APPARATUS FOR EXPANDING DATA MEMORY

摘要

The circuit for extending the data memory area restricted by address signal from a CPU to transmit or receive data to or from a main memory, comprises AND gates (G1,G2) for combining a writing signal (SA) and a reading signal (SB) from the CPU with an address signal fromthe CPU and an extension address generating unit (30) for outputting a predetermined address signal by data signal and address signal from the CPU. An extension memory (20) designates a memory allocati area by the address signal fromthe extension address generating unit (30), and writes and reads data by the signals (SA)(SB) from the gates (G1,G2) to transmit or receive the data to or from the main memory (10) through a data bus (DB).