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Program to Count Microcode Instructions

IP.com Disclosure Number: IPCOM000079381D
Original Publication Date: 1973-Jun-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Hedeman, WR: AUTHOR

Abstract

The drawing shows a program to test the machine instructions of a computer, to find out how many microcode instructions a machine instruction takes. The program uses the feature of the Diagnose instruction that it can produce a machine check (a hardware failure signal), after a selected number of microcode instructions have been executed. This number is incremented and the operation is repeated, until no machine check occurs in the test instruction and the program advances normally to its next machine instruction. This next instruction is an invalid instruction that produces a program check, and thereby signifies the end of the operation of counting the microcode instruction.

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Program to Count Microcode Instructions

The drawing shows a program to test the machine instructions of a computer, to find out how many microcode instructions a machine instruction takes. The program uses the feature of the Diagnose instruction that it can produce a machine check (a hardware failure signal), after a selected number of microcode instructions have been executed. This number is incremented and the operation is repeated, until no machine check occurs in the test instruction and the program advances normally to its next machine instruction. This next instruction is an invalid instruction that produces a program check, and thereby signifies the end of the operation of counting the microcode instruction.

The instructions to be tested and associated data are located in a table, and at the start of the program the test instruction is moved to a test area in main storage. The 8-bit cycle counter for the Diagnose instruction is set to an initial value, and the Diagnose instruction then operates to increment the counter for each microcode instruction of the test instruction. On overflow of this counter, a machine check is produced. In response to a machine check, the operation branches to A in the drawing.

The first decision block tests the old program status word, to distinguish between machine checks that occur during execution of the Diagnose instruction and machine checks that occur during the operation of the test instruction. The second decision block...