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Browse Prior Art Database

Trace

IP.com Disclosure Number: IPCOM000089656D
Original Publication Date: 1977-Dec-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Boca Raton: AUTHOR

Abstract

The trace facility is designed as a debug or system measurement tool for use by computer programmers who are thereby able to map the execution of a computer program. It is especially useful in a system such as the IBM Series/1. This facility can be enabled by the interrupt level, and will trace instructions executed only on the selected levels. The trace facility is designed so that the trace for a particular routine appears as if that was the only level or routine in execution on the system. For example, priority interrupts, supervisor calls, class interrupts, and rate control (instruction step, stop on address) are transparent to the traced routine.

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Trace

The trace facility is designed as a debug or system measurement tool for use by computer programmers who are thereby able to map the execution of a computer program. It is especially useful in a system such as the IBM Series/1. This facility can be enabled by the interrupt level, and will trace instructions executed only on the selected levels. The trace facility is designed so that the trace for a particular routine appears as if that was the only level or routine in execution on the system. For example, priority interrupts, supervisor calls, class interrupts, and rate control (instruction step, stop on address) are transparent to the traced routine.

In general, if trace is enabled on a particular level, a trace interrupt will occur preceding each instruction to be executed. The trace interrupt automatically copies into a specified main storage location. the general purpose registers, the level status register, the address key register, and the instruction address register of the selected level. Also, the supervisor state is entered, all priority interrupts are masked, and the machine begins executing a software trace routine located at a specified storage location. The software routine may choose to print the information gathered, collect more information, or perform some other function it deems useful. Upon completion of the trace, routine control is restored to the main instruction stream until the next instruction to be traced is executed.

To implement the above within the Series/1 architecture, certain instructions are defined to deviate fr...