine, so that the ballast resistance of the motor has to be regulated.
  • This method of modifying the telegraphic speed in known teleprinters further entails fatigue and consequent wear of the mechanical components, since they are forced to operate at speeds different from that for which they are dimensioned.
  • the presence of the gear change and of the set of ballast resistances has the effect, in the known apparatus, of considerably increasing the cost incurred and the space occupied.
  • the object of this invention is to overcome such drawbacks.
  • teleprinter apparatus comprising a transmission or receiving unit which includes a register and a timing device which emits timing pulses which time the serial readout to line of the bits of a character entered in the register from an input device, or which time the shifting into the register of bits received from line for transfer of a character to an output device, the timing device comprising an oscillator feeding a frequency divider and a manually operable selection network for selecting outputs at different frequencies from the divider to constitute the said timing pulses.
  • FIG. 1 is a block diagram of the transmission unit of apparatus embodying the invention
  • FIG. 2 is a block diagram of the receiving unit of the apparatus.
  • FIG. 3 shows diagrams relating to the control of the stepbystep reader, for telegraphic speeds of 50 baud and 100 bauds.
  • the teleprinter embodying the invention consists of a transmission unit and a receiving unit.
  • the transmission unit inFIG. 1 comprises, by way of input devices, a keyboard TA, a punched tape reader LA, and an automatic reply device RA which conveys the address of the unit at the request of the correspondent or when called for by means of the keyboard.
  • the keyboard TA is a normal keyboard, similar to that of a typewriter, with the addition of keys for the issuance of service codes and keys for special functions, and in which a certain configuration of code bars corresponds to each key.
  • the code keyboard may be of the type described in the specification of our US. Pat. No. 3,306,4l7.
  • the code bars provided act on microswitches which supply electrical signals corresponding to the said bars, and another microswitch is actuated simultaneously with a key and supplies a control signal VT indicating that the transmitting unit is being used by the keyboard.
  • the machine is also provided with a starting key for the punched tape reader LA.
  • the tape' reader can be of the type described in the specification of our U.S. Pat. application Ser. No. 793,830.
  • the starting key of the reader LA actuates a microswitch which supplies a control signal VL indicating that the transmitting unit is being utilized by the tape reader.
  • the automatic reply device RA is started by a key provided in the machine or by a signal emanating from the receiving unit.
  • the starting key causes a microswitch to produce a control signal VR showing that the transmission unit is being utilized by the automatic reply device RA.
  • the control signal is supplied directly by the signal emanating from the receiving unit if it is by this latter that the automatic reply device is started up.
  • The'automatic reply device RA can consist, e.g., as described in the specification of US. Pat. application Ser. No. 714,488 assigned to the assignee of this invention, of a drum to the periphery of which are connected shaped strips, each representing 'a certain combination of codes. The drum rotates by one step'at a time, presenting the shaped strips to feelers. These latter act on eight microswitches, which provide the electrical signals corresponding to the eight code bitspresented on the scanned strip and representing one single character.
  • path 1 is opened by signals which are the complements of the control signal VL emanating from the tape reader LA and the control signal VR emanating from automatic reply device RA, both acting on a gate 10.
  • the data keyed in will only enter the register M provided that no item is coming at the same time from the tape reader of the automatic reply device.
  • path 2 for the data emanating from the tape reader LA, is opened by the complemented signals VT and VR emanating respectively from the keyboard TA and from the automatic reply device RA and applied to a gate 11.
  • path 3 for the data emanating from the automatic reply device RA, is opened by the complemented signals VT and VL emanating respectively from the keyboard TA and from the tape reader LA and applied to a gate 12.
  • each control signal VT, VL and VR enables a timing device via a gate 13.
  • the purpose of this latter is to supply the intervals of the individual bits of the characters emerging from the register M and directed to the transmission line L.
  • the length of the bit intervals is fixed by the operator of the machine, who by means of a speed selection switch 22 acts directly on electronic time bases, while the mechanical units of the machine always function at the same speed.
  • the timing device gives a signal K which causes to be read into the register M the alpha-numerical character or code expressing a function, emanating from the keyboard or from the reader or from the automatic reply device, according to whether path 1, 2, or 3 is open. Let us suppose that a character has been selected on the keyboard TA: the open, gate 10 will then be open, while gates l l and 12 are at the same time blocked.
  • the timing device has been started up on the switching-on of the machine, so that after the receipt of the signal VT, i.e., after the latter has enabled the gate 13, it supplies the intervals of the bits of the character to be transmitted, of the length selected by the operator, acting on the telegraphic speed selection switch 22.
  • the timing device will then supply the eight intervals D1 D8 of the eight bits of the character.
  • a start bit and a stop bit are necessary before and after the character, respectively, and the timing device then also supplies the interval of the DST start bit and the interval of the DSP stop bit, which go directly into the line L.
  • the timing device supplies the right intervals D1 D8, applied to gates 14 21, respectively, at the output of the eight flip-flops Ml M8, respectively, which constitute the register M. Then, in a sequence determined by the signals D1 D8 generated by the timing device, the bits of the stored character pass into the line from the register M.
  • the timing device supplies the interval DSP directly to the line L, so that in the line a signal level is present which represents the stop for the interval of a bit and which remains such until the succeeding start signal DST, even if the timing device, after the interval DSP, is blocked, owing to the extinction of the VT signal which actuates the gate 13, as a result of the said DSP signal. Subsequently, when a further character is keyed in, the aforementioned process is repeated, i.e., the character from the keyboard passes to the register M, and from there, with the delay produced by the timing device, it is shifted into the line.
  • the transmission of the characters is effected from the tape reader LA and from the automatic reply device RA.
  • the tape reader similar to that described in the specification of the aforementioned application Ser. No. 793,830, is a step-by-step reader.
  • the reader as already mentioned, is started up by a command present in the machine, SLA, which supplies the signal VL. This signal prevails until the reader is blocked by another key present in the machine.
  • the timing device Owing to the continuous presence of the VL signal the timing device is still in operation, continuously forming time intervals corresponding to the start, to the eight character bits and to the stop, then again to the start, to the eight bits and to the stop, and so forth.
  • the characters read by the tape reader must be present in the M-register at each start, i.e., the M-register must be refilled at each start.
  • the reader being a step-by-step reader, operating continuously from character to character, must receive the command signal for reading and simultaneous feed.
  • the time cycle ofthe tape reader itself fixes the interval of time between the energization of the reading command electromagnet and the moment when the character read is actually available to the output microswitches of the reader, and, also as described in the above-mentioned specification, the character only remains available for a very short period. Consequently, the moment for the energization of the electromagnet for the reading command is governed by the decoding operated by the timing device for the bit intervals, and the fact is that if, within a DST interval, the character read by the tape reader is to be available in the register M, the same reader must be energized in advance by a definite selected interval of time.
  • This command for the energization of the aforementioned electromagnet is given by the decoding of that bit interval which is distant from the start interval by the said definite selected interval of time.
  • the decoding of the bit interval which gives the reading command thus varies with the telegraphic speed, since an alteration of the latter results in an alteration of the interval of time between the start interval DST and the individual bit intervals. Consequently, the decodings of the bit intervals Dl D8 enter a selection network 33, to which six different signals generated by the speed change switch 22 likewise have access.
  • each speed is associated a corresponding decoding of the bit intervals Dl D8, so that from the selection network 33, a signal AVL emerges, at a moment which varies according to the speed, and enters the gate 34 which is enabled by the signal VL, and from which emerges a signal AVLA which energizes the reading command electromagnet of the reader LA.
  • the output microswitches of the latter are placed according to the character which has been read and is available at the path 2, and thus, after the gate 11 is actuated by the decoding of the start bit DST, is available at the register M.
  • the character can thus be extracted in successive bits, in view of the aforementioned synchronization between the operation of the reader and the serialization.
  • FIG. 3 gives the time diagram of the reading command of the reader LA, in the example based on two telegraphic speeds of 50 and baud.
  • the diagram D100 in FIG. 3 shows the bit intervals in the case of telegraphic transmission at I00 baud. It is noted that the character read by the reader LA at an instant within the DST start interval is to be available in the register M. The character remains available at the output microswitches of the reader LA for an interval of time represented by a signal DIS.
  • the fixed time of the reader LA itself, lasting up to the moment at which the character read is to be available to the output microswitches of the reader, from the moment when the reading command is given, is identified by the letter
  • the reading command AVLA must be given by decoding the bit interval D5.
  • the reading command AVLA must be given by decoding the bit interval D8.
  • the selection of the bit interval to be decoded is made by selection network 33 under control of the signal a to f selected by switch 22.
  • the automatic reply device RA is likewise a device with a step-by-step feed. It is started up by a key SRA present in the machine or by a signal RlC emanating from the function decoding assembly present in the receiving unit. The aforementioned signals generate a VR signal which is present con- 4 tinuously. In this case likewise, therefore, the timing device continues in operation, supplying trains of lO-bit intervals. The characters read by the device RA, therefore, must at each start be available at the register M.
  • the automatic reply device does not merely act on the output switches for a short space of time, and the latter remain in action until the new positioning operation, so that any decoding signal of the bit intervals DST, Dl D8, can be taken for the purpose of subsequently giving the command for feed and reading of the aforementioned device RA.
  • the signal DST after passage through gate 35 actuated by the signal VR supplies, on each character cycle, the feed and reading order to the automatic reply device RA, energizing the electromagnet present in the apparatus and provided for this purpose.
  • the speed change system provided for the transmission according to the invention enables the telegraphic speed of the messages to be varied without modifying the speed of the mechanical component of the machine, such as the keyboard, the tape reader and the automatic reply device.
  • the speed with which the keys are operated must be less than the minimum possible telegraphic speed, in order to ensure that the character keyed in is passed to line before the subsequent character is keyed in and that no characters will thus be superimposed in the register M.
  • the speed of the reader and of the automatic reply device need not be limited, because the two devices, after a character has been supplied, will come to a stop and will not restart until the order is given by the timing device, at the end of the serialization of the preceding character.
  • the change of speed is obtained by acting directly on the timing device which determines the out put sequence of the bits.
  • an oscillator 23 which is started up when the machine is set in operation, generates a square wave of a certain frequency which feeds certain stages of a frequency divider 24, of a known type.
  • the different outputs of the stages of the aforementioned-divider 24 are in their turn conveyed to a selection network 25 which also receive the six signals a, b, c, d, e and f, generated by switches constituting the speed selection switch 22, which is provided on the outside of the machine and which can be used by the operator for varying the speed.
  • the positions of the selection switch on the outside of the apparatus are six in number, corresponding to the six different telegraphic speeds 50, I00, lSO, 200, 300 and 400 baud.
  • the selection network 25 whose input includes the signals a to f emanating from the six switches and also the outputs of the stages of the frequency divider 24, serves to select, in accordance with the signal emanating from the selection switch 22, the frequencycorresponding to the position of the said selection switch, among the six different frequencies obtained by the division of the aforementioned divider.
  • the selection network therefore emits the frequency signal equal to that selected with the selection switch 22 and, if the gate 13 is actuated by one of the track signals VT, VL and 'VR emanating from the input devices TA, LA and RA, respectively, the frequency signal enters a counter 26 which counts in tens.
  • the signals From the counter 26 the signals enter a decoding circuit 27 which supplies the interval DST, which is the initial starting interval, the character intervals D1 D8 and the stop interval DSP.
  • the decoding of the internal DSP prevents the signal VT from being emitted by the keyboard TA and thus likewise blocks the counter 26, which will once again initiate the counting operation when the subsequent character is keyed in,
  • the signals representing the start and stop intervals go direct to the line, while the signals D1 D8 actuate the gates 14 21, respectively, for the emission in sequence, of the bits stored in the flip-flops Ml M8 of the register M.
  • the register M is fed with the character emanating from the keyboard or from the tape reader or from the automatic reply device, when enabled by the signal K having the desired frequency and emanating from the selection network 25 and from the gate 13. Since the telegraphic speed is thus modified solely by action at the electronic level, all the mechanical components of the machine maintain the speed for which they are designed and are, therefore, not subjected to any unforeseen fatigue or undesirable irregularity.
  • the receiving unit receives the coded characters emanating from the line and expressing alphanumerical data which, in particular, can be supplied to a printing unit and a tape punch, or data expressing function commands which are to be carried out by the unit.
  • the data consisting of 7+1 bits preceded by a start bit and followed by a stop bit arrive from the transmission line at a rate determined by the transmission speed selected.
  • the bits enter in series into a shift register I of a type already known in itself and consisting of bistable flip-flops.
  • a timing device serves to shift the entering bits, according to the speed selected by the operator by means of a switch 42 and being naturally the same speed as that of the bits which arrive from the line.
  • a signal PR1 emerging from the timing device therefore causes a shift, into the register I, of the entire character preceded and followed by the start bit and the stop bit, respectively.
  • the stop bit is present in the flip-flop I1, i.e., when the entire character is stored in the register I, the start bit of the subsequent character arrives from the line, so that, since the interval between the eighth bit of the first character and the subsequent start bit of the second character is too short by comparison with the time required for the form, such as interlining,
  • the said character is stored in another register ll, after the actuation of a gate 53.
  • Actuation of that gate is caused by the signal S, effected by a decoding circuit 54, which senses the presence of the start bit in the flip-flop l 10, thereby confirming the complete introduction of the first character into the register I.
  • the first character, emanating from the line L thus passes to the register II, where it is present for the space of time corresponding to one character, i.e., until the subsequent character, emanating from the line, has been completely introduced into the register I.
  • the motor 61 of the machine On the arrival of the first character emanating from the line, the motor 61 of the machine is started up and sets in operation a timing device 62, of which the timing cycle is, for example, shorter than the interval of a character. Within this timing cycle, all the functions of the machine are actuated.
  • the timing device 62 in particular, consists of a disc of insulating material, which rotates synchronously with the motor shaft and of which the periphery bears a plate of magnetic material, by which on each rotation, a magnetic detector, which scans the periphery of the disc, supplies a signal On each new character, i.e., if the signal S, which represents the decoding of the flipflop I 10 of the register I, confirming the presence of the start bit in the aforementioned flip-flop, opens a gate 55, a signal Z emerges from this gate and, by actuating agate 56, enables the character stored in the register II to pass to a third register Ill.
  • the character present in the register III can be an item which is to be printed and punched or a function command which can be punched and not printed. In either case, as soon as a character is present in the register III, eight electromagnets 63, corresponding to the respective bits of the character, are energized or deenergized, according to the code In particular, the electromagnets can position code bars of a printing device of the kind described in the specification of our US. Pat. No. 3,356,198. At the same time, the character present in the register III is decoded by a decoding block 64 for the function codes.
  • the function decoding block energizes an electromagnet 65, which controls a printer striking bar, so that the character corresponding to the arrangement already selected for the code bars is printed and the function decoding block 64 at the same time energizes an electromagnet 66 which causes the carriage to be fed forward by one step. If the character decoded by the decoding block 64 represents a function which the machine is to perthe return of the carriage, a return movement by one step, then the striking bar of the printing unit remains inoperative, while the appropriate one of three electromagnets 67, 68 and 69, which actuate the respective decoded functions, is energized.
  • the character present in the register III furthermore, excites eight electromagnets 70, which position the corresponding bars of a punch, while the function decoding block 64 supplies, for each character, a command signal for the punching, which energizes an electromagnet 71. If the character present in the register III is not to be punched, the electromagnet 71 is not energized, and the electromagnets 63 and also the electromagnets 70 remain ineffective.
  • the function decoding block 64 emits a signal RIC which sets in operation the automatic reply device RA, thus leaving the bars of the printing device and the bars of the punching device inoperative.
  • the bits of the characters received occur at a rate which is determined by the transmission speed, which must be the same as the shifting speed of the character in the register I.
  • the transmission speed is decided by the two operators stationed at the communication units at the ends of the line.
  • the operator responsible for the receiving unit uses his speed change switch 42 which, in particular, selects one of the speeds 50, 100, 150, 200, 300, and 400 baud.
  • the signals g, h, i, l, m, and n, emanating from the six switches. enter a selection network 43.
  • the selection network 43 also receives six different signals with six different frequencies corresponding to the six different positions of the speed change switch 42.
  • an oscillator 44 generates a square wave ofa certain frequency, which feeds a several stage frequency divider 45, known in itself and producing the respective signals representing the six different frequencies required.
  • the purpose of the selection network 43 is therefore to select in accordance with each of the signals g, h, i, I, m, and n, emanating from the speed change switch, the frequency corresponding to the position of the switch, from among the six frequencies obtained by the division by the aforementioned divider 45.
  • the signal PR1 With the same frequency as that in which the bits of the character received occur in succession, effects the "shift,” in the register lofthe bits ofthe received character.
  • the speed variation is thus effected at an electronic level, at the input of the control of the machine without acting on the mechanical components of the apparatus, such as the printing device and the punching device, which thus can continue to operate at the same speed at all times.
  • this same speed also in the case of the transmitting unit refers to the speed with which a mechanical cycle is executed, not the rate with which the cycles follow one another.
  • a transmitting apparatus including a teleprinter unit conditionable for processing code combinations cyclically at predetermined speed, a keyboard for entering a character comprising bits comprising one ofsaid combinations, a register connected to said keyboard for temporarily storing the bits of the character code combination being processed, and a timing device for rhythmically controlling the connection of said line with said register, said timing device including an oscillator for generating timing pulses at a predetermined frequency, and a transmission speed adapter comprising:
  • a frequency divider for dividing the output of said oscillator to generate timing pulses corresponding to a plurality of operating frequencies, said transmission speed corresponding to one of said operating frequencies
  • a frequency selection network receiving the output pulses of said frequency divider and providing timing pulses corresponding to said operating frequency
  • a manually operated switch coupled to said selection network to select the operating frequency of said network and including a plurality of outputs, each of said outputs associated with one ofsaid operating frequencies,
  • decoder means coupled to said counter means for generating signals to time the individual bits of the character of said code combination and for generating a cyclic signal
  • telegraphic system including a transmission line operating at a transmission speed, a transmitting apparatus including a teleprinter unit conditionable for processing code combinations cyclically at predetermined speed, an input device operating to supply characters in a step-by-step sequence, each of said characters comprising bits comprising one of said code combinations, a register connected to said input device for temporarily storing the bits of the character code combination being processed and a timing device for rhythmically controlling the connection of said line with said register, said timing device including an oscillator for generating timing pulses at a predetermined frequency, and a transmission speed adapter comprising:
  • a frequency divider for dividing the output of said oscillator to generate timing pulses corresponding to a plurality of operating frequencies, said transmission speed corresponding to one ofsaid operating frequencies
  • a manually operated switch to select the operating frequency of said network including a plurality of outputs, each of said outputs associated with one of said operating frequencies,
  • a frequency selection network receiving the output pulses of said frequency divider and responsive to said switch to provide timing pulses corresponding to said operating frequency
  • decoder means coupled to said counter means for generating signals to time the individual bits of the character of said code combination and for generating a cyclic signal
  • said supplying means including a second selection network controlled by said manually operated switch for selecting different ones of the decoder signals to constitute said command signal.
  • said teleprinter unit comprises a receiving unit including a shift register receiving the timing pulses as shift pulses for received character bits
  • said decoder means including means for generating a second cyclic signal when all the bits of a character are stored in the shift register,
  • a second additional register controlled by a third cyclic signal having a frequency higher than the frequency of said second cyclic signal corresponding to a maximum transmission speed for causing the bits stored in said first additional register to be transferred to said second additional register whereby the bits stored in said first additional register are transferred to said second additional register before all bits of the next character have reached the said second shift register.

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US817327A 1968-04-18 1969-04-18 Teleprinter apparatus with electronic speed control Expired - Lifetime US3643022A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4191848A (en) * 1978-09-25 1980-03-04 Kahn William M Teletypewriter motor controlling
EP0068831A2 (en) * 1981-06-26 1983-01-05 Honeywell Information Systems Inc. Address setting for computer terminal unit

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US2712037A (en) * 1953-05-07 1955-06-28 Rca Corp Electronic transmitter-distributor
US2916727A (en) * 1955-05-10 1959-12-08 Itt Data processing system
US2945092A (en) * 1956-11-27 1960-07-12 Teletype Corp Start-stop telegraph signal generator with two oscillators
US3011022A (en) * 1957-11-01 1961-11-28 Teleregister Corp Electronic receiving distributor
US3012096A (en) * 1956-01-13 1961-12-05 Western Union Telegraph Co Telegraph tape transmitter distributor
US3059048A (en) * 1961-02-23 1962-10-16 Itt Automatic teletypewriter transmitter
US3296370A (en) * 1962-04-03 1967-01-03 Scm Corp Communications equipment transmitter and tape recorder
US3419678A (en) * 1965-04-26 1968-12-31 Clary Corp Data printing system
US3457368A (en) * 1965-11-15 1969-07-22 Bell Telephone Labor Inc Code character keyboard sender
US3558821A (en) * 1968-02-12 1971-01-26 Siemens Ag Teleprinter device utilizing receiver formed from electronic circuits

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2712037A (en) * 1953-05-07 1955-06-28 Rca Corp Electronic transmitter-distributor
US2916727A (en) * 1955-05-10 1959-12-08 Itt Data processing system
US3012096A (en) * 1956-01-13 1961-12-05 Western Union Telegraph Co Telegraph tape transmitter distributor
US2945092A (en) * 1956-11-27 1960-07-12 Teletype Corp Start-stop telegraph signal generator with two oscillators
US3011022A (en) * 1957-11-01 1961-11-28 Teleregister Corp Electronic receiving distributor
US3059048A (en) * 1961-02-23 1962-10-16 Itt Automatic teletypewriter transmitter
US3296370A (en) * 1962-04-03 1967-01-03 Scm Corp Communications equipment transmitter and tape recorder
US3419678A (en) * 1965-04-26 1968-12-31 Clary Corp Data printing system
US3457368A (en) * 1965-11-15 1969-07-22 Bell Telephone Labor Inc Code character keyboard sender
US3558821A (en) * 1968-02-12 1971-01-26 Siemens Ag Teleprinter device utilizing receiver formed from electronic circuits

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4191848A (en) * 1978-09-25 1980-03-04 Kahn William M Teletypewriter motor controlling
EP0068831A2 (en) * 1981-06-26 1983-01-05 Honeywell Information Systems Inc. Address setting for computer terminal unit
EP0068831A3 (en) * 1981-06-26 1985-12-18 Honeywell Information Systems Inc. Address setting for computer terminal unit

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DE1919848A1 (de) 1969-11-06
FR2006425A1 (ko) 1969-12-26

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