Browse Prior Art Database

Generation and Application of a Microcode Patch

IP.com Disclosure Number: IPCOM000036843D
Original Publication Date: 1989-Nov-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 3 page(s) / 141K

Publishing Venue

IBM

Related People

Schwartz, AA: AUTHOR [+2]

Abstract

A method is disclosed for automatically generating a 'patch' from slightly differing object code modules and then applying it to one of them to convert it to the other. This permits maintaining the source and object code of both versions separately, yet the load data set need contain only one module and the small patch instead of two full modules. (Image Omitted)

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Generation and Application of a Microcode Patch

A method is disclosed for automatically generating a 'patch' from slightly differing object code modules and then applying it to one of them to convert it to the other. This permits maintaining the source and object code of both versions separately, yet the load data set need contain only one module and the small patch instead of two full modules.

(Image Omitted)

The example described here is a floating point accelerator (FPA) which employs a microcoded control sequencer driven by a RAM control store which is loaded by the Loadable Power-On Self-Test (LPOST). The FPA exists in two versions, C and D. They are both microcoded, but they require slightly different microcode.

In order to facilitate maintenance and minimize the risk of error, it was decided to maintain both versions of the microcode as complete source and object code modules and to include the C version microcode and a patch in the LPOST. The C version microcode is loaded and the patch applied to change it to the D level. This invention consists of this concept, the format of the patch, the means of generating it, and the means of applying it.

Fig. 1 shows the patch format. It consists of a word (eight bytes) giving the starting location of each segment to be overlayed and the number of words in the segment. It is followed by the patch data for the segment. This may be repeated as often as required. A zero length patch indicates the end. An arbitrary limi...