Dismiss
InnovationQ will be updated on Sunday, Oct. 22, from 10am ET - noon. You may experience brief service interruptions during that time.
Browse Prior Art Database

Self Adjusting Priority Resolver

IP.com Disclosure Number: IPCOM000082504D
Original Publication Date: 1974-Dec-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Christensen, NT: AUTHOR

Abstract

In a two-processor system, the described mechanism maintains different priority levels between the processors, even though they are physically identical.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 53% of the total text.

Page 1 of 2

Self Adjusting Priority Resolver

In a two-processor system, the described mechanism maintains different priority levels between the processors, even though they are physically identical.

Consider two processors in a single system which are physically identical. In general, each processor operates independently and asynchronously, but there are times when the processors must communicate with each other. Whenever it happens that the processors want to communicate simultaneously (i.e., both processors raise 'request' signals on the same cycle) priority must be resolved between them. Since the processors are identical, there is no priority between them. The resolution of priority should be such that: 1) Only one processor will get priority (win). 2) The processor which loses is assured of winning the next time a conflict occurs.

The mechanism which accomplishes this consists of two priority latches, one in each processor, and a line from each priority latch to the other processor. It is assumed that there already exists a pair of `request' lines between processors, and that the priority latches are in opposite states. The mechanism being described assures that if the priority latches are not in different states (since the processors are identical, this will always be the case before the first request is raised) it will adjust itself such that they are.

The mechanism operates as follows. When only one request is active between processors, there is no conflict and the priority latches, if they are different, are not affected. When two requests occur simultaneously, the processor...