Patent GB-878697-A (GB)
Title: Fluid-pressure digital computer
IPC: F15C3/00
Filed: 1958-02-19
Abstract: 878,697. Calculating-apparatus. GOLDMUNTZ, L. A., HELD, K., KAY, A. F., ARONSON, R., and KOTIK, J. Feb. 19, 1958 [Feb. 19, 1957], No. 5423/58. Class 106 (1). [Also in Group XXIX] Digital computing apparatus comprises fluidpressure valves adapted to perform basic logical operations and interconnected by fluid pressure conducting means. Fluid-pressure relays.-A flat piston 21, Fig. 2, is arranged in a chamber 19 cut in a sheet metal plate 12a so as to slide between two end positions under the control of pressures applied to control ports 17a, 17b. By using a return spring, the piston may be controlled by a single pressure applied to one port. The piston 21 has a cut-away portion 22 which serves to connect an output port 17d with one or the other of two input ports 17c and 17e according to the position assumed by the piston 21. The ports are formed by slots cut in the plate 12a and the latter is sandwiched between other plates which enclose the chamber 19 and the ports. To reduce the frictional load on the piston 21, a balanced arrangement of ports may be employed. Thus, e.g., in the arrangement shown in Fig. 4, two connected output ports 46a in the adjacent plates lead from the centre of the chamber around a narrow portion of the piston 38 which opens either one pair of input ports 44a, 44b, as shown, or another pair of input ports 45a, 45b. Another arrangement, Fig. 3, employs a rocking piston 28 controlling perpendicularly arranged ports. A double relay, Fig. 9a, connects output ports x, y either to input ports a, b respectively, or to input ports b, c respectively. Many relays may be formed in each plate and many plates superposed as shown in Fig. 1, thinner plates not formed with relay chambers being interposed. The ports leading to the relay chambers terminate in bores 18 aligned with suitable passages in the interposed plates. To facilitate manufacture, such assemblies may comprise plates of certain standard forms, e.g. 54, 63, Figs. 7 and 8, which may be superposed to form desired through passages, selected holes in the plates 63 being plugged. Logical devices.-The apparatus makes use of high, intermediate and lwo pressures (pressure differences of 10 lb. per square inch being adequate). An "or" gate may be formed by applying the intermediate pressure to one of the input ports. Then, if the high pressure is applied also either to the other input port or to the other control port, the high pressure will be applied to the output port. This is represented by Fig. 10b in which the application of the intermediate pressure to the one control port is not shown, E is the other control port, G the output port, + represents the high pressure applied to one input port, and F the other input port. "And," "invert," " inhibit" and multiple "or" and "and" devices are also described, together with bi-stable devices, Figs. 10j and 10k (not shown) and a frequency halver device, Fig. 10l (not shown). Binary shift register with key input.-Each order comprises an input relay, e.g. 118, Fig. 11, a double relay 119, a transfer input relay 121 and a transfer output relay 122. A double relay, Fig. 9a, is represented as shown in Fig. 10m. In addition, the input keys 112 (1) and 114 (0) directly control the pistons of relays 111, 113 and are associated with a keyboard actuation relay 116 and a keyboard output relay 115. The keyboard actuation relay 116 and all of the input relays 118 and of the transfer input relays 121 are connected for common actuation. The pressures indicated (+ or -) correspond to the depression of the key 112 after the register has been reset by depression of a key 109 which operates a relay 108. Normally, the latter applies high pressure to the ports marked R. When the key 112 is depressed, the output from the keyboard output relay is high and the connected actuation and input relays are actuated. Thus, the input relay 118 applies high pressure to the double relay 119 and that relay also is actuated and applies high and low pressures respectively to the output lines 1A, 1B to registera "1" for that order. When the key 112 is released, the connected relays 116, 118, 121 restore but the first order relay 119 remains actuated due to the connection of its output 1A to the upper inlet of the relay 118. Moreover, the transfer input relay 121 now applies high pressure from the output 1A to the transfer output relay 122 which is thus actuated to apply high pressure to the lower inlet of the input relay 123 of the next order. Thus, on depression of another key, when the connected relays 116, 118, 121 are again actuated, the relay 123 will apply high pressure to the double relay 124 to register "1" in the second order. If the "0" key 114 is depressed, the connected relays 116, 118, 121 are again actuated, but as the output of the relay 111 is low, the input to the lower inlet of the relay 118 is also low and the relay 119 restores and applies low and high pressures respectively to the outputs 1A, 1B to register "0." On release of the key 114 and depression of a further key, the registration of " 0 " is progressed along the register in a similar manner to a registration of "1." A simplified shift register, Fig. 14 (not shown), has, for each order, only a single output which is at high or low pressure depending on whether "1" or "0" is registered. Adder.-A binary adder, Fig. 15, receives signals corresponding to one multi-digit number from the outputs 1A, 1B; 2A, 2B; ... of a shift register as shown in Fig. 11 and further signals corresponding to a second multi-digit number from the outputs 1, 2 ... of a shift register of the simplified type referred to above. The sum is indicated by devices 131, 135 ... which may be similar to the relays but arranged as visible indicators. A typical order, e.g., the second, comprises a double relay 134 to which the input signals from 2A, 2B and 2 are applied as indicated and a relay 133 to the control port of which the carry signal from the next lower order is applied. The output of the latter is high if any one, or all three, of the inputs 2A, 2 and the carry input are high, otherwise it will be low. Each order also has a carry subsection comprising a double relay 136 and a relay 137 which are connected to operate with the relays 134 and 133 respectively. The output of the relay 137 (which forms the carry input of the next order) is high if any two, or all three, of the inputs are high.