Patent GB-1204461-A (GB)
Title: Terminal apparatus for transmitting and receiving data
IPC: G06F13/38
Filed: 1969-01-20
Abstract: 1,204,461. Printer control circuits. ING C. OLIVETTI & C. S.p.A. 20 Jan., 1969 [19 Feb., 1968], No. 3183/69 Heading G4H. Apparatus for transmitting and receiving data comprises a recirculating serial store having a succession of cells for storing characters, a display device for visually displaying the data in the store and a selectively actuable printing device for producing a record of data in the store, the printing device operating asynchronously with respect to the cycles of the store. The store is a delay line containing 256 cells each having ten bit positions to receive a character represented by seven bits, two marker bits and a parity bit. The store has an output 11 and an input 10, the recirculating data passing through a ten-position register 22 which is used both for entering data into the store and for reading it out. A second register 51 having 9 positions is connected to register 22 via gates for the transfer of characters in parallel. The parity bit is stored in the tenth position of the register 22 and is entered by a parity bit generator consisting of a divide-by-two counter 26. The first bit position (R1) of a cell contains a write bit which is read from one cell and entered over line 21 into the next to indicate the cell in to which successive characters are to be entered. The second bit position (R2) contains a read bit which if present causes the character in the register 22 to be transferred to the register 51. The read bit is transferred to the next cell. Data can be entered into the store from a keyboard 1 over lines 71. A CAR signal is generated by the control circuit 27 to open the read-in gate to register 22 connecting lines 71 to lines 74. Data can also be entered from a computer, the signals being converted to parallel on lines 75. Thus data is gated (by signal ICCA) first into register 51, and thence gated (by signal CAL) to register 22. For the purpose of display the characters are gated in turn from register 22 via register 51 to a decoder 54 which has an output lead for each possible character. Each of these leads links a pattern of cores in a character generator 55. The seven lines of the generator are gated in turn by counter 57 to a serializer 59 and applied to a cathode ray tube 98. The counter 57 advances one step each cycle so that all the top lines of the characters in the store are applied to the cathode ray tube in the first cycle, the second lines in the second cycle and so on. The process repeats at high speed to give a steady display. On the CRT screen the characters are arranged in eight rows of 32. When a print key is pressed on the keyboard the detection of the read tag bit opens a gate to pass the contents of register 22 to register 51. It also sets flip-flop 78 to produce signal PRC to gate the contents of register 51 over line 19 to the printer. After the printer has operated it sends a signal CUT to reset the flip-flop, the reset signal STAC then enabling the next character to pass from register 22 to register 51. The format of the matter printed can be varied by a special character, entered in the store from the keyboard to cause the printer to return to the beginning of the next line, thereby controlling the length of line. A special key erases this code. A " partial printing " key is operated when it is desired to print only part of the contents of the store. Tags are thereby entered in the store at suitable points, selected from the CRT display, to print only the matter between each tag and the end of the corresponding rows. Specifications 1,196,827, 1,196,828, 1,196,829 and 1,131,834 are referred to.