MEMORY AREA SWITCHING CIRCUIT

PURPOSE:To ensure the effective use of a memory area by providing an address switching circuit, data switching circuit and a word/byte changeover external switch, and converting the memory area into the one exclusive for byte access. CONSTITUTION:A selection conversion circuit 10 switches addresses and selection signals of high-order/low-order bytes. A data switching circuit 12 performs the changeover between high-order and low-order 8 bits. A word/byte changeover external switch 13 is operated to give commands to both circuits 10 and 12. Then a memory 9 for high-order 8-bit data is converted into a memory for low- order 8-bit data. In other words, a memory area exclusive for access (16 bits) is converted into a memory area exclusive for byte access (8 bits).