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Address Key Register Table to Allow Multiple 16-Bit Computer Data And/Or Instruction Address Spaces for Each Level Status Block

IP.com Disclosure Number: IPCOM000040668D
Original Publication Date: 1987-Dec-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Bourke, DG: AUTHOR [+4]

Abstract

A technique is described whereby a computer processor, which uses a set of segment register banks to describe the address spaces of the programs being executed, may be extended to allow multiple data and/or instruction address spaces for each single program that is executed. The concept allows programs in either privileged or non-privileged states to use one or more instruction address spaces and one or more data address spaces available for their execution, while maintaining system integrety. Each program execution is represented by a level status block (LSB) and is able to execute with an address key register (AKR) table instead of a single AKR.

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Address Key Register Table to Allow Multiple 16-Bit Computer Data And/Or Instruction Address Spaces for Each Level Status Block

A technique is described whereby a computer processor, which uses a set of segment register banks to describe the address spaces of the programs being executed, may be extended to allow multiple data and/or instruction address spaces for each single program that is executed. The concept allows programs in either privileged or non-privileged states to use one or more instruction address spaces and one or more data address spaces available for their execution, while maintaining system integrety. Each program execution is represented by a level status block (LSB) and is able to execute with an address key register (AKR) table instead of a single AKR. The table provides up to thirty-two AKR entries where each entry consists of an instruction space key (ISK) which selects the instruction address space (IAS) from which instructions are fetched. Two operand keys select the data address space (DAS) from which data is fetched and stored. The program selects the current active AKR from the AKR table during its execution, using a non-privileged Set AKR From Address Key Table (SFAKT) instruction. This instruction allows the program to change the active AKR permanently until another permanent change is specified, or temporarily for the next sequential instruction only. The concept is significant in that it allows a non-privileged program to change AK...