Browse Prior Art Database

Diagnostic Controls System

IP.com Disclosure Number: IPCOM000075518D
Original Publication Date: 1971-Oct-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 3 page(s) / 51K

Publishing Venue

IBM

Related People

Johnson, AM: AUTHOR [+2]

Abstract

Special diagnostic functions have been provided on recent generations of computers to help make the systems more diagnosable. Since the importance of making computers self-diagnosable has grown continuously, there is a critical need for efficient diagnostic systems to keep the cost down but yet provide the maximum in diagnostic functions. The improved controls illustrated in the-sketch:. 1) provide a system through which unique diagnostic functions can be implemented efficiently; 2) provide for adding diagnostic functions without requiring additional hardware; 3) provide a means of protecting normal CPU operations from failures in the diagnostic controls.

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Diagnostic Controls System

Special diagnostic functions have been provided on recent generations of computers to help make the systems more diagnosable. Since the importance of making computers self-diagnosable has grown continuously, there is a critical need for efficient diagnostic systems to keep the cost down but yet provide the maximum in diagnostic functions.

The improved controls illustrated in the-sketch:.
1) provide a system through which unique diagnostic

functions can be implemented efficiently;
2) provide for adding diagnostic functions without

requiring additional hardware;
3) provide a means of protecting normal CPU operations

from failures in the diagnostic controls.

The Diagnostic Control System consists of a diagnostic key latch 1, a diagnostic register DIAG and the use of nondiagnostic hardware to provide special diagnostic functions. The diagnostic key is used to protect the nondiagnostic operation of the processor from being disturbed by failures in the diagnostic hardware. This means that the addition of diagnostic hardware does not reduce the availability of the system to the customer. DIAG provides:
1) the diagnostic functions needed for diagnosing the basic

data flow
2) the controls for gating the many special diagnostic functions.

Without the second capability, it would be impossible to generate the many machine checks or force the numerous traps. The register ABRTY is the nondiagnostic hardware used on this system to provide diagnostic functions. The content of the ABRTY can be set and "frozen" by a special diagnostic decode. Thus, a register that is normally changing every cycle becomes frozen to one value. Now, the appropriate Diagnostic Group Gate can be activated to enable the desired diagnostic functions.

Latch 1 is independent of all other diagnostic hardware. It has its own unique set and reset. It allows other diagnostic facilities to be set and reset but prevents the outputs of these diagnostic facilities from exerting any influence over the processor when the key is inactive.

The diagnostic register acts as...