GB1079594A - Improvements in or relating top fluid pressure operated calculating machines - Google Patents

Abstract

1,079,594. Fluid controlled calculating apparatus. NATIONAL CASH REGISTER CO. July 5, 1965 [July 22, 1964], No. 28345/65. Heading G4P. Fluid relays in a fluid-operated calculating machine comprise a stack of plates with a piston accommodated in a recess in the stack, the piston being reciprocable so that inlet ports in the plates may be brought into coincidence with outlet ports or disconnected therefrom. Addition.-Numbers entered in decimal form on the keyboard are first converted into binary coded decimal form. When, for example, the amount key 62a (Fig. 29) representing the digit "7" is depressed, relay 238 is operated to give output flow along channel 239 which results in the switching of relays 242a, 242b and 242c and hence flow along channels 234, 235, 236 but not along channel 237. These outputs are applied to a K register (Fig. 28) which comprises several stages each having four input flip-flops and four memory flip-flops. The output from the K register is used in three ways, (a) it is applied to a keyboard indicator 22, (b) it is applied to a binary conversion unit, (c) it is transferred to an adder 34a (not described) where it is added to the contents of the A register and the result stored in the A register. The rotation of the indicator segment 135 (Fig. 17) is controlled by pistons 127-130 which are operated or not according to whether or not a binary "1" or " 0 " is stored in the associated chambers 126a. The distance moved by the pistons is weighted according to their binary value. The binary conversion unit 38 (Fig. 22) comprises pistons 143 to 146 which control the positions of slides (193-196, Fig. 25, not shown) so that certain notches in the slides are in alignment to define a slot representing the decimal digit which is then printed. Multiplication.-On depression of an "enter" multiplier key the number set up on the keyboard is entered into the M register. The multiplicand is then entered into the K register. On depression of the " multiply key " the product of the K register and the M register is entered in the A register and the M register is then set equal to the A register. Error preventing.-Relays are also described (Fig. 31, not shown) in which if the fluid pressure is cut off the pistons are locked in position until the power is restored. Since the switching of one of the relays associated with the keys (62a, Fig. 29, not shown) is only possible when all the lower amount relays have not been switched, simultaneous depression of two keys 62a results in only the lower amount key being effective.