Patent GB-809623-A (GB)
Title: Apparatus for transferring coded data from a record member to a multi-word register associated with a digital computer
IPC: G06F7/22
Filed: 1956-11-01
Abstract: 809,623. Digital electric calculating-apparatus; electric digital-data-storage apparatus; collating digital data. NATIONAL CASH REGISTER CO. Nov. 1, 1956 [Nov. 3, 1955], No.33367/56. Class 106 (1). In electrical apparatus for transferring coded data unit(s) each comprising one or more digits, from a record member to predetermined locations in a multi-word storage register (J) associated with a digital computer, coded control data for each data unit, indicative of the number of digits and the required location in the multi-word register, is shifted along a control register to control the transfer of the data unit digit by digit from the record member to an intermediate register (E) and the subsequent transfer of the complete unit from the intermediate register to the multi-word register. General.-The apparatus described reads in data, e.g. relating to retail sales transactions, from a perforated tape 184, Fig. 1, and records it in rearranged sequence in recirculating buffer register J, Figs. 1 and 9, formed by a track on the magnetic drum memory of a computer similar to that described in Specification 770,952. The drum 101 has a clock pulse channel 108 controlling binary and octal digit-period-defining counting circuits 117, an arc address channel 109 containing 64 successive octal numbers 0- 77 defining the addresses of words stored in main memory channels 118, and channels forming with the arithmetic unit; 114 one-word recirculating registers E, F, G, H, as well as the 8-word register J. The 42-binary-digit word may comprise decimal digits (e.g. obtained from the tape) each occupying 4 binary positions, or octal digits (e.g. defining addresses) each occupying 3 binary positions. The unit 114 comprises a logical network (details not shown) associated with bi-stable hard valve trigger circuits (called " flip-flops") such as E1- E5 included in register E, and the operating sequence for carrying out a computer command, set up in register H, is determined, by programme counter 115 controlled by flip-flop K1 so as either to step on to the next value, or to skip or stay in the same condition, at the end of a word period. Only the operations for the " read-in " command are described in detail. Tape and reader.-In the paper tape 184, Fig. 7, a decimal digit or other symbol is recorded in each row by holes in 2 out of 6 column positions in line with a timing hole in a seventh column. The data is arranged in frames separated by "run-in " symbol and each starting with a frame symbol. Each frame is divided into segments each identified by a decimal digit SI, the first of which also identifies the frame (FI), and each comprising one or more data units in the form of decimal numbers. The data is read row by row by photo-cells 187, Fig. 1, and converted by 188 into a 4-binary-digit code on lines T1-T4 together with timing signals on line 180, the tape drive being controlled by computer signals on line 182. Computer control of read-in.-The " read-in " command in H includes a single base address (in octal form) which is combined with the FI digit from the tape to call up from the main memory a 3-word control pattern. This pattern is entered in H, G and F which are combined by logical circuitry (including flip-flops L1-L4, A5-A8) into a single register with decimal digit shift, and comprises a digit SI for each possible segment in the frame, followed by a group of decimal digits P, N, J, Fig. 8, for each data unit in the segment, whereby each unit may be entered independently into any desired position in the register J. Digit J indicates the word position or arc address (0-7), P the position of the first digit within the word, and N the number of digits. The third word ends with an address which may call up a further group of 3 words of the control pattern, or the next comman, from the main memory. Read-in sequence.-Before a segment is read in, an identifying digit SI in the control pattern will have been shifted into the first position in H (O 12  P 0  to O 13  P 0 , Fig. 8). This digit and the digit SI from the tape are set up in flip-flops A9-A12 and A1-A4 respectively and compared. If they agree, the control pattern is shifted two decimal digit steps to bring digit N for the first data unit into the first position, digit P being entered in A9-A12. The next digit is sensed from the tape and flip-flops A5, A6 and A9-A12 are connected as counters, whereby " 1 " is subtracted from P every decimal digit period (4 binary periods); when P is reduced to zero the sensed tape digits set up on A1-A4 is stepped into register E, but the subtractive count continues whereby at the end of a word period P registers " 1 " more than at the beginning. During the word period, digit N is reduced by " 1," and the above sequence is repeated until N is reduced to zero, i.e. until all the digits of a data unit have been entered into consecutive decimal digit positions in E. A further shift of the control pattern brings digit J into the operative first position in H; when the required arc or word position in J, specified by this digit, has been found, the data unit in E is transferred thereto. This process is repeated for subsequent data units in a segment ; for the last unit in a segment, a " 1 " (ESI, Fig. 8) is entered in the normally vacant highest binary position for digit J which causes the computer to step to the read-in sequence for the next segment. If the digit SI in the control pattern relates to a segment omitted from the tape so that the comparison indicates disagreement, the corresponding part of the control pattern is eliminated by repeated shift. When the end of the 3 words of a control pattern is reached (zeros in O 0-7 , of H), if the address indicates that additional words of the pattern are to be called up (" 1 "in top address position AI), these further words are entered into the combined register H, G, F and the sequence is continued. If the address is the control number for a new command, this number is shifted from position O 11-8  to O 7-4 , by employing the G-register and by-passing flip-flops G2-G5, and the programme count is returned to " rest " unless the next digit on the tape is not a frame or run-in symbol when an error indication will be printed. Example -Fig. 9 shows how the frame of data shown on the tape in Fig. 7 will be positioned in register J under control of the 6-word pattern shown in Fig. 8. The first 3 words of the pattern are obtained from main memory addresses 1513 to 1515, the third word containing the address 1521 for the second group of 3 words. The frame may relate to one cash register transaction in a retail store, the fourth segment, for example, giving data relating to the sales clerks, and the fifth segment data entered from a coded price tag attached to the merchandise sold.