Browse Prior Art Database

Checking the Loading of a Microprocessor Memory

IP.com Disclosure Number: IPCOM000087683D
Original Publication Date: 1977-Mar-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Correy, RM: AUTHOR [+2]

Abstract

Upon initial microprogram load (IMPL), executable microcode is transferred from a permanent storage device to the volatile writeable control store (WCS) area of a microprocessor memory. To ensure that the transferred data has not been altered while in permanent storage and has been installed correctly (that is in sequential order) during maintenance operations, a special code is imbedded in the microcode and is executed immediately following an IMPL.

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Checking the Loading of a Microprocessor Memory

Upon initial microprogram load (IMPL), executable microcode is transferred from a permanent storage device to the volatile writeable control store (WCS) area of a microprocessor memory. To ensure that the transferred data has not been altered while in permanent storage and has been installed correctly (that is in sequential order) during maintenance operations, a special code is imbedded in the microcode and is executed immediately following an IMPL.

At periodic intervals in the microcode, the object code is set to be equal to the memory address at which it should reside following IMPL. The microprogram verifies each of these locations, and then, if desired, makes use of a table, also imbedded in the microcode, to replace the contents of the check locations with executable microcode.

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