Browse Prior Art Database

Method for Using a Thirty-Two Bit Slave in a Sixteen-Bit Micro Channel Architecture System

IP.com Disclosure Number: IPCOM000101140D
Original Publication Date: 1990-Jul-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

Prais, MW: AUTHOR

Abstract

This article describes a method and hardware implementation for allowing a memory slave to be used in both a 16- and 32-bit MICRO CHANNEL* architecture system.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 100% of the total text.

Method for Using a Thirty-Two Bit Slave in a Sixteen-Bit Micro Channel Architecture System

       This article describes a method and hardware
implementation for allowing a memory slave to be used in both a 16-
and 32-bit MICRO CHANNEL* architecture system.

      The method disclosed herein provides data steering for a 32-bit
memory slave so that it can run in either a 16-bit MICRO CHANNEL
architecture system or in a 32-bit MICRO CHANNEL architecture system
that does not have BYTE ENABLE signals (-BE0 to -BE3).  The L before
a signal denotes that these are the latched versions of the signals.

      Since there are no BYTE ENABLE signals in the 16-bit system,
these signals are effectively generated by the slave using -SBHE, A0
and A1 when operating in 16-bit mode.  When in a 32-bit system, the
BYTE ENABLE signals provided by the system are used for data
steering.

      The matrix of transceivers is shown in the drawing.  As can be
seen, in a 16-bit system, the Programmable Array Logic (PAL), using
address bits A0 and A1, -SBHE and the 16 BIT MODE signal, enable
transceivers 1, 2, 3 and 4, as required, while transceivers 5 and 6
are disabled.  In 32-bit mode, the PAL uses -BE0 through -BE3 to
enable transceivers 3, 4, 5 and 6, as required, while transceivers 1
and 2 are disabled (*).
*  Trademark of IBM Corp.

      Reference
(*)  IBM Personal System/2 Seminar Proceedings, Vol. 5, Number 3, May
1987.