Memtest86+ 5.01 crashing on Pentium \ VOGONS

Memtest86+ 5.01 crashing on Pentium

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First post, by auron

Posted on 2024-07-09, 19:26

auron Offline

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Posts: 994
Joined: 2015-08-20, 01:56

when i go to run memtest86+ on a pentium, using a boot floppy created as per the instructions, the tool instantly crashes with an out of range message on the monitor. my first thought was that it's trying to use 686 instructions, but on the site it says that it should run on pentium and up. can anybody confirm that memtest86+ does run on pentiums? memtest86 does run fine, forgot which version of that i have but should be the newest.

assuming that memtest86+ is supposed to run fine, that would put my floppy at fault, which i didn't create really all that long ago. it's one of those very late verbatim ones bought new sometime in the 2010s and i'm unclear as far as their reliability goes. is there a tool out there that can verify a floppy against a .bin image?

Reply 1 of 2, by rasz_pl

Posted on 2024-07-10, 04:34

rasz_pl Offline

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try older version just to be sure, there was 4.something that even ran on 486

https://github.com/raszpl/FIC-486-GAC-2-Cache-Module for AT&T Globalyst
https://github.com/raszpl/386RC-16 memory board
https://github.com/raszpl/440BX Reference Design adapted to Kicad
https://github.com/raszpl/Zenith_ZBIOS MFM-300 Monitor

Reply 2 of 2, by jtchip

Posted on 2024-07-14, 00:20

jtchip Offline

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Joined: 2019-06-17, 22:24

There are screenshots of various users running memtest86+ >=6.0 on i586-class CPUs (an AMD K6-2, SiS 550, Intel Pentium and Pentium MMX), and even an Am486DX4, so it definitely works on Pentiums.
I have used memtest86+ 6.20 on a Pentium MMX and a K6-2+ (both only support the i586 instruction set), the former running memtest86.bin via GRUB4DOS on MS-DOS 7.10 (Win98SE without the GUI) and the latter via PXE from the boot rom of a 3Com 3C905C, with the TFTP server serving pxelinux from syslinux 6.04.
I have just tried the latter again with the latest 7.00 release and it still works. I avoid using floppies if possible because they're a hassle.
When you say you say "using a boot floppy created as per the instructions", which instructions are those? The only mention of floppies on the main page is "If you need a floppy image, use the "make iso" command to generate a 'floppy.img' file" but the binary files, specifically memtest32.bin from the binaries, should just work written directly to a floppy. On Linux this would just be:

1dd if=memtest32.bin of=/dev/fd0 oflag=direct status=progress

There is a floppy.img make target but that justs writes memtest32.bin into floppy.img and pads that with 0s to 1440KiB.
The fact that your monitor went out-of-sync suggests something wrong with the binary that was written to the floppy as memtest86+ only uses text mode.

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