Patent GB-574405-A (GB)
Title: Improvements in or relating to adding and subtracting machines
IPC: G06F7/42
Filed: 1943-10-05
Abstract: 574,405. Calculating - apparatus. BRITISH TABULATING MACHINE CO., Ltd. Oct. 5, 1943, No. 16327. Convention date, Oct. 10, 1942. [Class 106 (i)] An electrically-operated machine under the control of keys for adding and subtracting by complementary addition comprises a set of four accumulating relays and related contacts for each denominational order upon which a number set up is represented in the binary system of notation, a group of four entering relays with related contacts for each order, and a second group of connections extending between adjacent orders to complete a single path through the accumulating relays whereby the setting is changed to represent the sum of the numbers entered. The four accumulating relays have each a value assigned thereto in accordance with the first four terms of the binary progression, viz. 1, 2, 4 and 8. For subtraction, amounts are set up in the form of complements of 15 and where the balance is negative the accumulator relays are set to represent the complement of the balance. In each order there is provided a numeral representing lamp constituting a read-out device to indicate the true value, the algebraic sign being indicated on a plus or minus lamp.' Keyboard. A portion of one bank of keys is shown in Fig. 1. The keys 1 are slidably mounted in a frame 2 and co-operate with a latch bar 3 to hold a key in depressed position. The zero key serves as a clearing key, while the other keys on depression control the operation of sets of contacts a, b and c. The several contacts associated with the keys are shown in Fig. 4 which represents diagrammatically the hundreds denomination of a machine for handling decimal amounts ; the units and tens denominations are similar. The contacts a, band c are arranged to convert the digit entered into a binary equivalent directly or to form its complement. In addition to the digit keys there are three operation keys 109, 110 and 111, Fig. 4, which are depressed when an amount is to be added, subtracted or the machine reset respectively. Relays. Each accumulator relay comprises a magnet A, Figs. 2 and 3, with a plurality of windings mounted on a frame 14 to which is pivoted the armature 8, a bell-crank lever 10 and a T-shaped lever 15. A spring 17, attached at one end to the lever 15, is connected to a pin 19 on an arm 13 pivoted to the armature 8. The free end of the arm 13 co-operates with the hooked ends 20, 21 of the lever 15. The lower arm of the bellcrank lever 10 co-operates with a set of contacts, three of which are shown designated a, band c. When a magnet A is energized, the arm 13 is moved to a preparatory position shown. in dotted lines, Fig. 2, and upon de-energization the arm 13 is moved to operate the bell-crank lever and shift the contacts as shown in Fig. 3. The movement of the bell-crank lever 10 is effected by the co-operation therewith of pins 22, 24 on the lever 15. The entering relays are magnets of the type which shift their related contacts upon energization and enable the contacts to return to normal upon de-energization. Circuit arrangements. The operation keys control contacts 109a, 110a and 111a and the plus key 109 also operates bellcranks 112, 113 to displace rods 114, 115 controlling various contacts. The accumulator relays are designated A1, A2, A4 and A8 and the entering relays are marked R1, R2, R4 and R8. The indicating circuit includes the digit representing lamp 25 and the negative and position sign lamps 26, 27. Common to all denominations is a set of control relay magnets SA, SC and ST. The relay SA is of the slow-acting type, relay SC is of the same type as the accumulator relays and relay ST is similar to the entering relays. In adding operations, the first number is set on the keys in the various denominations and the key 109 is depressed to complete a circuit through the contacts 109a to energize the appropriate relays R. The slow-acting relay SA then operates to close its contacts a and a circuit is completed to energize the appropriate accumulator relays A. The key 109 is then released and opens its circuits to de-energize the relays R and A, but the contacts of the A relays will remain set. This setting will be indicated on the lamps 25, 27. The second amount is then entered and the key 109 again depressed. The appropriate relays R will be energized and then the relay SA will operate to complete a single circuit through the several denominations to energize the appropriate relays A which when the key 109 is released will shift their contacts to the set or unset position in accordance with the sum of the amounts entered and this amount 'will be shown on the lamps 25. The circuit connections are so arranged as to take into account automatically the necessary carry-over and whatever correctives are called for in handling the decimal and binary notations. For subtraction operations, the amount to be subtracted is set up on the keys and the minus key 110 is depressed to close contacts 110a, and as the contacts a, b, c and d associated with the rod 114 remain in the position shown in Fig. 4 the R relays will be energized in accordance with the complement of the digit set in each order and the relay ST will be energized. or not energized depending on the relative values of the amounts on the relays A and R. Depression of the clearing key 111 closes contacts 111a to complete a circuit to unset the relays A and to put the zero lamps A into circuit. In a modification, Fig. 7, an arrangement of accumulating circuits is shown by means of .which each order (one only of which is shown) may be adjusted to handle numbers in any system of notation with radix up to 16. The key bank includes sixteen keys 1, sixteen indicator lamps 25, and appropriate contacts for the relays A and R. Four additional relay magnets C1, C2, C4 and C8 are provided with groups of contacts and these are controlled by cams 301, 302, 304 and 308 mounted on a common shaft 309 settable by a handle and pointer 310 to select the radix. Examples of the use of the apparatus for computations involving decimal quantities and feet and inches are described in the Specification.