Self-sequencing memory

Abstract

A self-sequenced read only memory is shown wherein each word line contains dynamic logic circuits for energizing a next word line after the fixed time delay provided by the dynamic logic circuits. Self-sequencing inverters are physically placed within the array area thereby increasing reliability and reducing circuit wiring. When used as a microprogram control storage, the memory is divided into a plurality of self-sequenced control routines. When a certain function is to be performed, the first word line of the control routine for performing the selected function is energized. Since each word line includes a one cycle delay and is wired to the next sequential word line, no separate timing or address control is required to address word lines within a selected control routine. Once a control routine is energized, sequential microinstructions will be automatically fetched including branch and branch-on condition instructions. Branch operations can be implemented by connecting one of the outputs of the array to the branched-to word line. Branch-on condition can be implemented by gating the inverter in the branched-to instruction with an AND circuit. By virtue of the self-sequencing of the memory, branched-to word lines can be sequentially accessing memory words simultaneously with sequential memory word fetch operations within the branched from control routine. The branched-to control routine thereby acts as a modifier routine to modify the bit patterns of the memory words which continue to be fetched by the branched-from control routine.