Browse Prior Art Database

Micro Channel Point of Sale Bit Capture with Programmable Array Logic and Latch

IP.com Disclosure Number: IPCOM000113320D
Original Publication Date: 1994-Aug-01
Included in the Prior Art Database: 2005-Mar-27
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Jones III, SW: AUTHOR [+2]

Abstract

A Programmable Array Logic (PAL) and a Latch were used to provide a reliable cost effective solution to duplicate a few bits in one or two Micro Channel* POS registers external to VLSI on an Adapter card to control card functions. It uses less hardware, handles all potential timing problems, works well with a slow (cheaper) PAL, and only adds 1 load to each Micro Channel line.

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

Micro Channel Point of Sale Bit Capture with Programmable Array Logic
and Latch

      A Programmable Array Logic (PAL) and a Latch were used to
provide a reliable cost effective solution to duplicate a few bits in
one or two Micro Channel* POS registers external to VLSI on an
Adapter card to control card functions.  It uses less hardware,
handles all potential timing problems, works well with a slow
(cheaper) PAL, and only adds 1 load to each Micro Channel line.

      The PAL decodes a POS WRITE cycle which is externally captured
in a latch, clocked by the trailing edge of -ADL.  This latch is
called the POS CYCLE latch.  There is no critical timing in this path
so a slow inexpensive PAL can be utilized.  The output of the POS
CYCLE latch is fed back to the PAL.  Within the PAL is another latch
used to store the POS data bit.  If the POS CYCLE latch is active the
trailing edge of -CMD will latch the POS data bit being written.
Again no critical timing is involved.  During non-POS cycles the POS
CYCLE latch is inactive which is used to latch the current value of
the POS LATCH thus POS data is maintained until the next 'write' POS
CYCLE is decoded.

*  Trademark of IBM Corp.