M571 retro PC

I bought an old junk PC from a scrap collector on the street. I did it for nostalgic reasons, it reminds me of my first PC.

Elpina BA E-VO motherboard in AT case

A few days ago I saw a truck full of old junk computers, printers and CRT monitors. On an impulse, I spoke to driver and offered 10$ for a PC that looked least damaged. It was in a AT mid-tower case, so I knew we’re talking 1994-1996 era. I took it home and tried to start it, but it didn’t work. It would spin CPU fan and turn all the lights on (power, turbo, hdd), but it would not react to keyboard, output anything or beep if I pulled memory. After a few minutes of trying to make it run it started smelling of mold. I took it apart and left pieces out on the balcony under direct sunlight. After 6 hours of baking, I hooked up motherboard to a known good power supply and it booted to post screen!

I only found “Elpina” and “BA E-VO” in silk screen. This was enough to find a forum post about it being a relabeled PCChips M571 motherboard. In late 90-s to early 2000-s, PCChips was a very prolific motherboard vendor. It was offering very cheap prices and their motherboards sort of worked, but not very well. I did search online and found a couple of very comprehensive support sites for M571: m571.com and cwcyrix. Thanks a lot to people who created and maintain those pages! If it wasn’t for them, I’d give up and just desolder power, SIMM-72 and battery sockets and recycle the rest. Apparently there are 3 main versions of this motherboard. Version 1.x have 4 ISA slots and no on-board sound. Versions 3.2, 3.2A and 7.x have 3 ISA slots and on-board C-Media CMI8330A sound chip. Version 3.2A and 7.x support 2.2v core voltage for AMD K6-2/K6-III CPUs, and it’s clearly marked with a black dot next to 2.2v jumper. On versions 1.x and 3.2, same jumper is clearly labeled as 2.5v. This led me to believe I got version 3.2.

I replaced 32MB DIMM that came with PC with two speedy 64MB PC-133 DIMMs for a total of 128MB of RAM.

Once I booted, the CPU was mis-identified. It is a Pentium MMX 200MHz, configured as 66MHz FSB and 3x multiplier. It was showing 225, 233, 250 and 266 randomly on each boot.

Post from M571 3.2 motherboard BIOS version 19971120S

This got temporarily fixed once I switched from on-board VGA to Diamond Stealth 2000 PCI VGA card. It was showing correct Pentium MMX 200 for a while, but later switched to 233 on it’s own and stays put for now. It got fixed again once I’ve added 3COM 3C905 PCI network card. Could it be that high quality capacitors on add-on cards make mainboard more stable? I didn’t find out definite root cause yet.

This PC belonged to a Tamil christian church, was last used around 2002 and had WordPerfect 9, Quattro Pro 9 and Corel Draw 7 on it. It also had bloat in form of Norton Antivirus 2002 and AOL, so I did clean re-install of Windows 98 SE. Floppy drive wouldn’t accept floppy disks, so I had it replaced. Later I disassembled it to find hair and a bunch of used long distance calling cards. I cleaned floppy drive thoroughly, and it now works fine and is back in this PC.

I decided to update to a more recent version of BIOS. I couldn’t flash BIOS with amiflash 6.x that came from PCChips with BIOS file, it would just hang. While looking for different versions of amiflash, I came across an amazing project: UniFlash.

Uniflash 1.40 in action

This program worked beautifully, I took backup of BIOS that motherboard came with and upgraded to unofficial BIOS version 19990514S-J1. It is based on last official BIOS version 19990514S from PCChips. It unlocks a few performance settings, updates on-board VGA BIOS and adds AMD K6-2/K6-III support. Original 19990514S BIOS also bumped the maximum HDD size from 8 to 32GB.

Post from M571 3.2 motherboard BIOS version 19990514S-J1

The one the motherboard came with was 19971120S. It is older then any M571 3.2 BIOS versions I found online. One of the things it doesn’t do that later versions do well is booting from CD. If anyone is curious to look at it, here is the file: 2016-05-13-m571-19971120S.zip.

I replaced Seagate ST32132A 2GB 4500 RPM HDD with Seagate ST315323A 15.3GB 5200 RPM HDD, and it works fine. I also tried using a Seagate ST330630A 30.6GB 7200 RPM HDD. It works great, but is very noisy and runs very hot.

I’m kind of tired of this project for now, so I’ll just put it on hold until I have some free time and willpower to continue. Once I get back to it, I’d like to recap the board, add 2.2v voltage support and run it with AMD K6-2+ 366 CPU.