JPS5668878A - Data processor - Google Patents

Abstract

PURPOSE: To store micro instruction and another micro instructions different in level from said micro instructions in the same memory, by deciding whether the read instruction is a lower instruction or a higher instruction and by executing the lower instruction in case of a higher instruction and by executing the instruction directly in acse of a lower instruction, in respect to the use of them.

CONSTITUTION: Micro instructions and micro instructions A different in level from said micro instructions are stored in main memory 1 and are read by program counter 2 and are loaded into instruction register 6. It is decided by mapping PROM 9 whether the instruction on this register 6 is a micro instruction of micro instruction A, and decision signal 24 is output. In case of a micro instruction, the instruction code is converted to the execution start address of micro instruction B by PROM9 and is given to sequnce contrller 10, and micro instruction B is executed by registers, ALU15, and so on. If the instruction on register 6 is micro instruction A, the instruction is developed to the same format as micro instruction B by code convert part 8 and is executed as it is.

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