Just the memory is probably worth more than $35. And the cpu probably goes for $15 by itself. So it seems to be a very good deal, assuming it works. Can't tell from the photo, but the condition of the barrel battery could be a deal-breaker. It doesn't *seem* like it's leaking from the blurry pic, but who knows?

No VLB slots is a bit of a bummer, and maybe a hint that it's maxed out at 33Mhz?

Cache slots are full, which is good. But sometimes these systems have fake cache, and again, can't tell from the pic.

If the $35 is not a hardship for you, then I'd take the chance on it. But maybe you could get clearer photos or questions answered before you buy?

You can always replace the cpu with DX2 - ie DX2-66 or even 80 if the board supports 40MHz FSB. With voltage converter adapter you can use even up to DX4-133/160MHz cpus. But as it only has ISA slots, VGA performance will suffer.

The seller doesn't seem to know much about the motherboard when I asked him earlier. He did say that the battery doesn't appear to be leaking and when I asked him about the cpu and what model the motherboard is, he just replied what text is on the cpu.

A80486DX-33
L2526281
SX419

Isa-only would be a deal breaker for me, a 486 really needs a VLB vga IMHO

Well, if you once had an early 486 and want to stay period correct, VLB is not an option. I'm thinking building plain 486 myself.

I bought it. In the end I got it real cheap. I paid $32 it and that includes shipping. If the motherboard isn't good, at least I get the memory modules and the cpu, so I don't think it was a big risk.

Baoran wrote:

I bought it. In the end I got it real cheap. I paid $32 it and that includes shipping. If the motherboard isn't good, at least I get the memory modules and the cpu, so I don't think it was a big risk.

Exactly. That memory and cpu can be used in a different 486 board if necessary, and you got them for less than if you were to buy them straight. Well done, keep us posted on how the board works!

I finally received the motherboard today. I removed the leaky battery and took couple non-blurry photos of it.

There are few things I noticed. The power connector on the motherboard isn't straight, but it might have been like that when it has been manufactured. There is also a jumper in middle of the connector next to where the battery was that is suppose to external battery connector.
There is M423 Rev 1.2 writen on the motherboard, so the motherboard seems to be this one: http://stason.org/TULARC/pc/motherboards/I/IL … -486-M-423.html

As you can see from the bottom picture, the motherboard isn't straight. Is there any way to straighten it without causing it damage?

I don't think you have to worry about straightening it. If you mount it in a case that is in good shape, use proper standoffs, and screw it down, it should be OK.

If the cache ships are not fake, I should have 256Kb cache
Should I remove the jumper that the previous owner has put in that external battery connector?
Based on that manual that I linked, it says that you can't put faster than 50Mhz DX2 cpu on the motherboard, which is kind of disappointing. I might have been interested in trying that 80Mhz Cyrix that I got with another motherboard because that motherboard is much more corroded than this one.

Baoran wrote:

If the cache ships are not fake, I should have 256Kb cache
Should I remove the jumper that the previous owner has put in that external battery connector?
Based on that manual that I linked, it says that you can't put faster than 50Mhz DX2 cpu on the motherboard, which is kind of disappointing. I might have been interested in trying that 80Mhz Cyrix that I got with another motherboard because that motherboard is much more corroded than this one.

The manual might be outdated. If your board supports 33MHz FSB (which it seems to be able to do), it might also support the 5v DX2-66.

As you already know, it's a really early 486 board, it's probably gonna be kinda similar to a top-range 386 board.

If your Cyrix works in it, why not run it at 2x33MHz? It should at least be a step-up 😀

Thanks. Perhaps I will try. It has a bit strange ram configuration. In bank 0 there seems to 4 normal 1mb modules but in bank 1 it seems to have 256Kb modules that say "laser printer memory x4" on the chips.
It probably isn't one of the earliest 486 motherboard, because it seems to have been manufactured in 1992.

I have three of those M423 boards. some features and configuration options are quite strange. What is this 7-pin "weitek 4167" connector about? The board offers two Opti local bus slots, but I get no vga output with an Et4000 loca bus vga card . I guess my card might be a non working one. Am5x86 with voltage adapter is not working (reboots after memory count)

Baoran wrote on 2017-05-03, 22:19:

I finally received the motherboard today. I removed the leaky battery and took couple non-blurry photos of it.

Do you still have this board ? And if so, could you make a BIOS dump ? I'm trying to identify the chipset and a BIOS image would be very useful.

http://www.win3x.org/uh19/motherboard/show/3068