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Bus Arbitration Selection Mechanism

IP.com Disclosure Number: IPCOM000045575D
Original Publication Date: 1983-Apr-01
Included in the Prior Art Database: 2005-Feb-07
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Hill, JA: AUTHOR [+2]

Abstract

A selection mechanism is described for enabling a data processor to be operated in either an internal or an external bus arbitration mode, with a minimum number of processor module I/O pins being required for this purpose.

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This is the abbreviated version, containing approximately 68% of the total text.

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Bus Arbitration Selection Mechanism

A selection mechanism is described for enabling a data processor to be operated in either an internal or an external bus arbitration mode, with a minimum number of processor module I/O pins being required for this purpose.

The processor module is coupled to an external bus to which is also coupled one or more storage modules. The storage modules can be accessed by the processor module and by various I/O attachments which are also coupled to the external bus. Thus, arbitration of the storage access requests is required.

The processor module is provided with a "mode select" I/O pin which is either tied up to a supply voltage line or tied down to circuit ground to determine whether the storage access bus arbitration is to be performed internally or externally of the processor module. In the internal arbitration mode, all arbitration is performed internally within the processor. This includes both internal and external storage access requests. Additional I/O pins are required for getting the external requests into the processor and for sending the request acknowledgement signals back to the sources of the requests.

In an external arbitration mode, all storage access requests go directly to an external bus control unit coupled to the external bus.

This includes the storage access requests generated internally within the processor. Thus, it would appear that additional I/O pins are required for sending these internal processor reques...