Browse Prior Art Database

Diagnostics for Font Read-Only Store

IP.com Disclosure Number: IPCOM000044009D
Original Publication Date: 1984-Oct-01
Included in the Prior Art Database: 2005-Feb-05
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Elstner, J: AUTHOR [+2]

Abstract

This article describes a technique for obtaining the physical defect location on a single serial I/O 16KX8 read-only memory, in order to make failure analysis possible. The fact that this product uses a single I/O and a rather sophisticated mechanism for decoding address inputs makes finding the physical defect location difficult. The array consists of 131072 FET transistors which are either depletion or enhancement devices, depending on the ion implant personalization mask. The beginning of the procedure consists of using a bench tester which localizes electrically the failing address(es) and the defective data bit(s) by comparison with a reference device. These data are put into a basic program which indexes the location in the personalization data set and gives the cell and the row numbers in the array.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 91% of the total text.

Page 1 of 1

Diagnostics for Font Read-Only Store

This article describes a technique for obtaining the physical defect location on a single serial I/O 16KX8 read-only memory, in order to make failure analysis possible. The fact that this product uses a single I/O and a rather sophisticated mechanism for decoding address inputs makes finding the physical defect location difficult. The array consists of 131072 FET transistors which are either depletion or enhancement devices, depending on the ion implant personalization mask. The beginning of the procedure consists of using a bench tester which localizes electrically the failing address(es) and the defective data bit(s) by comparison with a reference device. These data are put into a basic program which indexes the location in the personalization data set and gives the cell and the row numbers in the array. It also allows for the test validation. The coordinates are entered in the main computer where resides the graphic unpersonalized data set, in order to obtain the index of the defective cell in the file. It should be mentioned that the unpersonalized data provide 131072 depletion devices and the personalization operation consists of erasing the ion implant on certain devices, depending on the part number. The purpose of the next operation is to find the index in the personalization data set. If found, the defect is on a depletion device, and on an enhancement device, if not found. At last, operation on the basic program will...