Patent GB-935176-A (GB)
Title: Memory updating
IPC: G06F7/38
Filed: 1961-09-29
Abstract: 935,176. Digital electric calculating-apparatus. SPERRY RAND CORPORATION. Sept. 29, 1961 [Oct. 7, 1960], No. 35181/61. Class 106 (1). A storage device comprising at least one register having a plurality of bi-stable stages storing a binary number comprises undating means which includes means to apply an updating signal to one stage, said signal switching the stage to a selected state if it is not already in that state, means to produce a switch signal if said one stage is switched, and gating means responsive to the presence and the absence of said switch signal, said gating means being inhibited if the updating has been carried out in said one stage, and said gating means being effective if updating has not been carried out in said one stage to pass an updating signal to the next higher order stage. The arrangement described is a magnetic thin film memory comprising an array of bi-stable elements. First embodiment, Fig. 1.-In this embodiment, updating signals take the form of equivalued pulses on an input line 10. The row to be updated is selected by a bias signal applied to the appropriate row line 72-80, which applies a field transverse to the horizontal easy axes of the magnetic elements, and only in the selected row are the switching pulses on the vertical lines effective. The input pulse is applied to a delay 82 and a driver 84, the driver 84 applying a signal to switch to " 1 " the element, such as 22 in the lowest order of the selected row. If this element is already in its " 1 " state, no switching takes place and the input signal is passed from delay 82 via a gate 94 to line 102 in the next higher stage. If the element 22 is in its " 0 " state, it is switched by the signal on the line 86 to produce an output on a line 88 which inhibits the gate 94, thereby preventing the input pulse from affecting higher order stages. If the element 22 was in its " 1 " state, a signal is applied over the line 102 to the element 24 and this is effective over a line 104 to set the element 22 to its " 0 " state. The higher order elements 26, 28, 30 are connected via similar gating arrangements so that the whole arrangement functions as a binary counter for the selected row. Second embodiment, Fig. 2.-In this embodiment, the updating number is applied as an addend from an addend register 170 in parallel to the selected row. Assuming a " 1 " is stored in the 2 degrees order, a signal is passed via an " or " gate 172 to a delay 178 and to a driver 180 which applies a pulse to a line 182, this pulse switching an element 150 in the biased row to " 0 " if it is not already in that state. If the element is already in the state " 0 " a gate 190 is not inhibited and passes a signal delayed at 178 via a driver 192 which switches the element 150 to " 1." If the element 150 is switched to " 0," an output on a line 184 inhibits the gate 190 and enables a gate 194 to pass the signal delayed at 178 to the next higher order via an " or " gate 174, as a " carry " to the next order. The other elements 152, 154 are connected to gating arrangements similar to those of the element 150, so that the whole arrangement functions as an accumulator for the selected row. Specification 845,604 and U.S.A. Specification 2,900,282 are referred to.