Patent GB-742522-A (GB)
Title: Improvements in or relating to electronic digital computing machines
Inventor: WILLIAMS FREDERIC CALLAND
IPC: G06F1/04
Filed: 1950-05-18
Abstract: 742,522. Digital electric calculating-apparatus; electric digital-data-storage apparatus. NATIONAL RESEARCH DEVELOPMENT CORPORATION. May 18, 1951 [May 18, 1950], No. 12499/50. Class 106 (1). In an electronic digital computer including a main data store capable of registering data words each at a unique address, electric-signalcontrolled address selection means for rendering immediately accessible any required one of address locations in the store, a subsidiary data store arranged for operation at a digit signalling speed synchronized with that of the main store and including a movable recording medium capable of accommodating data words at defined sequentially accessible positions of an elongated track, and means for effecting direct transfer of data words in either direction between the main and subsidiary stores, the subsidiary store provides an address signal indicative of the particular data word storage position therein which is currently accessible, which signal is used to control the main store address selection means during a transfer operation. General arrangement. The machine illustrated in Fig. 1 is generally similar to that described in Specification 731,341 employing C.R.T. binary digital stores, e.g. as described in Specifications 657,591 and 705,474, and a scanning system of normally alternate scan and action beats similar to that described in Specification 682,156. Each beat comprises 24 digit periods, Fig. 2, and the basic dash, dot and black-out waveforms and p-pulses p<SP>0</SP>-p<SP>23</SP> are produced in generator WGU as are also beatdefining and other controlling waveforms as described below. The main store S comprises 16 C.R.T.'s, each of which has two columns or " pages " of 32 lines each containing a 20-digit number or instruction word, which columns are scanned alternately by applying a shift voltage to the X time-base circuit (not shown). A twoline control unit C, Figs. 1 and 20, described below, registers the " control instruction " CI and " present instruction " PI which are staticized in unit STU, and present instructions may be modified by an eight-line B-tube unit BU, Fig. 1. The accumulator A, which is generally similar to that described in Specifications 734,072 and 734,075, including parallel computing circuit paths, has a C.R.T. with 4 lines to accommodate an 80-digit word, and is associated with a multiplier M, e.g. as described in Specification 712,172. A subsidiary magnetic drum store W is provided with means for effecting block transference of data between the main and subsidiary stores generally as described in Specification 737,864, but with the address selection in the main store controlled by one of the tracks on the drum as described below. The normal instruction word, Fig. 2 (j), comprises six l digits sent to staticisor sections l0-l5, Fig. 23b, for selecting a column and line of a main store tube by controlling the Y-scan generator (not shown) during action beats; four e digits sent to sections e6-e9 for selecting the tube; three b digits sent to sections b10- b12, Fig. 21, for selecting a line of the B-tube TB5, and seven function digits f sent to sections f13-f19, Fig. 20. A data transfer or " magnetic " instruction, Fig. 2 (k), comprises eight T digits sent to staticisor sections T0-T7, Fig. 23a, for selecting one of 256 tracks on the magnetic drum MDR, five function digits F sent to sections MF10-MF14 and four tube-selecting digits E sent to sections E16-E19 connected to sections e6-e9, Fig. 23b, as shown. The machine also includes a unit MSD, Figs. 1 and 22, for finding the sum of the digits and the most significant digit of a number. Reference is made to the use of punched cards or perforated tape for the input and output of the machine. Circuit symbols. Figs. 5b-8b show the circuits represented by the symbols of Figs. 5a- 8a respectively in the diagrammatic drawings. Figs. 5a and 5b represent an " and " diode gate, operating potentials (negative from a resting level of earth) applied simultaneously to inputs 10-14 producing a negative potential on output 15. Similarly, an " or " diode gate is illustrated in Figs. 6a and 6b, and Fig. 7a shows the symbol used for an R.C. differentiating circuit, Fig. 7b. In the normal or " off " condition of the bi-stable trigger circuit illustrated in Figs. 8a and 8b, valve V1 is conducting and an operative negative potential exists on lead 20. The circuit may be triggered to the " on " condition (operative potential on lead 19) by a negative pulse on lead 16, triggered " off " by a reset pulse on lead 17, and triggered either way by a pulse on lead 18. Generation of controlling waveforms. The means for generating the basic waveforms shown in Fig. 2 (a)-(h), and for the manual or automatic production of prepulses, Fig. 3 (a), are generally as described in Specification 731,341. The single-operation bar, although normally of four beats, can be extended to five (additional beat A3) or seven beats for accommodating 40- or 80-digit words. In the latter case, the last two beats S3, B4 overlap the first two beats S1, A1 of the next bar. The beat-defining waveforms, Fig. 3 (b)-(o), are produced by means, forming the subject-matter of the invention of Specification 742,524, comprising series-connected trigger circuits F3-F9, Fig. 12, of which F7-F9 are operated through a gate G5 opened only for five or seven beat rhythms. The first circuit F3 is triggered by the prepulses on lead 101, and all the triggers are reset by the differentiated black-out waveform. By combining the waveforms A1, A2, A3 with a data transfer action waveform TAWF (not shown) the action waveform SAWF and its inverse are produced, Fig. 3 (p) and (q). Action waveform AAWF is similarly produced by combining A2, A3, S3, B4. The counter waveforms C0-C6 (not all shown), used for controlling regeneration of the C.R.T.'s, are produced by trigger circuits connected to form a binary counter (not shown), the gated input being such that the waveforms depend on the machine operation as illustrated by Fig. 4 (a)-(c). The production of waveforms J, G, U, Fig. 4 (j)-(l), during data transfer is described below. Control unit; input and output gates. This is generally similar to the unit described in Specification 731,341 and comprises a tube TB4 and a Y-plate generator LLC, Fig. 20, controlled through gates as shown, so as normally to produce the waveform of Fig. 4 (g), the C.I. line being scanned during beats S1, A2 and the P.I. line during A1, S2. The regeneration circuit includes the usual read unit 58 to which erase potentials are applied as indicated, and an adder 59 to which " 1 " (pulse p<SP>0</SP>) is normally sent at the beginning of each bar, to be added to the C.I., via gate G52, opened by waveform S1, and " or " gate G43. The gate G52 is closed during manual operation by switch S6, instructions then being set up by switches S7 which supply appropriate potentials MI0-MI19 to the staticisor gates such as G68. The input gate G43 also receives the instruction-modifying words from the B-tube via lead 125 and gate G42 controlled by trigger F18, and words from the main store via lead 116 and gate G37 opened during every beat A1 and during a beat A2 in which the instruction to be obeyed is an unconditioned transfer from store to control unit (S, C) or a transfer conditional on a successful sign test of a number in the accumulator (test A, lead 110), or the B-tube (test B, lead 111). The B-test arrangement comprises a circuit F140, Fig. 21, which is triggered whenever a B-number is used by pulse p<SP>10</SP> through gate G48, thus applying a gate-opening potential on lead 111 to gate G37, which potential is removed, through gate G49, if the number has a " 1 " in the signindicating position p<SP>19</SP> (test unsuccessful). The control unit output, obliterated by switch S8 during manual operation, is fed through pulseshaping gate 61 to the staticisor sections via gate G66, Fig. 20, lead 112 and gate G77, Fig. 23b, and lead 113 and gate G128, Fig. 21. The operation of the control unit as a counter during the data transfer operation is described below. B-tube unit. The Y-plate voltage generator BYWG for tube TB5, Fig. 21, is controlled by staticisor sections b10-b12, directly during a beat A2 through gates G140, and through " shuffle " or delay circuits SHC and gates G141 during a beat S2, the circuits SHC being set from the staticisor sections via gates G142 during the previous beat A1. The regenerating circuit includes an adding or, as shown, a subtracting unit AMU whereby any B-number may be modified by or replaced by numbers from the main store on lead 103. The B-output, in addition to being sent to the control unit over lead 125 may be sent to the main store via gate G15 and lead 105. This B-tube unit forms the subjectmatter of the invention of Specification 742,525. Unit MSD. This forms the subject-matter of Specification 742,526 and comprises triggers Z0-Z5, Fig. 22, connected to form a binary counter. To find the most significant digit (2m) of a number (instruction MS), 24 is first set up on the counter by triggering Z3, Z4 and resetting Z0, Z1, Z2, Z5 by pulse p‹ sent through gates G173, G172 at the beginning of beat A2. During the beats A2, A3, dash pulses, Fig. 2 (a), are then added into the counter through gate G174 and the counter is reset to 24 by every " 1 " digit in the number on lead 104 also sent through gate G172. Thus, the counter is set at the end of A3 to (39 - m)+24=63 - m. The complement or inverse of the counter setting, which is dynamicised and applied to the accumulator via lead 107 and gates G175, G176 during beat S3, therefore equals 20 - (63 - m) - 1 =m. To find the sum of the digits of a number (instruction +S), the triggers are reset at the beginning of beat A2 through gate G 144, and the number on lead 104 is applied to the counter through gate G145 so that the " 1 " digits are counted up.