Patent GB-742470-A (GB)
Title: Improvements in or relating to electronic digital computing machines
Inventor: THOMAS GRAHAM ISAAC
IPC: G11C11/23
Filed: 1950-08-18
Abstract: 742,470. Digital electric calculating-apparatus; electric digital-data-storage apparatus. NATIONAL RESEARCH DEVELOPMENT CORPORATION. Aug. 13, 1951 [Aug. 18, 1950], No. 20540/50. Class 106 (1). An electronic digital computer comprises a main data store and control means arranged for operation in parallel mode, computing apparatus arranged for operation in series mode, and signal mode converting means for converting parallel mode output signals from the store to serial mode input signals for the computing apparatus and vice versa. General arrangement. The computing machine shown comprises a main store MS, Fig. 1a, comprising twenty similar units T0-T19, e.g. as described in Specification 657,591 or 705,474, each comprising a C.R.T. 10, pick-up electrode 11, read unit 13 and write unit 15. Each word comprises twenty binary digits, one of which is stored on each C.R.T. screen which has a capacity of thirty lines each of 32 digits. Words are selected by time base unit MSTB, described below, which applies the same X- and Y- deflecting voltages over leads 19, 20 to all the C.R.T's. Input to and output from MS are effected via staticisor MSTR comprising bistable trigger circuits STC0-STC19, e.g. of the Eccles-Jordan type, corresponding to units T0-T19 respectively. The triggers STC are connected to form a counter so that they may be used for adding " 1 " to the " control instructions " as described below. In an instruction word, positions 0-9 contain a main store address and set MSTB, and positions 10-19 determine the function to be performed and set function staticisor triggers FTC10- FTC19, Fig. 1b. The computing section CMPR, the series-mode input to and output from which is controlled by gates G6, G7, comprises an accumulator A having a single-line C.R.T. 31 and a series-mode adding circuit 35, and other elements, e.g. for performing multiplication such as those described in Specifications 705,476, 731,341 and 742,522. The machine may also include a subsidiary magnetic store. The basic waveforms shown in Fig. 2, (a)-(d), of which the dash waveform, Fig. 2, (a), defines the 10NS digit intervals, are generated by unit WFGU. A complete operative cycle or " bar," Fig. 2, comprises five "action " beats A1-A5 (in which the store MS is involved) and six " quiescent " beats Q1-Q6, each comprising one digit interval, and a further " scanning " beat S comprising twenty digit intervals S0-S19 during which conversion of a number to or from serial form takes place through gates GB0-GB19 or GD0-GD19 controlled by P-pulses P0-P19, see Fig. 2, (e)-(h), generated during each beat S by am arrangement similar to that described in Specification 705,477, [Group XL (b)]. The beats are defined by waveforms, Fig. 2, (i)-(t), obtained from a stepping arrangement (Fig. 4, not shown), including series-connected trigger circuits, reset by the inverted dash waveform, Fig. 2, (b), and a pulse dividing circuit, e.g. of the phantastron type. The trigger initiating the first beat Q1 is actuated by a prepulse, Fig. 2, (u), generated by circuits prepared during the last beat A5 of the previous bar or by manual control means. Time base unit. The deflecting voltages on leads 19, 20, Figs. 1a and 6, from the anodes of summation valves Vs1, Vs2, are each controlled by five bi-stable trigger circuits TB0-TB4 or TB5-TB9, thus giving thirty-two possible combinations. The triggers are set by potentials applied either over leads 21, 22 from staticisor triggers STC0-STC9 or over leads 24, 25 from counter circuits CWG, which are operative during the beats S which involve outward transfer from the main store MS (gate G6, Fig. 1b, being open) to regenerate systematically all the 32X32 storage locations on the C.R.T. screens. The anode outputs of valves such as V2 of triggers TB are applied to the control grids of valves Vs through resistances such as RLO of such values that, e.g. the switching over of TBO, 1, 2, 3, 4 will change the potential on lead 19 by 1, 2, 4, 8, 16 unit steps respectively. The triggers can be reset to the condition in which they select store address (O, O) by a pulse on lead 23. In a modification (Fig. 7, not shown), the triggers are replaced by grid-controlled amplifier valves. Operating sequence. At the beginning of first beat Q1 of a bar, the prepulse, Fig. 2, (u), is applied to leads 23, 28 and 39 to reset the time base unit MSTB, staticisor MSTR and function staticisor FTC10-FTC19 respectively. During the following beat A1, gates GA0-GA19 open to pass the previously used " control " instruction " (C.I.), stored at address (O, 0), to MSTR, and during Q2, " 1 " is added to form the new C.I. by a dash pulse applied through gate G5 to staticisor trigger STCO. During A2, Q3, Q4, gates GE0-GE19, GC0-GC9, G4 cause the new C.I. respectively to be written into MS, to set MSTB to the address of the " present instruction (P.I.), and to be cleared from MSTR. The P.I. is passed to MSTR during A3, via gates GA0-GA19, and during the following beat Q5, gate G29, Fig. 6, passes a reset, inverted dash pulse to MSTB, and gates GC0-GC19 cause the P.I. to set MSTB to another main store address and triggers FTC10-FTC19 to the function to be performed, MSTR being cleared during the following beat Q6. If the function involves an outward transfer from MS, gate G2 is operative during beat A4 to open gates GA0-GA19 to pass the number at the selected address to MSTR, and during the scanning beat S the number is translated into serial form by gates GB0-GB19 and passed through gate G6 to the computing section GMPR; at the same time, MSTB is reset through gates G30, G29 Fig. 6, and regeneration of the store is effected under control of CWG. For inward transfer operations, however, beat A4 is inactive, and during beat S, a series-mode number is passed from CMPR through gate G7 to gates GD0- GD19 which translate it into parallel form and apply it to MSTR; during the final beat A5, gate G9 is then operative to open gates GE0- GE19 to write the number into the store MS. A modified bar is described in the Provisional Specification in which the quiescent beats are reduced to three. Specifications 682,156, 692,853, 705,479 and 707,634 also are referred to. The Provisional Specification also refers to Specification 645,691.