EPROM MOUNTED TYPE MICROCOMPUTER

PURPOSE:To facilitate development and correction of programs by making an EPROM accessed at least twice during one cycle of operation clock of a microprocessor. CONSTITUTION:A mask ROM1 that stores a program and an RAM2 that stores data are accessed separately by a CPU3. The CPU3 has an instruction register IR, a program counter PC, an arithmetic logic unit ALU, an accumulator ACC, registers IX, DR and a controlling section 3a. Externally attached EPROM10 is accessed at least twice during one cycle of operation clock of the CPU3, and instruction codes stored in even number addresses and odd number addresses are read out. The instruction codes are latched by a latch circuit 6 and then taken in an instruction register IR in the CPU3.