RE: In search of bad 4164, 41256 DRAM

From: Jeffrey Birt <birt_j_at_soigeneris.com>
Date: Sun, 13 Oct 2019 08:34:43 -0500
Message-ID: <002101d581ca$f9964750$ecc2d5f0$_at_soigeneris.com>
>>Yes, if 2 cells next to each other get shorted together for whatever reason >>you will not find them if you fill the whole DRAM with zeros or ones.

>>But even 0x55 and 0xAA won't find all possible faults. Grab memtest86+ >>and take a look at all the patters it uses (it tells you while it's running).

I have looked at a few test programs like this and they are written with multi-bit wide memory in mind. When testing a single bit wide DRAM most of these tests will not yield any benefit (I think) as the tests are designed to alternately set adjacent bits by using a variety of strategies which one can do directly when testing a single DRAM chip. 

One thing that caught my eye in the explanations of test for memtest86+ was the walking ones test which might be useful so I'll ad that test in and see what happens.

Jeff Birt
Received on 2020-05-29 23:04:24

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