Patent GB-1406117-A (GB)
Title: Electronic memory systems
IPC: G11C11/405
Filed: 1972-11-10
Abstract: 1406117 Memory systems HONEYWELL INFORMATION SYSTEMS Inc 10 Nov 1972 [3 Jan 1972] 52118/72 Heading G4C A memory system comprising a group of storage cells and an auxiliary control cell, the contents of which are inverted during each read operation, includes circuitry for delivering a signal representing the result of an exclusive OR operation on the data read from a selected storage cell and the auxiliary storage cell. As described with respect to Figs. 3a, 3b, 3c, the memory comprises an integrated circuit array 200 consisting of four sectors 200a-200d each storing data in three transistor (MOS FETs) cells arranged as a 32 by 16 matrix, each matrix having a data sense line D/S1-4. Associated with each sector is an additional row of control cells DC0-DC15 which effectively count the number of times the column is accessed to determine whether the stored data is held in real or inverted form. Since sensed data, which is read out in inverted form does not consequently need to be re-inverted before being written back, both the access time and the energy dissipated within the memory are reduced. Row and column selection.-During a precharge interval #1, transistors 267 in each of row decoder circuits 260-0,-260-63 are rendered conductive to charge storage node 268 negatively and transistors 367 in each of column decode circuits 360-0,-360-31 are rendered conductive to charge storage node 368 and boot strap capacitances 383, 384 negatively. Consequently with X and Y address signals and their inverses applied from buffer registers 240, 340 to transistors 261, 266, 361, 366 in each of the decoder circuits all except a selected node 268 and a selected node and pair of boot strap capacitances 368; 383, 384 are discharged so that a signal is applied on one of the column leads Y 0 -Y 31  and one of the row leads X 0 -X 63 . Read out and write in for a selected cell.-Read out information stored on the parasitic capacitance C of the selected cell is effected during an interval # 2  when a signal on the selected column line # 2 -0... # 2 -15 renders conductive transistor R in each of the cells of a column so that if a "1" is stored transistors S conduct to discharge capacitors C1 of digit sense line B0-B63 (charged negatively during the interval #1) to apply a signal via a selected transistor 280-0 ... 280-63 of the selected row to one of the digit sense lines D/S. In a similar manner, capacitor C1 of control line DC is selectively charged (having also been charged during the interval #1) in accordance with the contents of the control cell DC0-DC15 of the selected column. Read out circuit 500 performs an exclusive OR operation on the data read from the control cell and the selected cell to derive a data out signal. During a subsequent interval # 3  automatic refreshing takes place, the information on the digit sense lines B0-B63 and control line DC which represents the complement of the read out data being read back into the selected cell. In a write operation, after the signal #2, node 400.4 in write circuit 400 is charged to a level dependent on the state of the line DC. Subsequently storage node 400.14 is charged selectively in accordance with an exclusive OR operation on the data to be stored fed in on the line data in and the data on line DC, the resulting output signal at terminals A, B onditioning write buffer 404 controlling the data sense lines DS so that via one of the transistors 280-0 ... 280-63 the data is written in to the selected cell in real or inverted form as required.