JPS5578359A - Check system of microprogram - Google Patents

Abstract

PURPOSE: To obtain a precision equivalent to that of the sum check system by a method easy to execute, by executing an operation processing for every one micro instruction word read and performing parity check for this read instruction code.

CONSTITUTION: Microprogram storage unit 2 which stores a microprogram, decoder circuit 4 which reads micro instruction words from unit 2 and executes them, and logical operation circuit 5 are provided, and further, parity check circuit 3 which performs parity check of instruction words read from unit 2 is provided. Check control circuit 7 is provided between address register 1 and decoder circuit 4, and a specific area of unit 2 is read in order of instructions under the control of circuit 7, and a specific logical operation between an instruction word and contents of a specific register of registers of circuit 5 is executed for every instruction read, and the result is loaded into register 1, and validity of the program is decided on a basis of the operation result for the instruction word, which is read last from the specific area, and the result of parity check.

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