MICROPROGRAM CONTROL SYSTEM

摘要

PURPOSE:To make the concurrence circuit of the overflow signal of a refresh counter and a read/write memory access request signal needless by defining the overflow signal above as an interrupt condition of a microprogram. CONSTITUTION:The overflow signal of refresh counter 7 which is overflowed at the time of a refresh cycle is transmitted to interrupt control circuit 8. Circuit 8 regards this signal as one interrupt signal and controls selection between this signal and other interrupt signals. Then, a fixed address is determined on a basis of one interrupt signal by the control memory address selection circuit and is set to control memory address register 10 to read out control memory 11. A micro instruction set in control memory instruction register 12 is decoded by decoder 13 to generate an independent refresh in dication signal, thereby executing the refresh operation through memory control circuit 14 by memory unit 15.