Patent GB-777964-A (GB)
Title: Improvements in or relating to electronic calculating apparatus
Inventor: SCHULZE JOACHIM
IPC: G06F7/52
Filed: 1954-08-10
Abstract: 777,964. Digital electric calculating-apparatus. VEB. BUROMASCHINENWERK KARLMARX-STADT. Aug. 10, 1954, No. 23264/54. Class 106 (1). An electronic calculator for performing multiplication by repeated addition of the multiplicand comprises valve counting units for the multiplier, multiplicand and product, each unit consisting of electronic counters allotted to individual digits, and control circuiting including two identical series-connected control counters (Z8, Z9), a pulse generator (M), triggers and gates whereby the multiplier counters are selected in turn and corresponding digit displacement occurs in the product counting unit. The electric multiplying arrangement shown comprises electronic decimal counters Z0-Z2, Z25-Z28 and Z10-Z16 for storing the multiplicand, multiplier and product respectively. Multiplication is performed by repeated addition of the multiplicand under control of pulses A and B supplied alternately on separate output lines by a multivibrator M, the successive selection of the multiplier digits and denominational shift in the product counters being controlled by sequentially operated relays A-D (Fig. 3, not shown). In operation, a start switch (not shown) is closed and energizes relay A which closes contacts a 0 -a 2 , a 8 , a 9 , and further contacts (Fig. 4, not shown) which cause a pulse to be supplied from an RC circuit through a delay member VF7, e.g. a flip-flop, to set a bistable trigger circuit FFO so that it opens gate GO. A-pulses then pass to a cycle counter Z8, Z9 and the tens carry pulses from Z8, as well as passing to Z9, are applied through gate G1 and contact a 8  to Z25 which stores the units multiplier digit. Z25 is stepped on until it produces a carry output which sets trigger FF1 through contact a 9  whereby gate G2 is opened instead of G1 and the A-pulses are applied to line 10S to steps on counters ZO-Z2. The first pulse through G2 also sets trigger FF3 to open gate G3. Counters Z0-Z2 supply at differential times depending on the values of the stored multiplier digits, carry outputs which set triggers FF10-FF12 to open gates G10-G12 and allow B-pulses from G3 corresponding in number to such values to pass via contacts a 0 -a 2  to counters Z10-Z12 of the accumulating product counter unit. The next carry output from Z8 resets FF3 which then opens G4 instead of G3 so that the following B-pulse resets FF10-FF12. FF3 is again set by the next A-pulse from G2 and the multiplicand is again transferred to the product unit as described above. This process is repeated a number of times depending on the multiplier digit value, i.e. on the time when FF1 is set from Z25, until 1OX10 A-pulses have been applied to the cycle counter when the carry output from Z9 sets a trigger FF5. When this trigger is reset by the next B-pulse from G4 it supplies a resetting pulse to FFO and FF1, FFO sends a pulse via relay amplifier RV which causes relay B (not shown) to be energized and relay A de-energized. Contacts b 8 , b 9  and b 0 -b 2  are then closed and a new multiplication cycle begins in which the multiplicand is transferred to product counters Z11-Z13 a number of times determined by the tens multiplier digit in Z26. Similarly, the contacts of subsequently energized relays C and D (not shown) control multiplication respectively by the hundreds and thousands multiplier digits. Circuits such as that comprising condensers C1, C10 and resistors R1, R10 may be provided to prevent spurious operation of electronic circuits upon operation of relay contacts. The relays A-D may be replaced by a step-by-step relay.