Patent GB-595554-A (GB)
Title: Improvements in or relating to accumulating apparatus
IPC: G06F7/498
Filed: 1944-05-16
Abstract: 595,554. Electrical calculating- apparatus. INTERNATIONAL BUSINESS MACHINES CORPORATION. May 16, 1944, No. 9407. Convention date, May 23, 1941. [Class 106 (i)] A hard valve accumulator has a source of electrical impulses and means to apply a number of these impulses, corresponding to the digit to be additively entered, to a hard valve register, each register having a number of trigger units, fewer than the radix of the notation in use interconnected in a ring, with an additional trigger unit external to the ring, each trigger unit having two stable states and the trigger units in the ring being interconnected conductively so that the status of one trigger unit conditions the next for switching at a subsequent impulse, any digit being represented by a combination in one or other of their two stable states of one of the trigger units in the ring and the extra trigger unit. Similar parts are indicated by like references throughout the circuits. Trigger circuits. The main circuit is built up of a number of trigger circuit units operating in the manner described in Specification 595,553 (Figs. 1 and 2, not shown), a trigger unit being said to be on when the point 66b is at a higher potential, and said to be off when the point 66a is at the higher potential. Electronic commutator. As described in Specification 593,577, [Group XL], a multivibrator supplies pulses to an electronic commutator (Figs. 5a, 5g, 5m, not shown) to produce pulses of extremely short duration at differential times within the machine cycle on resistors 104a-p (Fig. 5n, not shown), the pulses being used for entry and control purposes. Accumulator. The tens order of the accumulator is shown in Figs. 5d, 5j, 5q. The entry control device and the manner of its control in making additive and subtractive entries is as described in Specification 595,553, but the digit manifesting means differ. Instead of having a unit At0 to At9 for each digit of the order, there are five units At0-5, At1-6, At4-9 and an extra unit Xt which is off if the digit is below 5 and on if above 5. In the manner described in the aforementioned Specification, an entry produces the appropriate number of b-phased advancing pulses on resistance 72b, Fig. 5d, while a-phased restoring pulses arrive over lines 126, 128 as long as the apparatus is working, so that commencing with the unit At0-5 on, unit At1-6 is turned on, At0-5 is turned off, unit At2-7 on, unit At1-6 off and so on, and an entry or the result of a calculation is indicated by the glow tube 78 which remains alight as long as the corresponding unit remains on. When on, unit At4-9 raises the screen potentials of tubes 69a, 69b of the unit Xt, the control grids of which are connected to line 75 to which the advancing pulses are applied, so that the next pulse, besides turning on At0-5, also reverses the state of unit Xt. A restoring pulse turns off At4-9 and the screen potentials of tubes 69a, 69b (Xt) fall so that further advancing pulses do not affect the unit Xt until unit At4-9 is again turned on. Carry-over. Carry-over is controlled by a carry-determining element Rt, Fig. 5q, which is turned on when the order of the accumulator passes from 9 to 0, i.e. when the unit Xt is turned off, when point 66a (Xt) rises in potential and produces a positive pulse on resistance 290 to reduce the negative grid bias of tube 69b (Rt) to turn the unit Rt on. As in Specification 595,553, Rt remains on till after carry-over takes 'place at time " 11 " and is switched off at time " 12." Operation. The key - setting and entry, additive or subtractive is as described in the aforementioned Specification. Indicating. The numbers in the accumulator are displayed on cathode-ray tubes in the manner described in Specification 595,553, except that the pentodes 237 in that Specification are replaced by pentagrids, Fig. 5f, the No. 1 grids of which are connected to the point 66b of the appropriate units At0-5, At1-6, &c., and the No. 3 grids of pentagrids 237(0) to 237(4) are connected to point 66a of unit Xt and those of pentagrids 237(5) to 237(9) to point 66b of unit Xt. The bias on either No. 1 or No. 3 grid of any one tube 237 is sufficient to prevent current flow therethrough unless both the point 66b in unit At0-5, At1-6, &c. and the point 66a or 66b in unit Xt to which the tube is connected are at high potential. In this case, the tube 237 corresponding to the digit represented by the accumulator units becomes conducting when the Nos. 2 and 4 grids have their potentials raised by a selector 206. The selectors and their operation are as described in the afore-mentioned Specification. Zeroizing accumulator. The accumulator is zeroized in three steps, (1) by turning off all the units Xu, Xt, Xh which are on ; (2) by turning off all the digit manifesting units Au1-6, Au2-7, &c. which are on; (3) by turning on all the units Au0-5, At0-5, &c. which are off. (1) When switch 261, Fig. 5h, is opened, the screen potential of tube 258 is raised so that a-phased pulses applied continuously to the grid cause increased current flow and b-phased positive pulses appear on resistor 263 to reduce the grid bias of all tubes 292, Fig. 5q, and increased anode current to each tube flows through resistance 62b to turn off any units Xu, Xt, &c. which may be on. (2) The units Au1-6 &c. are turned off in the manner described in -Specification 595,553. (3) A second manipulation of switch 261 reduces the grid bias of tubes 266, Fig. 5d, in the manner described in the afore-mentioned Specification and the units Au0-5, At0-5, &c. are turned on Specification 542,927 also is referred to.