Patent GB-745907-A (GB)
Title: Improvements in or relating to electronic apparatus for translating a number from a first to a second radix of notation
Inventor: BIRD RAYMOND
IPC: H03M7/08
Filed: 1952-11-04
Abstract: 745,907. Digital electric calculating-apparatus. BRITISH TABULATING MACHINE CO., Ltd. Oct. 2, 1953 [Nov. 4, 1952], No. 27727/52. Class 106 (1). In electronic apparatus for translating a number from a first to a second radix of notation, the number being represented in the first radix by an electrical signal or signals, a limited number of stored signals representing the equivalents in one radix of values in the other are read out sequentially and used selectively in forming the translated number. In the binary-to-decimal translator shown in Fig. 1, the equivalents of successive powers of two are stored serially around a single track of a magnetic drum in coded decimal form, each decimal digit being expressed as a combination of binary digits 1, 2, 4, 8. These equivalents are read by a head 2 and passed through a gating and amplifying circuit 3 controlled by clock pulses read by a head 5 from a second track on the drum. The binary number to be translated is stored in a shifting register 4 which receives stepping pulses from a frequency-dividing counter 12 controlled by the clock pulses, whereby each binary digit, if " 1," controls the passage of the equivalent value through a gate 7 to an accumulator which comprises an adding circuit 8, e.g. as described in Specification 678,427, and a result-storing shifting register 9. In another form of translator, Fig. 2, the drum 13 stores the equivalents in binary form of the values 1, 2, 4, 8, 10, 20, 40, 80, &c. The largest equivalent is read out first and subtracted in circuit 15, which may be as described in Specification 738,269, from the binary number to be translated obtained from shifting register 16, the difference being stored in shifting register 20. According to whether this difference is positive or negative, a gate 21 or 22 is opened to allow a pulse on line 23 to enter one or zero into a result-storing shifting register 24, and to set a bi-stable double triode trigger circuit 19 in the condition to open gate 18 or 17. The latter gates respectively permit read-out of the contents of registers 20, 16 'to the subtracting circuit, and also to the input of register 16. Thus if the difference is positive it replaces the original number and has the next equivalent subtracted therefrom, the process being continued until the complete translated number has been built up in register 24 in the binary-coded decimal form with the most significant digit on the right. A control circuit (Fig. 5, not shown) is described for this arrangement. According to further modifications, a comparing circuit, e.g. as described in Specification 738,294, is used to allow subtraction only if the difference will be positive, the equivalents being passed through a delay circuit such as an electrical or mercury delay line or a shifting register before they reach the subtracting circuit, or the differences between successive equivalents are stored on a separate drum track, these differences and the equivalents being selectively read out to an add/subtract circuit. Circuit details of various components are given. According to the Provisional Specification, the binary coded decimal number obtained may be read out in the form of timed impulses which operate printing or punching magnets (one for each decimal digit). Reference is made also to scales of three, twelve and twenty.