Patent GB-791834-A (GB)
Title: An electronic calculator program device
IPC: G06F9/32
Filed: 1955-01-13
Abstract: 791,834. Digital electric calculating-apparatus. INTERNATIONAL BUSINESS MACHINES CORPORATION. Jan. 13, 1955 [Jan. 15, 1954], No. 1067/55. Class 106 (1). An electronic programme device comprises a chain of trigger elements constituted by a home position trigger, a series of intermediate triggers and a last trigger, each operable to an on or off condition, only one of said triggers being in an on condition at any one time, and means for normally stepping the on condition through all of said intermediate triggers from the home position trigger to the last trigger in a predetermined sequence, in which each of a plurality of said intermediate triggers is connected to gating means operably to provide a connection for stepping the on condition to the next trigger in the sequence and to another gating means operably to provide a connection to another intermediate trigger in the sequence subsequent to said next trigger, whereby the on condition may be transferred to said other intermediate trigger to skip certain triggers in said sequence. The invention is described as a modification of the calculator of Specification 673,759, in which calculations are performed as a pre-assigned (by plugging) sequence of arithmetic operations (e.g. " add," " multiply," &c.), each type of arithmetic operation being under the control of an associated programme function means which operates by conditioning a selected number of sub-programme means (e.g. " readin," " reset," &c.), those selected for conditioning depending upon the particular type of arithmetic operation being controlled and being actuated at fixed times within a primary timing cycle of the machine, the modification being that if certain of the sub-programme means (for example " reset ") which have their own period in each primary cycle are not conditioned then the primary cycle is shortened by omitting that portion corresponding to the unconditioned subprogramme means. The programme function means necessary for a particular calculation are plugged in the desired sequence to 20 sets of programme hubs 1, 2-20, Figs. 1A-1C (only hubs 1, 10, 14 and 20 being shown), which are sequentially placed under voltage by a programme ring consisting of 20 cascadeconnected Eccles-Jordan triggers 12-31, only one being " on " at any one time, which is normally stepped on one stage for each cycle of a Primary Timer consisting of 23 ring-connected triggers " step 1," " step 2," ... step 23," which is stepped by clock pulses applied to the left-hand grids of each trigger from an " and " gate 235, there being a connection from " step 2 " of the Primary Timer via a normally open " and " gate 259 and a cathode follower 262 to a programme advance lead 65 which supplies the stepping pulses to the Program Ring. The stages " step 2 " (terminal 8) and " step 3 " (terminal 3) of the Primary Timer are connected via an " and " gate 172, of the type described in Specification 741,595 (which is referred to), and stages " step 2 " and " step 9 " are linked by an " and gate 174, thus by closing gate 172 between " step 2 " and " step 3 " and opening gate 174 between " step 2 and " step 9," which is done by energizing a " skip reset " load 331, the Primary Timer advances direct from " step 2 " to " step 9 " omitting " steps 3-8 " during which time the only sub-programme means that can operate is the resetting means. Hence if the " skip reset " lead is energized the Primary Timer omits the portion devoted solely to resetting. In a similar way by energizing a lead " skip carry " the portion devoted to carry operation (" step 20 "-" step 23 ") is omitted and by energizing a " no skip " lead no portion is omitted. Specification 750,259 also is referred to.