Interesting looking board. I don't know much about VLB 486 mobos, but that looks like a PC Chips style board. There's just something about it, which reminds me of these types of board. If you look at the lettering just past the keyboard socket on the PCB, PC Chips boards usually have that type of font/style of board revision identification.

I wonder if those socketed cache chips are not fake. Recently, I was testing a PCI 486 board, with some similarity to the one that you have, and found out that the chips were OK. Is it possible to populate both the 30 pin and 72 pin SIMM sockets, at the same time?

I don't know much about VLB 486 mobos, but that looks like a PC Chips style board. There's just something about it, which reminds me of these types of board. If you look at the lettering just past the keyboard socket on the PCB, PC Chips boards usually have that type of font/style of board revision identification.

I'd say you're right on the money... it seems to be an M912.

And according to the manual, it does support simultaneous use of 30-pin and 72-pin SIMMs. A bit unusual, but not unheard of.

Hey, do I see a scorch mark over there?

Kidding!! 😜

Anyway, what S3 card is that?

retro games 100 wrote:

Interesting looking board. I don't know much about VLB 486 mobos, but that looks like a PC Chips style board. There's just something about it, which reminds me of these types of board. If you look at the lettering just past the keyboard socket on the PCB, PC Chips boards usually have that type of font/style of board revision identification.

I wonder if those socketed cache chips are not fake. Recently, I was testing a PCI 486 board, with some similarity to the one that you have, and found out that the chips were OK. Is it possible to populate both the 30 pin and 72 pin SIMM sockets, at the same time?

I've never heard of socketed fake SRAM chips. From what I can tell on that tiny picture, they look real to me.

I've done some testing with 30p and 72p memory on a board of mine, and even though it's possible to use both types of memory, in my particular board, the bank with the 30p memory HAD to be the same size or larger then the 72p banks or part of the memory would not be registered in the POST.

One is a miroCRYSTAL 20SD VL, the other is Cirrus Logic CL542X.

I think the DX2 is toast, no combination of jumper settings will get it to POST. A few other things on the board get a little warm other than the CPU.

To combat this, I've bagged a BOXED PODP5V Overdrive 83Mhz off the bay!

I've never heard of socketed fake SRAM chips.

I have. In fact, there are five of them sitting on my desk, pulled from a random (and still unidentified) 486 board I have.

I just got a VLB bus board in the mail today, too. It's an Alaris with an Opti chipset and the most recent date on the Ami BIOS is 1994 but I can't find a board configured quite like this one on any of the sites with diagrams. It has 16mb RAM on it, has eight cache sockets, four of them filled but I don't know with what yet, it has a PLCC socket for an FPU and has a IIT XC87SLC-33 in it. There's another large chip next to that with a heatsink on it that I haven't identified yet. There's 5 16 bit and 3 VL Bus slots. I don't bother with boards with less than 3 VL Bus slots. Even if I don't use all three, it's nice to know they're there. It was $15 BIN so I figured I better grab it before someone else does and relists it for $300.

Tetrium wrote:

Hey, do I see a scorch mark over there? […]
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Hey, do I see a scorch mark over there?

Kidding!! 😜

Anyway, what S3 card is that?

retro games 100 wrote:

Interesting looking board. I don't know much about VLB 486 mobos, but that looks like a PC Chips style board. There's just something about it, which reminds me of these types of board. If you look at the lettering just past the keyboard socket on the PCB, PC Chips boards usually have that type of font/style of board revision identification.

I wonder if those socketed cache chips are not fake. Recently, I was testing a PCI 486 board, with some similarity to the one that you have, and found out that the chips were OK. Is it possible to populate both the 30 pin and 72 pin SIMM sockets, at the same time?

I've never heard of socketed fake SRAM chips. From what I can tell on that tiny picture, they look real to me.

I've done some testing with 30p and 72p memory on a board of mine, and even though it's possible to use both types of memory, in my particular board, the bank with the 30p memory HAD to be the same size or larger then the 72p banks or part of the memory would not be registered in the POST.

PC Chips used fake cache memory chips. The best way to tell is to follow the traces and see if they actually connect up to anything. If there's no traces leading from the cache sockets to anything else on the motherboard or if the traces terminate before they come into contact with any other components then they're fake.

Well... after another play with the jumpers and flipping around the cpu in the socket... I think I can safely certify it dead 🤣

Now to wait for the 83Mhz Overdrive to show up, at least I won't be able to put that in the socket the wrong way around 😁

sliderider wrote:

PC Chips used fake cache memory chips. The best way to tell is to follow the traces and see if they actually connect up to anything. If there's no traces leading from the cache sockets to anything else on the motherboard or if the traces terminate before they come into contact with any other components then they're fake.

I'm aware of all this, but usually those fake cache chips will be soldered directly to the board. Never heard of those fakers being the full package before, thats all 😉

Very nice, looking forward to the finished product!

That board is toast, rather than the CPU!

This is why....

Its taken a whack at some point in its life - this was probably the cause of the "crackle" I got when I first powered it on, rather than the incorrect bus speed jumpers.

Oh well, back to the drawing board, and some rather expensive 3-slot VLB boards on ebay! 😒

PeteUK wrote:

Voila! :happyhappy: […]
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Voila! 😁

It's gonna be a long day... I think that CPU went *crackle* when powered on... partly due to the previous owner setting all the jumpers wrong, and me not knowing as I haven't touched a 486 in 10 years 🤣

Oh, and I believe the CPU is the wrong way around in that pic...

Latest...

M912 AT Motherboard *DEAD* To be replaced with SOYO SY-25M/N/P
TI 486DX2-80
4x 1Mb 30Pin SIMMS, 2x 8Mb 72Pin SIMMS
miroCRYSTAL 20SD VL
Cirrus Logic CL542X