GB1196348A - Improvements relating to Digital Data Processors - Google Patents

Abstract

1,196,348. Digital electric computer. ING. C. OLIVETTI & C. S.p.A. 11 April, 1968 [14 April, 1967], No. 17685/68. Heading G4A. A digital data processor controlled by a programme formed by a sequence of instructions includes a printer provided with a movable part, wherein the tabulation of the movable part along at least one co-ordinate is determined by stop means adapted to be set in predetermined stop positions and co-operating with means for effecting the tabulation movement, wherein each of the stop means is adapted to be set under the control of an instruction of the programme. A computer of the kind described in Specifications 1,196,346, 1,196,347 and 1,103,384 has an external printer constructed by a typewriter having tabulation means controlled manually by keys on the keyboard or by electromagnets, four instructions being provided: (1) carriage return, (2) partial carriage return, i.e. return to a position determined by a stop, (3) set tabulation stop, (4) horizontal tabulation, i.e. forward movement of the carriage until a stop is reached. The computer can also use instructions "tabulate by step according to the length specified" which shifts the carriage an amount specified by the instruction. Data circulating in the register travels with the least significant bit first. For read-out a tag bit B 1 is placed in the most significant bit under the control of shift register K stages K5, K6, K7, K8 acting as a counter by recirculating through the switching network. The counter is controlled by the signal T5 of each digit period and recirculating twice causing readout of the next digit when 31 digits have passed thus causing print-out of the digits in reverse order of circulating, i.e. most significant digit to least significant digit rather than vice versa. The computer includes an internal printer comprising a type cylinder kept in continuous motion and provided with as many vertical columns of type as there are columns of writing, each column having an arc free from type. A hammer normally at rest to the right of the cylinder is moved to the appropriate column for typing and depressed when the appropriate character is beneath it. Each character lies in a position in the column corresponding to the code number representing it in the machine. The printer prints from right to left the 16 function symbols, the eight registers and eight symbols indicating whole or divided registers, a space and ten decimal digits and decimal point and, if necessary, a decimal sign. A signal CK is generated just before each character is below the hammer position and a signal ST occurs during the passage of the character beneath the hammer. The printing of each number causes the return of the hammer to the right hand margin of the line. The maximum length of print is 23 digits. If more digits are required the computer stops the printing sequence, returns the hammer to the rest position line-spaces, positions the hammer below the least significant digit in the new line of print and resumes the printing sequence. The counter K in conjunction with the adder 72 counts 24 to place a tag bit B1 in register M to indicate where the data exceeds the maximum capacity of the line. Printing proceeds until bits B 1 are found in both registers N and M. This indicates end of line and automatic positioning of the hammer for print-out on a new line.