Patent GB-683601-A (GB)
Title: Improvements in or relating to calculating machines
Filed: 1947-03-31
Abstract: 683,601. Digital electric calculating-apparatus. BRITISH TABULATING MACHINE CO., Ltd. (Valtat, R.L.A.). March 25, 1948 [March 31, 1947], No. 8644/47. Class 106 (i). Apparatus for translating a number in binary notation into another notation with even radix or radices comprises, for the lowest denomination of the other notation, a circuit for adding together those digits in that denomination which appear in the powers of two represented in the binary number and expressed in the other notation, and, for each higher denomination, a circuit for adding together the digits in that higher denomination and for adding, simultaneously, the digits in all lower denominations, which determine the carry to that higher denomination, said carry being added to the digits in the higher denomination, whereby each digit of the translated number is determined independently of the determination of the other digits. The binary number is engered on a keyboard, for example, by depressing the keys of the binary denominations in which a " 1 " is present and thereby causing energization of corresponding relays [1]-[9], Figs. 2A, 2B and 2C. The relays [1]-[9] control contact arms 5 which along with their contacts are arranged as links in chain circuits, one circuit being provided for each decimal denomination necessary for the translation. The arrangement is such that in the " units " denomination, Fig. 2A, the path of an impulse through the chain at each link, i.e. at each row of contact arms, is determined (a) by the energization or non-energization of the associated relay and (b) by the exit point from the previous link. Each contact point may be considered as having a decimal value. The chain of Fig. 2A serves to add the " units " digits of all the powers of two represented in the binary number. The exit contact points from the last link are connected to lamps 7 which thus indicate the " units " decimal digit. The " tens " chain, Fig. 2B, is in two parts, a " carry " part and a " digit determining " part. The first three links of the " carry " part are, in this case, the same as the first three links of the " units " chain. In the " carry " part each link is arranged to provide for the addition of the " units "digit of the corresponding power of two and as many links are provided as are necessary to determine the " carries " which may have to be made from the " units " denomination to the " tens " denomination and thereby selecting the entry point 9 to the " digit determining " part of the chain. The points 9 may be considered as having decimal values of 0, 1, 2, 3, 4 in the " tens denomination. In the " digit determining part of the chain the " tens " digit of each power of two represented in the binary number and the " carry " from the " carry " part of the chain are summed. The exit points from the last link are again connected to lamps 7. The " hundreds " chain, Fig. 2C, is also divided into two parts, the first part serving to add the " units and tens " digits of each power of two represented in the binary number and so determine the " carry " that is the entry point 12 to the " digit determining" part of the " hundreds " chain. The latter part of the chain thus senses to add the " hundreds " digits and the " carry from the lower denominations. The exit points from the last link are again connected to lamps 7. With this arrangement each decimal digit is determined independently but simultaneously. In a modification, not shown, the chains are simplified by making some of the relays in the " units " chain and in the " carry " parts of the "tens" and " hundreds chains reverse acting, i.e. they move their associated contact arms in the opposite direction. Figs. 3A, 3B and 3C, not shown, illustrate chains for the conversion of a binary number into L.S.D. Electrically-controlled print magnets may be. substituted for the lamps 7. Each contact arm and its associated contacts may be replaced by two pentode valves 12 and 13 arranged in the circuit shown in Fig. 6. The control grids 16 are connected to a terminal A, the anode of the valve 13 is connected to a negative line through two resistances 18. The suppressor grid 19 of the valve 12 is connected to a point 20 and the suppressor grid of the valve 13 to a terminal D, the voltage of which may be altered to allow one or other of the valves 12, 13 to conduct.