Browse Prior Art Database

Multiple Adapter Command Response

IP.com Disclosure Number: IPCOM000048836D
Original Publication Date: 1982-Mar-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 3 page(s) / 69K

Publishing Venue

IBM

Related People

Laakso, MT: AUTHOR [+2]

Abstract

Many data processing products utilize miniprocessors to control a wide variety of devices. The devices are interfaced to the miniprocessor by adapters which are directly connected to the miniprocessor by an asynchronous multiwire interface.

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 3

Multiple Adapter Command Response

Many data processing products utilize miniprocessors to control a wide variety of devices. The devices are interfaced to the miniprocessor by adapters which are directly connected to the miniprocessor by an asynchronous multiwire interface.

In an asynchronous environment as described above, a "common" or "broadcast" command to a group of adapters (e.g., to gather sublevel interrupt requests) would generally require a fixed time to insure that all adapters have had time to recognize the command and place the requested data on the interface bus. This fixed time would have to be at least as long as the time required for the slowest adapter to respond. Since many products utilizing this type of interface are varied in numbers and types of adapters, cable lengths, redrive provisions, etc., this fixed time would not be optimum in almost all, if not all, cases and therefore will almost always degrade system performance.

The technique described herein eliminates the need for a predetermined fixed timeout and allows each configuration of adapters and micro-processors to automatically optimize the response to "common" or "broadcast" type commands.

Also. if many adapters share the same address on the asynchronous interface but are selected by the TD (data) portion of certain common commands, this technique insures that all adapters may respond to the TA (Address) portion of the command and the proper adapter will be selected and respond to the TD (data) portion of the command.

Figs. 1 and 2 show an implementation of the technique in a typical channel adapter.

Once an adapter attached to the interface decodes its address and a command (which activates the adapter command cycle signal), the adapter hardware controls the remainder of the sequence on the asynchronous interface. The decode circuitry for each...