Patent GB-835243-A (GB)
Title: Electronic computer system
IPC: G05F1/577
Filed: 1956-03-02
Abstract: 835,243. Electronic computers. BURROUGHS CORPORATION. March 2, 1956 [March 4, 1955], No. 6693/56. Class 106 (1). An electronic digital computer, having a pinboard programming device and means to enable individual instructions to be set up manually, receives data from switches set to represent the digits of a number, and comprises an electronic counter which, for each digit in turn, is pre-set in accordance with the digit and then counted out to enter the digit into arithmetic circuits. The switches are set in the arrangement described by a multi-order full-keyboard printing-machine. The computer described has a magnetic drum data store and two additional tracks on the drum serving as A and B registers. The A register incorporates an adder and forms an accumulator, while the B register is used in multiplication and division operations to store the multiplicand and divisor respectively. The computer operates with words of twelve decimal digits plus a sign digit, the decimal digits being presented serially but each being represented by a number of bit pulses equal to the decimal digit. The digits are separated by vacant bits. A negative sign is represented by nine bit pulses in the sign digit period and a positive sign by the absence of pulses. Output as well as input is provided by the printing-machine which is cyclically operating and has a mechanical programme unit to determine the column- and line-spacing movements of the paper-carriage. It is generally similar to the machine described in Specification 709,181. Certain functions of this machine may be selected under the control of the computer by means of solenoids as described in Specification 782,253. It is suggested that an auxiliary tape input device may be added. The computer itself is programmed by means of visible pin-boards similar to those described in Specification 797,457, and operates with single-address instructions. Control functions are performed, in general, by networks of diode-gate logical circuits. As these circuits are controlled by, and themselves control, various flip-flops forming counters and other control units, the flipflops produce their output signals resulting from a change in state over a delay circuit. The complete computer is housed in a desk, the rear portion of which contains the electronic circuitry and is hinged to the front portion for easy access.. Power is switched on by a switch 125, Fig. 7, the supplies in the computer becoming effective in stages under the control of time-delay relays. " Wait " and " Ready " indicators 127, 129 are provided. A voltage failure at any one of several points in the circuits will disconnect the entire supply. An alarm circuit, Fig. 38, is operated as described below if incorrect conditions arise in addition or subtraction, division, the print check operation or during entry into the B register. Timing circuits.-The magnetic drum has three timing tracks. The basic timing track bears 1300 pulses corresponding to the 1300 bits stored on a data track. These are processed through tuned amplifiers and the two halves of the consequent sine wave are shaped to form interspersed sets of t and u timing pulses. Drum writing pulses v, slightly leading the t timing pulses, and bit pulses T and U corresponding with, but of longer duration than, the timing pulses t and u are also derived. A further timing track bears 130 pairs of D and E pulses corresponding to the 130 digits on a data track, while the third timing track bears ten W (word) pulses, a single B pulse and a single C pulse. The signals obtained from these tracks are similarly processed and by means of gating circuits, Fig. 10 (not shown), associated also with the T and U bit pulses, digit pulses D and E are distinguished (occurring at T and U times respectively) and the word pulses W and single B and C pulses are distinguished. Moreover, for counting-out purposes, digit groups of nine T and U counting pulses are obtained from the digit groups of ten T and U bit pulses. Digit distributer.-To distinguish the sign digit period and least significant digit period in each word period, flip-flops DD1 and DD2, Fig. 21, are controlled by digit pulses D and word pulses W so that DD1 is in reset condition during the sign digit period DPO only and DD2 is in that condition during both DPO and DP1, the least significant digit period. Digit scanner.-Four flip-flops SC1-SC4, Fig. 34a, are associated with logical circuitry, so as to assume thirteen different states in sequence in response to digit pulses. Thirteen leads SD0- SD12 forming the output of a diode matrix connected to the flip-flops signal the different states. Counters.-In addition to the digit scanner which is a binary-coded counter with a radix of thirteen, radix-10 counters are used in the adder and for general purposes. These each comprise four flip-flops 25, Fig. 25 (not shown), each having changeover, set and reset inputs, and interconnected as in Fig. 24. The counter may be pre-set by means of leads N, F, D, B (generally to a complement) and produces a signal when a count of nine is reached. The " nine " signal and a negated signal obtained therefrom are used as shown to determine the counting sequence. State counter.-In carrying out an instruction, the computer passes through several states as determined by the state " counter." This comprises three flip-flops which are independently set and reset under the control of logical circuitry, Figs. 51-54 (not shown), in turn controlled by the timing pulses and instructions. The eight states (0-7) which may be assumed (not necessarily in sequence) are represented by signals on the output leads of a diode matrix associated with the flip-flops. In some of the Figures, these signals are shown by the corresponding digits 0-7. Programming and manual control arrangements.-The sequence of operations to be performed is set up by the insertion of pins in five pin-boards 46, each, Fig. 6, having four sections 81, 87, 89, 83 and sixteen rows, each corresponding to a step in the sequence. The nature of the operation is specified in the first section 81 and a single storage location by tens and units digits a, b set in the sections 87, 89. The last section is used in connection with the Z switch described below. When a switch 109 in a manual control panel 48, Fig. 7, is set to " Manual," the computer is controlled in accordance with the instruction set on the switches 81M, 87M, 89M. During automatic operation, if a pin is inserted in an X position in the section 87 of a pin-board or in a Y position of the section 89, the corresponding digit of the storage location will be determined by the setting of the corresponding X or Y switch 115,117. The pin-board and step are selected by multi-bank stepping switches, Fig. 35 (not shown), advanced by solenoids under thyratron control. The thyratrons are fired under the control, through diode gate circuits, of the state counter, timing pulses and the switches themselves. One switch selects the pin-board and each pin-board is associated with a corresponding switch to select the step. The latter switches are advanced individually according to the pin-board in use at any instance and consequently the sequence of operations determined by one pin-board may be taken up again at a point previously reached. These switches control neons to indicate the pin-board and step reached. A thyratron-controlled interrupter relay prevents current flow through the contacts of the stepping switches while they are being advanced. By pinning a suitable instruction in the third pin-board section 89, with or without a print instruction, the computer may be halted. This results from the re-setting of a flip-flop which prevents stepping to the next instruction and also controls an indicating lamp 111, Fig. 7. This flip-flop is also re-set during any operation in which a switch 113 is in a " Single step " position and on operation of the alarm circuit, Fig. 38. Five push-buttons 123 enable an operator to initiate computer operation at any one of the five pin-boards. Programming; transfer operations.-Normally, the instructions are taken in sequence but provision is made for both conditional and unconditional transfer operations by which control is switched to a pin-board and step defined by the a and b digits of the transfer instruction. For use in carrying out these instructions, two additional stepping switches are provided to remember the a and b digits while the other switches are being stepped accordingly. The unconditional transfer operation is as follows. During state 1, the C pulse (defining an angular position of the drum opposite that defined by the B pulses) operates a special thyratroncontrolled relay to register the fact that a transfer operation is taking place and also switches the state counter to state 2. C pulses then step the first additional switch until it is set according to a, the intermediate B pulses testing for correspondence. The state counter is then switched to state 3, in which B pulses step the second additional switch until it is set according to b as tested by C pulses, whereupon the state counter is switched to state 4. The switch which selects the pin-board is then stepped by C pulses into correspondence with the first additional switch so as to select the pin-board represented by a and state 5 is assumed in which B pulses step the switch of the selected pin-board into correspondence with the second additional switch so as to select step b. A further thyratron relay is then operated to extinguish the previously-fired special thyratron and cause the state counter to assume state 0 in which the selected instruction is performed. In a conditional transfer operation, during state 1, the accumulator (see below) is tested and if it registers zero, the sign flip-flop AD1, if set, is reset to register a positive sign. The C pulse then tests the flip-flop AD