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Random-Access Memory Diagnostic

IP.com Disclosure Number: IPCOM000059788D
Original Publication Date: 1986-Jan-01
Included in the Prior Art Database: 2005-Mar-08
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Burkes, PB: AUTHOR

Abstract

The present diagnostic will test a non-contiguous random-access memory (RAM) subsystem which provides functional verification of addressability, data bus lines and parity logic without the need for checking each non- contiguous segment separately. The present diagnostic can be used on both contiguous and non-contiguous RAM systems. The test sequence for the diagnostic of the present invention is as follows: 1. Test the RAM logic at the beginning of each RAM section to: a) verify that an even and odd parity word ('A55A' and 'A55B') can be written and read back on both even and odd boundaries, and b) verify that an even and odd parity byte ('5A' and '5B') can be written and read back on both even and odd boundaries. 2.

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Random-Access Memory Diagnostic

The present diagnostic will test a non-contiguous random-access memory (RAM) subsystem which provides functional verification of addressability, data bus lines and parity logic without the need for checking each non- contiguous segment separately. The present diagnostic can be used on both contiguous and non-contiguous RAM systems. The test sequence for the diagnostic of the present invention is as follows: 1. Test the RAM logic at the beginning of each RAM section to: a) verify that an even and odd parity word ('A55A' and 'A55B') can be written and read back on both even and odd boundaries, and b) verify that an even and odd parity byte ('5A' and '5B') can be written and read back on both even and odd boundaries. 2. Determine the amount of memory available beginning at the first segment of each section by doing the following: a) at the first word of each 64K segment of memory, perform a "walking 1's" test to verify that no shorts or opens exist on the data lines, b) fill the 64K segment with the pattern 'CCCC', c) go to the next segment, and d) repeat steps a-c for all remaining segments, or when the end of memory is found in the last section. 3. Starting at the beginning of memory, compare the first word with 'CCCC'. If it compares, then write the word with '3333'. Compare the word with '3333'. If it compares, then go to the next word in the segment, and repeat for all remaining words in the segment. 4. Repeat step 3 for all rema...