Patent GB-595553-A (GB)
Title: Improvements in or relating to accumulating apparatus
IPC: G06F7/498
Filed: 1944-05-16
Abstract: 595,553. Electric calculating - apparatus. INTERNATIONAL BUSINESS MACHINES CORPORATION. May 16, 1944, No. 9406. Convention date. May 23. 1941. [Class 106 (i)] [Also in Group XL] A hard valve accumulator has a source of electrical impulses for successively operating the conditioned trigger units of a hard valve register, entry controlling means causing an appropriate number of impulses to be applied to advance the register which comprises trigger units interconnected in a ring, each trigger unit having two stable states and being interconnected conductively to the preceding and succeeding trigger units for the purpose, when in one state, of conditioning these trigger units for switching. Similar parts are indicated by like references throughout the circuits. Trigger circuits. The main principles on which the apparatus relies are illustrated in Figs. 1, 2, 3. A trigger circuit, Fig. 1, comprises ' tubes 68a, 69a and 68b, 69b, the anodes of which are connected in. pairs to points 66b and 66a respectively and the cathodes to a line 61 of fixed potential, the resistances 62a, b, 63a, b, 64a, b being equal in pairs. The circuit is stable with either one of tubes 68a or 68b conducting and the other at shut-off. The control grids of pentodes 69a, 69b normally have sufficient negative grid bias to keep the tubes at shut-off, but when a positive pulse arrives in resistance 72 it renders the tubes 69a, 69b momentarily conducting, shuts off the tube 68a or 68b that was previously conducting and makes the other tube conducting. If the tube 68b is conducting, so that the neon tube 78 is glowing, and the point 66b is at higher potential, the unit comprising the circuit shown is said to be on and, as explained, the receipt of positive pulses in resistance 72 alternately switches the unit on and off. The unit may be maintained on or off, respectively, by closing switch 73a or 73b. In a modified trigger circuit, Fig. 2, the control grids of pentodes 69a, 69b are connected to separate resistances 72a, 72b, pulses arriving in resistance 72a turning the unit off, in resistance 72b turning it on. Switch 73a or 73b when closed renders a pulse in one or other resistance ineffective so that the unit can be maintained on or off selectively. If this selectivity is not required, the pentodes 69a, 69b may be replaced by triodes. Electronic commutator. The principles of the electronic commutator, which is of the type described in Specification 593,577, [Group XL], are illustrated in Fig. 3. Three units S1, S2, S3 of the type shown in Fig. 2 are arranged so that with one unit, say S1, on and the others off, the screen of tube 69b (S2) is at high potential so that the application of a pulse to resistor 72b renders tube 69b (S2) conducting and therefore trips S2 to on. S2 now conditions S1 to be turned off when a restoring pulse is applied via resistor 72a to the grid of tube 69a. (S1): Since the other tubes with grids connected to the resistors 72a, 72b have their screens at low potential, they are not affected by pulses. The next pulses on resistors 72b, 72a in succession turn on S3, turn off.S2, turn on S1, and so on. The electronic commutator is used for producing sequentially timed control and entry pulses and for manifesting digits in the accumulator, as described later. Oscillator and amplifiers. The machine cycle is divided into twelve portions called index points D, 9, 8 ... 0, 11, and the frequency of the oscillator is such that there is one cycle for each index point. A multivibrator consists of a two-stage, resistance coupled amplifier comprising tubes 83a, 83b, Fig. 5a, in which the output of the second stage is fed back to the input of the first stage, to produce squaretopped waves, one tube being conducting -when the other is shut off, this situation then reversing instantaneously, the voltage drops across resistors 84a, 84b being shown in Figs. 6a, 6b. Condensers 88a, 88b convert the waves to positive and negative pulses of extremely short duration on resistors 89a, 89b, as shown in Figs. 6c, 6d, there pulses being called a-phased and 6-phased, respectively. Resistors 89a, 89b feed the grids of tubes 91b, 92b, 92a, respectively, which produce amplified a-phased pulses on resistors 72al, 72b and b-phased pulses on resistors 98b (Fig. 5a) and 99b (Fig. 5n). Production of timed pulses. A pulse-producing electronic commutator, Fig. 5a (Fig. 5g, not shown), and Fig. 5m, comprising twelve units C12, C9, C8 ... C1, C0 C11 of the type shown in Fig. 2, produces pulses having a differential timed significance within the machine cycle. Resistor 72b (Fig. 5a), as already described, produces a-phased pulses for turning on the units. Resistor 72a2 (Fig. 5b) in the manner described later, produces b-phased pulses for turning off the units. As described later, a machine operation starts with unit C12 only turned on. When switch 101 is closed, advancing and restoring pulses from resistors 72b, 72a2, arriving over lines 75, 76 continuously, control the turning on and off of successive units in the manner described with reference to Fig. 3. The units produce timed pulses within each machine cycle. Thus, under the control of point 66b in each unit, positive pulses followed 1¢ index points later by negative pulses are produced on resistors 104a-l, Fig. 5n, and under the control of point 66a in units C12, C0, C11, negative followed by positive pulses are produced on resistors 104m, n, p. As described later, the positive " 12 "pulse on resistor 104a is used for initiating or terminating single entry control and for terminating carry. The " 9 " to "1" pulses on resistor 104k terminates operation of the manually controlled part of single entry control. The " 11 " pulse on resistor 104l is used for fugitive one entry and for carry. The " ¢ after D " positive pulse on resistor 104p is used to initiate subtraction. At " 12 " and " 0," negative pulses on resistor 104m, n in conjunction with tubes 110a, 110b produce positive " 12 " and "0" pulses on resistor 113, Fig. 5n, for terminating entry control and carry. Entry control device. Each order of the accumulator comprises ten trigger units, the unit that is on representing the digit. The status of the digit units is controlled by an entry control device, turned on in additive entries at a differential time in a cycle by a digitrepresenting pulse and remaining on until time " 0," during which time advancing pulses corresponding to the digit operate the digit units of the accumulator. The entry control device Et, Fig. 5d, for the tens order comprises tubes 115b, 116b in parallel with tubes 68b, 69b, while tubes 115a, 116a are in parallel with tube 68a. The device Et is normally off; but as described later under the heading " Operation " can be conditioned for turning on by having the screen potential of tube 69b raised so that the receipt of a digit-representing pulse from the appropriate resistor 104b-j, Fig. 5n, over the appropriate contacts 117t, at a differential time in the cycle, reduces the negative grid bias of tube 69b (Et) to raise the potential of point 66b and turn the device on. This raises the screen potential of tube 119a, the control grid of which has b-phased impulses continuously impressed on it from resistor 98b (Fig. 5a), so that, through condenser 122, a-phased negative pulses are produced on resistance 123, while the accompanying positive pulses on resistance 123 are attenuated by a connection to the grid of tube 119b. The negative pulses, however, increase the negative grid bias of tube 119b and reduce the current flow so that condenser 125 charges and b-phased positive pulses appear on resistance 72b, Fig. 5d. The arrival of a '' 0 " pulses from resistance 113, Fig. 5n, each machine cycle, reduces the grid bias of tube 116a to shut off Ft, the screen potential of tube 119a falls and the pulses cease in resistances 123 and 72b. Digit manifesting units. The operation of the digit manifesting units, Figs. 5d, 5q (and Fig. 5j, not shown), of each order of the accumulator is similar to that of the circuit shown in Fig. 3. Although the entry control device is turned on exactly at an index point, there is a lag of half an index point so that the digit units are turned on by b-phased pulses. The units are turned off by a-phased pulses, At0 by pulses from resistor 72a1, Fig. 5a, over line 126 and units At1-9 by pulses from resistor 72a3, Fig. 5h, over line 128, these pulses being produced continuously as long as the machine is operating, in a manner described later, so that the control of the units is entirely dependent on the number of b-phased or advancing pulses on resistor 72b. With the accumulator zeroized in the manner described later, successive advancing and restoring pulses turn on At1, turn off At0, turn on At2, turn off At1, and so on, and a first entry is indicated by the glow tube 78 which remains alight as long as the corresponding unit remains on. In making further entries, the succeeding units are switched on in turn, the unit At9 switching on At0, and so on, the last unit remaining on corresponding to the sum of the entries. The hundreds and units orders (not shown) are similar to the tens order just described. Carry-over. Normally, the carry-determining device Rt, Fig. 5q, is off, but if the appropriate order of the accumulator passes from 9 to 0 it is turned on. When unit At9 is on, the screen potential of tube 69b (Rt) is high and if, during entry, an advancing pulse is received from line 75, the unit At0 and the carry unit Rt are turned on simultaneously. The unit Rt may be turned on at any index point and stays on until time " 12," i.e. after the carry point of the cycle. The " 12 " pulse in every cycle from resistor 104a to the grid of tube 129 (Rt) shuts off Rt if it should be on. When on, the unit Rt raises the screen potential of tube 130a, Fig. 5q, and at time "11 " when a pulse arrives from resistor 1