Abstract: A circuit for generating refresh signals for a dynamic, random access memory is disclosed. The circuit comprises a timer which periodically generates refresh request signals. Each refresh request signal increments a refresh request counter. In normal system operation, after a memory access cycle, a refresh cycle is performed if there is a non-zero count in the counter. At the start of each refresh cycle, the counter is decremented and the refresh address to the memory is changed. Refreshing of the memory continues until the count is zeroed. If, for some reason, memory accesses are not performed within the memory refresh time limit, the count in the counter reaches a critical limit and a non-maskable interrupt is generated to the system processor causing it to access an interrupt vector in the memory and force refresh cycles.

Abstract: A memory circuit is provided wherein the speed of the downward transition of the memory cell is increased. A plurality of memory cells are coupled between a select line and a current drain line. A first means is coupled to the select line for providing current to the plurality of memory cells and is responsive to a select signal having first and second states. A first PNP transistor has an emitter coupled to the current drain line for drawing any charge from the plurality of memory cells when the select signal transitions downward. A second means is coupled to the base of the first PNP transistor and is responsive to the select signal for setting the current level in said first PNP transistor. A second embodiment additionally includes a second PNP transistor having an emitter coupled to the select line and a collector coupled to said second supply voltage terminal for removing charge stored on the select line.