MICROPROGRAM CONTROL SYSTEM

• Main Authors: NAKAI KOICHI, YU KEIICHI
• Format: Patent
• Language: English
• Published: 23.04.1988
• Subjects: CALCULATING; COMPUTING; COUNTING; ELECTRIC DIGITAL DATA PROCESSING; PHYSICS

PURPOSE:To improve the availability of a microprogram control system by putting a switch instruction between a ROM and a RAM into a microinstruction and performing switch between the RAM and the ROM reading out the microinstruction to ensure free switching between the ROM and the RAM. CONSTITUTION:An address signals received from a microaddress register 1 are supplied to a ROM 4 and a RAM 5 and a microinstruction stored in an address is read out of the ROM 4 or the RAM 5 that is set under active state by the output of a chip selecting part 3. Then the read microinstruction is stored in a microinstruction register 6. The microinstruction includes a ROM/ RAM switching bit 7 to show whether the ROM 4 or the RAM 5 should be chip-enabled previously in the next address cycle. When the contents of the bit 7 are supplied to the part 3, either the ROM 4 or the RAM 5 to be chip- enabled is decided in the next address cycle.