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I've got an old 386 laptop - specifically an OmniBook 300 - and I'm a little suspicious of the RAM. It's exhibited some very odd symptoms, such as memory-related crashes and boot failures, so I'd like to give it a thorough testing. It has 2 MB of RAM built in, plus an additional 6 MB on a Kingston memory module that looks a little bit like a small compact flash card that's just a bare PCB (3 DRAM chips and some capacitors).

The computer boots from ROM, so I don't have the option of using any kind of testing boot disk. It would have to be something that can be run from MS-DOS 5.0.

What software exists for thoroughly testing memory on a system like this?

  • 3
    memtest86 would be ideal, but I don't know if you can start it from MS-DOS. – Ross Ridge May 29 '18 at 23:40
  • @RossRidge - memtest86 is multiboot compliant (i.e. it is bootable from all standard linux boot loaders), so can be used via LOADLIN. – Jules May 31 '18 at 0:11
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The Omnibook has its own self-test which can be run by pressing Esc when powering it up.

The best freely-available general-purpose memory checker is Memtest86+, and older versions are available as plain DOS executables (look for “Download - Pre-Compiled EXE file (Pure DOS - Obsolete)”). They are identified as obsolete but should be fine for your purposes; note however that version 4.10 might be the last one you can run on a 386, more recent versions apparently fail. As mentioned by Jules, you should also be able to “boot” the pre-compiled bootable Memtest86+ binaries using loadlin.

Another tool worth looking at is Craig Hart’s PC Diagnostics ’95 which includes decent memory tests. His Testmem is a dedicated memory tester that also works well but only tests extended memory.

  • Ha, somehow I completely overlooked the built-in self test feature despite reading the service manual plenty of times in the years that I've owned the computer. Looks like the Memtest86+ v2 series pure DOS versions will do what I want, though whether or not they run on a 386 remains to be seen. The built-in test is giving it a clean bill of health so far, at least. – db2 May 30 '18 at 11:31
  • Can you tell if the built-in test is actually checking the RAM on the Kingston module? I wouldn't be totally shocked if it didn't. – Michael Kohne May 30 '18 at 12:21
  • If this machine has a removable ROM, one might be able to make a memtest EPROM :) – rackandboneman May 30 '18 at 12:21
  • @MichaelKohne I think it is, because it runs for a few minutes and reports 8 MB OK. – db2 May 30 '18 at 13:09
  • @rackandboneman It does! The ROM is actually a PCMCIA card with DOS 5.0 and Windows 3.1 burned into it (mostly execute-in-place, with an MS Flash Filesystem driver for a small D: partition with support files). I'm running a custom-made linear flash card with an updated ROM image on it. (And the self test for that reported a checksum match.) – db2 May 30 '18 at 13:12

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