Patent GB-1188990-A (GB)
Title: Data Reduction Computer for Radiation Counting Equipment
IPC: G06F7/52
Filed: 1967-09-01
Abstract: 1,188,990. Electronic calculators. BECKMAN INSTRUMENTS Inc. 1 Sept., 1967 [10 Oct., 1966], No. 39999/67. Heading G4A. A computer has means for adding two numbers coded in a coded decimal binary system and stored in two registers in a number of different alignments. In an arrangement for adding, subtracting or dividing the contents of two registers, a first register 10 comprises a plurality of pulse counting decades 12-17 with carry lines 23 and a second register 11 comprises a plurality of pulse counting decades 18-22 with the carry leads temporarily disconnected. Each decade preferably operates in the excess-three BCD code which is self-complementing. Addition.-Trains of 10 pulses each from a source 32 are passed by way of a switch 28 to each of the decades 18-22 in turn and, as each decade emits a carry signal, a detector 30 is energized to open a gate 29 to allow the remainder of the respective train of pulses to pass to the corresponding decade 12-17 by way of a switch 28 which operates in unison with the switch 27. The decades of the register 11 are thus returned to their original states whilst the register 10 is incremented by the contents of the register 10. The fixed contacts of switch 27 may be connected to any group of adjacent decades in the register 10 whereby the alignment of the registers 10 and 11 may be changed. Subtraction.-The contents of register 10 may be complemented by a signal on a line 31 and recomplemented after the contents of register 11 have been added, as described above. Division.-At each stage (the sixth is illustrated in Fig. 4) the contents of register 11 (the divisor) are added into the complemented contents of register 10 (the dividend) until overflow to a detector 35 occurs, whereupon, to restore the dividend register to its immediately preceding state the register 10 is recomplemented, register 11 added thereto and register 10 complemented again. The connections between the fixed contacts of the switch 27 and the decades 12-17 are then shifted each to the next adjacent decade of lower significance and the process repeated. For each time that the divisor in register 11 is added to the complemented dividend in register 10 without overflow occurring, one is added into a quotient counter corresponding to that stage of the division process. A single quotient counter may be provided if the result of each stage is printed before starting on the next stage. Initially the decade 18 would be aligned with the decade 17 by way of contact 1 of switch 27 and fixed contacts 2-5 of this switch would all be connected to the detector 35. When, after six stages of the division, decade 18 becomes aligned with decade 12, the division process may be continued indefinitely if successive decades (starting with 17) are reconnected one-by-one to effectively constitute lower order decades on a cyclic end-around transfer basis. A scale of 10 counter for metering out trains of 10 pulses (Fig. 5E, not shown) a scale of 5 counter for controlling the stepping of the movable contacts of the switches 27, 28 (Fig. 5C, not shown) and a further counter having a scale depending on how many division stages (i.e. quotient places) are described in detail together with other control elements in Figs. 5A-G (not shown). The registers 10 and 11 may comprise a counter for counting pulses from a radiation detector and a register for counting timing pulses respectively, the quotient thus representing for example counts per minute.