Patent GB-780954-A (GB)
Title: Improvements in or relating to electric calculating machines
IPC: G06F7/44
Filed: 1954-07-30
Abstract: 780,954. Digital electric calculating-apparatus. EL-RE-MA SOC. ANON. PER LO SFRUTTAMENTO DI BREVETTI. July 30, 1954 [July 31, 1953], No. 22260/54. Class 106 (1). An electrical calculating machine, capable of performing addition and subtraction at least, comprises three groups A, B and R of switching elements for registering numbers used in the machine, and is so arranged that the switching elements of the A and B groups enable a number depending upon A and B to be transferred to the R group, and the switching elements of the R group enable a number depending upon R to be transferred to the B group. A desk-type relay operated full keyboard machine for performing the four rules is described. Mechanically settable keyboard controlled contacts of the type described in Specification 732,636, Group XXXVII], constituting the A group, and relay controlled contacts constituting the B group, together determine the path of current impulses through the control windings of a group of relays having contacts constituting the R group so that the contacts of the R group that are closed as a result of a current impulse represent on a coded decimal scale either the sum or the sum cyclically shifted one place in the direction of increasing significance of the two numbers represented by the closed contacts of the A and B groups, depending upon the direction of the current through the specified path, and the contacts of the R group determine the path of current impulses through the control windings of the B group so that depending upon the direction of the current through the path, the contacts that close will represent either the number represented by the R group or its nines complement, the relays used being of the polarized type described in Specification 751,478, [Group XXXVII]. Thus by controlling the direction of the current impulses it is possible to perform the four rules. Arithmetic unit. Each decimal denomination of the B group consists of 4 relays, Fig. 21, the first having one control winding B2, the second two windings 1B1, 2B1 (the arrow indicating a reverse winding), the third three windings 1B0, 2BO, 3BO and the fourth 3 windings 1Bu, 2Bu, 3Bu. Each relay has three conditions, for example the " u " relay can have all its contacts open, as shown, or contacts 1bu and 2bu closed, or contact 1bu* and 2bu<SP>*</SP> closed. The control windings for any one relay are only energized singly and the polarizing windings are so energized that after the current in the control winding has ceased the contacts thus closed remain closed. Each decimal digit is represented by the closure of selected contacts in a bi-quinary code, for example with contacts 1bu and 2bu closed and contacts 1b0* and 2bO<SP>*</SP> closed, the digit represented is 4. The R group of contacts are similar to the B group. Each decimal denomination of the A group consists of two slidable sets of contacts of the type described in Specification 732,636, the first set having 4 fixed contacts 1afu- 4afu, Fig. 19, and 3 movable contacts 1amu- 3amu, which can be positioned in one of two positions, and the second set having 10 fixed contacts 1af-10af and 6 movable contacts 1am-6am which can be positioned in one of 5 positions, the two sets together representing decimal digits in a bi-quinary code, the digit represented by the A contacts in the first denomination as shown in Fig. 19 being 2. Calculations are said to comprise a number of " elementary operations " each of which has two phases, a " calculating phase " and a " transfer phase." At the commencement of a calculation phase the A contacts are positioned to represent a certain number (i.e. that number set on the keyboard) some of the B contacts are closed representing another number, the closed B contacts being held in their closed position by the B polarizing winding current, and the R contacts are all open there being no R polarizing current flowing. During the calculation phase firstly the R polarizing current is applied (this does no effect the contacts of course) and secondly a current impulse is passed through some of the R control windings those windings energized depending upon which of the A and B contacts are closed. This current can pass from ge, Fig. 19, along a path determined by the A and B contacts and out at ga, in which case the R control windings energized will close R contacts representative of the sum (A + B), or the current can enter at ga and leave at ge in which case the R contacts closed represent 10 times the sum (A + B), or in place of lead ge lead ge1 can be used which results effectively in 1 being added to the B number. At the end of this current impulse the B polarizing current is cut-off and all the B contacts open. This marks the end of the calculating phase and is, except in the case of read-out operations, immediately followed by a transfer phase in which firstly the B polarizing current is applied (having no effect by itself, of course) and secondly a current impulse is passed through some of the B control windings, the path taken by the current being determined by the closed R contacts and either commencing at fe, Fig. 20, and ending at fa, in which case the B contacts closed represent the same number as that represented by the closed R contacts or commencing at fa and ending at fe, in which case the closed B contacts represent the nines complement of the closed R contacts. At the end of this current impulse the R polarizing current is cut-off and the R contacts open. Thus after a calculating phase and a transfer phase the number in the B group is some function of the number that was there and the number in the A group. A calculating phase is said to be positive when the current enters at ge, Fig. 19, resulting in (A + B) being entered in the R group and to be negative when the current enters at ga, resulting in 10 (A + B) being entered in the R group. Similarly a transfer phase is said to be positive or negative according as to whether the current enters at fe, Fig. 20; or enters at fa, producing respectively either a direct transfer from the R group to the B group or a transfer of the nines complement of the R group to the B group. Keyboard entering mechanism and read-out mechanism. Immediately prior to keyboard entry of data, cams 81, 82, Figs. 22, 23, are rotated through 180 degrees into the position shown to cam spring pressed bars 39, 40 to the right, in which position keys T0, T1 ... T9 which are shown twice for clarity, are free to be depressed. After a number has been set on the keyboard, for example 2, cams 81, 82 are rotated back to the position shown allowing bars 39, 40 to move to the left until projections on them strike the depressed key T2, which projections are so differentially positioned that the slidable A contacts controlled by the bars are moved to a position where they represent the value of the key depressed. In order to be able to read the value registered in the R group each R relay has attached to it a lever 27, Figs. 12, 13, which is normally kept out of the path of the contat-making armature 2 by a rod 30. To read a relay the rod 30 is moved away in the direction indicated to allow the lever 27 to rock under the action of the spring 29, the final position of the lever 27 depending upon whether or not the contact 2 is closed. Immediately prior to readout two bars 84, 85 are in the position shown in Figs. 22, 23 in which position lever 27 can rock out of the plane of the paper unhampered. Rods 30 are then moved and the levers 27 on relays having closed contacts position themselves in the paths of the projections on levers 84, 85. Cams 88 and 89 are then rotated through 180 degrees in synchronism with cams 81, 82 allowing bars 84, 85 to move to the left until they strike a lever 27, the movement of the bars 84, 85 positioning a suitably scaled drum 98 to indicate the digit registered in the corresponding denomination by closed R contacts, the linkage between the bars 84, 85 and the drum 98 being by a pin and slot connection between bar 84 and a toothed sector 93 pivoted to bar 85. The pressure of the bars 84, 85 on levers 27 is such that the levers 27 cannot move. The R polarizing current can thus be cut off, in which case all R contacts open, without losing the value registered. This feature also enables numbers indicated by the drums 98 to be fed back to the R contacts by applying an extra heavy R polarizing current sufficient to attract all the armatures on the R relays and then reducing the current to the normal level, only those contacts not blocked by lever 27 will be able to close and the number registered by the R contacts will be that indicated by the drum 98. Control unit. The current impulses required for an elementary operation consisting of a calculating and a transfer phase are produced mechanically during one revolution of a commutator Ig, Fig. 27, driven by a motor Mo and follow the pattern shown in Fig. 24, where the " M " impulses are those that actually cause contacts to move, and the " P " impulses are the polarizing impulses. In successive elementary operations the directions of both the " M " and the " P " currents are reversed permitting increased speed. The type of phase performed, i.e. whether positive or negative, is determined. by two sets of switching relays SR and SB, the contacts SBRo of the relays SB controlling the calculation phase and also the relays SR whose contacts SRKo control the transfer phase and also the relays SB. The complete course of an elementary operation is then as follows: initially a BP current passes from Ig through the polarizing windings SBPo of switching relays SB and the polarizing windings BPo of the B relays. The relays SB and SR together control the type of calculation being performed by suitably diverting the " M " currents through the B and R relays in a succession of elementary operations. The calculating phase consists in applying the RP cu