Patent GB-1056197-A (GB)
Title: Input-output system
IPC: G06F13/12
Filed: 1965-05-14
Abstract: 1,056,197. Input-output systems for digital computers. GENERAL PRECISION Inc. May 14, 1965 [July 27, 1964], No. 20522/65. Heading G4A. An input output system (Fig. 2, not shown) communicates with the arithmetic section of a general purpose computer for transfer of words between the arithmetic section and one of two circulating registers R1, S1, the registers also being capable of carrying out internal operations, e.g. addition of S1 to R1 and communicating with external equipment for e.g. receiving inputs from tape readers or keyboards. Transfer to and from arithmetic section.-The address portion of an input-output instruction from the computer is fed into an input-output register 22, the states of flip-flops G1-G4 designating which of the glass line registers R1 or S1 is to receive the word and the flip-flops G5-G9 indicating the word position. When a write instruction G1, G3 is received, the contents of the A register (Fig. 1, not shown) are transferred to a one-word circulating register Z during the next word time. A word identifier register comprising flip-flops Q1-Q4 reads the four least significant bits P26-P23 of the R1 line each word time until coincidence with the flip-flops G5-G9 is achieved. The word is then transferred from the Z register to the selected position in the R1 or Z1 line. To transfer to the arithmetic section, a first instruction causes the selected word to be brought from the R1 or S1 line into the Z line when there is coincidence between the states of flip-flops G5-G9 and the register 26. The word is then passed via gates 30, 32 into A and C registers. Internal operations.-Corresponding to the four possible combinations of states of flip-flops R13, R14, the R1 line is capable of carrying out four internal logical operations, the last five bits of the words in the line being recirculated without alteration to preserve the word identification code. The register may recirculate through an adder 18 a word in the R1 line thus acting as a temporary store, a word in the S1 line may be added to the corresponding word in the R1 line, a carry from one word to the next word may be propagated, and one may be added to a word in the R1 line. In a similar way the S1 register may be made to recirculate, shift left, (by applying the word on the S 1 line to both inputs of the adder 20), add a special input and count down to zero a word in the S1 line. In particular, positive and negative pulses representing, for example, velocity increments along three axes may be stored in flip-flops V1-V3 and V4-V6 (Fig. 10, not shown) respectively, gates 60, 62 being enabled under the control of the word identifier register 26. The operation of " add S1 line " may then be used to perform integrations, distance terms along the three axes being accumulated in the R1 line. External operations.-Keyboard and tape reader inputs are read into the S1 line via flipflops V13, S12 (Fig. 11, not shown). Data may be assembled in seven groups of four bits each and during each cycle of the S1 line a control signal Dg is tested by the word code Q1-Q4 so that when valid data is presented flip-flop V8 is set followed by flip-flop V9 at P1 bit time to allow four bits to be transferred to the correct position in the S1 line.