Browse Prior Art Database

Loadable Programmable Logic Array

IP.com Disclosure Number: IPCOM000101830D
Original Publication Date: 1990-Sep-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 3 page(s) / 99K

Publishing Venue

IBM

Related People

Akrout, C: AUTHOR [+4]

Abstract

Electronically controlled replacement of faulty AND/OR terms of a classical PLA by loadable AND/OR terms: - The following invention relates to the replacement of a classical PLA AND/OR terms by additional loadable PLA (LPLA) AND/OR terms:

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Loadable Programmable Logic Array

       Electronically controlled replacement of faulty AND/OR
terms of a classical PLA by loadable AND/OR terms:
- The following invention relates to the replacement of a classical
PLA AND/OR terms by additional loadable PLA (LPLA) AND/OR terms:

      Any number of the classical PLA product terms can be disabled
and any replacing number of additional loadable PLA product terms can
be implemented to match the application requirements. It does allow
minimizing the additional silicon area required by the loadable PLA
product terms.
      - The following text describes:
      - How the classical PLA AND/OR terms are disabled according to
inhibition controls.
 - How the replacement terms are loaded in an additional loadable
PLA.
 - How the two PLAs are connected together to guarantee the overall
PLA functionality.
1. Classical PLA product term inhibition (Fig. 1):
 - A set of inhibition latches is added in front of every product
term of the classical PLA. The latches corresponding to the product
terms to be disabled are set to a logical "1", either serially by
decoding the addresses of the product terms to be inhibited or in
parallel by loading the proper decoded address pattern in the
inhibition latches.
 - Each latch controls the gate of an NFET transistor, which drain is
connected to the corresponding product term match line, maintaining
it to a zero response whatever the PLA inputs are; in the same time,
it disables any stimulus to the classical PLA OR array for this same
product term.
2. Loading the replacement terms in the loadable PLA. (Fig. 2 top
part)
 - A LPLA is...