Apparatus for processing data transfer requests in a data processing system

US3993981A · kind A · utility

Assignee

• Honeywell Information Systems Inc. · US

Inventors

• Frank V. Cassarino, Jr. · Weston, US
• George J. Barlow · Tewksbury, US
• George J. Bekampis · Sudbury, US
• John Conway · Miami, US
• Richard A. Lemay · Carlisle, US
• David B. O'Keefe · Westford, US
• Douglas L. Riikonen · Westford, US
• William E. Woods · Natick, US

Key dates

• Filing date: Jun 30, 1975
• Grant date: Nov 23, 1976
• Expiry date: Jun 30, 1995

Classification

• Technology area (CPC G): Physics
• CPC primary: G06F13/4213
• WIPO field: Computer technology
• WIPO sector: Electrical engineering

Abstract

In a data processing system having a plurality of units coupled for the transfer of information therebetween over a common electrical bus during asynchronously generated information bus transfer cycles, the units are coupled in a priority network and depending upon their respective priority may gain access to the bus before a lower priority unit is so enabled. Each one of the units includes apparatus for responding to a request for the transfer of information from another unit by providing any one of up to three signal responses including a positive acknowledge signal indicating an immediate response, a negative acknowledge signal indicating that the unit will most likely be busy for a relatively extended period of time and a quasi-negative response indicating that the unit will probably be ready during the next asynchronously generated bus transfer cycle.