Browse Prior Art Database

Read Only Programmable Logic Array With Writable Segment

IP.com Disclosure Number: IPCOM000083018D
Original Publication Date: 1975-Mar-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Jones, JW: AUTHOR [+2]

Abstract

The inclusion of a small writable array 10 a Programmable Logic Array (PLA) made up of read-only search and read arrays 12 and 14, permits any word in the read-only arrays to be changed. An input argument that selects a word in the search array 12 is also caused to select a word in the small writable array 10. The read array portion of the writable array is made to produce an output, which when exclusive OR'ed with the incorrect output from read array 14 produces the correct output. Thus a few writable words in an otherwise all read-only programmable logic array, provides great flexibility in handling engineering changes.

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Read Only Programmable Logic Array With Writable Segment

The inclusion of a small writable array 10 a Programmable Logic Array (PLA) made up of read-only search and read arrays 12 and 14, permits any word in the read-only arrays to be changed. An input argument that selects a word in the search array 12 is also caused to select a word in the small writable array 10. The read array portion of the writable array is made to produce an output, which when exclusive OR'ed with the incorrect output from read array 14 produces the correct output. Thus a few writable words in an otherwise all read-only programmable logic array, provides great flexibility in handling engineering changes.

In addition, the writable array may be used to provide a synchronizing pulse to an oscilloscope, not shown. The writable search array 10 would have a pattern stored in one of its words, which would be selected by the input argument of interest. The selected word would cause a pulse to appear on an output pin of the array to trigger the sweep of the oscilloscope, so that subsequent signals in the system could be viewed.

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