You say that the BIOS POST display incorrectly reports the type and speed of your processor, before and also after you replaced your cache chips. I have seen a BIOS POST display message saying "bad cache" on this exact board, if I attempt to overclock it too much, by setting the mobo's speed timing jumpers too aggressively.

However, if you have put 8 "IS61C256A-15N" cache chips in to cache banks 0 and 1, you will also need to replace the existing factory supplied TAG chip with one of these "IS61C256A-15N" cache chips. So, you really need 9 "IS61C256A-15N" chips to successfully upgrade this board's cache from 128Kb to 256Kb: 8 for the cache banks, and 1 for the TAG socket.

Also, check to ensure that the orientation of your cache chips is correct.

Edit: corrected a copy-and-paste mistake.

Swap out that M5M5178BP chip for another 61C256. In other words, you need nine 61256 chips in total, eight for the cache and one for the TAG. With 128K cache, the board only needed an 8Kx8 TAG chip (which is what the M5M5178BP is), but for 256K cache you need a 32Kx8 TAG.

@RG100. Yes BIOSPOST does display incorrectly type and speed of this AMD 40Mhz processor before and after replacing the cache chips. I didnt change anything on the jumpers. Maybe that the problem for the processor.. Iam not that familiar to build with 386 stuff.. I know how to place addons card. But not with the motherboard settings.
EDIT: I have checked the jumper config, but thats stock for the 386 processor. The oci is an KoYO 80 mhz.. Dunno if that is standard.
I read this in the manual about the cache chips.. 64K and 128k using an 8k8 TAG chip. 256K need an 32k8 cache chip..

Does somebody know the Part no for that 32k8 TAG chip? Or where i can search for.

Ok its fixed now.. Did remove the TAG chip en replace it with on old cache chip..

Its says now: 256MB cache 40 Mhz CPU clock..

Only where can i find an new 32k8 cache chip for it?

Old Thrashbarg has summarised what you need to do. (I said the same thing, but I made a bit of a mess of it with a copy-and-paste error, which I have now edited.)

Basically, you remove the existing factory supplied TAG cache chip on the board, and replace it with exactly the same kind of cache chip that you have used to fill up the 8 cache sockets.

Does somebody know the Part no for that 32k8 TAG chip? Or where i can search for.

Perhaps you should re-read the two posts above yours. Use another 61C256 chip as the TAG. You know, like the 8 61C256 chips you installed for cache? You need another one. For a total of nine. Put the ninth one in the TAG socket. 😒

M5M5178BP-15 is this the same chip as the 61C256?

I know that the first is an 8k8..

Why didnt the manufacturer use the same ISSI chip as TAG as for the cache? And using an M5M5178BP for this?

The M5M5178BP is an 8kx8 chip. They used it as TAG because the 128K cache configuration called for an 8kx8 chip. They did not use a 61C256 because that's a 32kx8 chip and they needed an 8kx8 chip.

But now that you've upgraded the cache you need a 32kx8 TAG chip. So you need to replace the M5M5178BP, which is an 8kx8 chip, with a 61C256, which is a 32kx8 chip.

Ok thank you all, its solved..

Only have to wait on my new AT case and then i can build my new 386 system. 😁

Robin4 wrote:

Ok thank you all, its solved..

Only have to wait on my new AT case and then i can build my new 386 system. 😁

Cool 😉

Where did you manage to find an AT case btw? Local find?

Edit: And do take pics! 😁

Tetrium wrote:

Cool ;) […]
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Robin4 wrote:

Ok thank you all, its solved..

Only have to wait on my new AT case and then i can build my new 386 system. 😁

Cool 😉

Where did you manage to find an AT case btw? Local find?

Edit: And do take pics! 😁

For my AMD k6 Rig i find it on marktplaats.nl
There i bought also my first AT case new, but its to small for my.
I searched a lot on marktplaats, but an AT case is very hard to get..
For my 386 rig ive bought one on ebay.. Yes shipping was very expensive, but i find it worth to spend more on a new case..

I love to have a `clean` build.

It has the vintage display..

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem … em=390211900047

That seller has more AT cases, but they are to expensive and to big for me.

Robin4 wrote:

For my AMD k6 Rig i find it on marktplaats.nl There i bought also my first AT case new, but its to small for my. I searched a lo […]
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Tetrium wrote:

Cool ;) […]
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Robin4 wrote:

Ok thank you all, its solved..

Only have to wait on my new AT case and then i can build my new 386 system. 😁

Cool 😉

Where did you manage to find an AT case btw? Local find?

Edit: And do take pics! 😁

For my AMD k6 Rig i find it on marktplaats.nl
There i bought also my first AT case new, but its to small for my.
I searched a lot on marktplaats, but an AT case is very hard to get..
For my 386 rig ive bought one on ebay.. Yes shipping was very expensive, but i find it worth to spend more on a new case..

I love to have a `clean` build.

It has the vintage display..

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem … em=390211900047

That seller has more AT cases, but they are to expensive and to big for me.

That case looks awesome!!

How much did shipping set you back btw?

$89.80 USPS Priority Mail International (shipping only) (i think this is included taxes) But it comes from the USA..
If you calculate the full price, its about 87 euros.. Its expensive i know. But then you have an brand new case.. Not Yellowed, and with all stuff in the box..

I wish people would sell that good vintage stuff in Europe 🙁
The nicest cases, the backplates, the best AT2ATX PSU adapters, all from the USA. I don't mind one bit though, except shipping is so expensive!

Hey Robin4, post some pics after you're done, alright?

Btw, does your case also come with those white plastic standoffs? I reckon those are hard to find these days so I hope you already got those.
And cheers for the tip marktplaats.nl. I look there very occasionally (don't even have an account there 🤣, and not having a drivers license doesn't help either, I need to ask my mum if I need to cover a longer distance 😜) and from time to time something nice passes by.

I also noticed sooo many people looking for "old useless broken 286,386,486 etc etc", Heck, they even pick that old junk up for free...L O L!

You wont find almost anything in this area (Netherlands , belgium, germany) Sometimes you have may be lucky if you find something here..
Most of the stuff i buy from the USA.. and sometimes iam looking in the UK.

I was thinking of selling AT stuff if there was more intressing.. If it was easy to selling those stuff ( if there was an market for) then it was easy to start..
But soon i will selling my own case that iam using for now till the new one arrives. Bought that case also new in box from marktplaats.nl the only con is that the PSU is dead (was a cheap thing that wouldnt last long) Yes new cases comming with standoffs.

The dutch stores i could recommend are abgcomputer or lcs~automation they sell some of that older stuff as new..

Yes i will make some pictures if i can begin to build my 386 build.. Then i will start to build my AMD K6 systeem, but have to clean the front first (try to was that yellowed stuff off ) (ill try it with quick n brite)

Most of that computers 286, 386, 486 will be collected for old schred.. (now days you could earn on old iron)

I hope i may kick this topic up again? (because off some follow up questions, because iam consider it to use it in my previous purchased mini tower case)

There is nothing wrong with this board and i finished with the cache ram installed correctly to 256KB in 2011.

Only my main concern is.. I think that iam dont going to use more memory as 8MB (think its more enough for a 386 machine), so make it any sense why i install 256Kb of cache on this board (what was before 128Kb)

And for the already owners of this motherboard, how does this board perform? Is it a bad performer, is it a good performer? Or maybe in between?

What are the PROs of this motherboard? And what are the Cons?

I bought this board (as you may see, or you may have followed my adventure in the couple of years.) iam guessing in 2011.. And since then i have keept it stocked in a antistatic bag and in a sturdy cardboard box..

Now i was looking for a 386 board and on my eye that contaq 386 is almost the best i have.. I also have to Forex motherboards.. But the simm socket are in a very strang way that it would block very longer ISA card.
So iam guess because the memory is on the right bottom on the forex board, it was a better idea to look for a board where the memory banks are on the upper side of the board..
In that new tower case i have to flip the board around. So the lowest slots would end-up on the higher part of the case.. And the memory banks would end up on the lower part of the case.

Here's a documentation for your motherboard here : http://www.win3x.org/uh19/motherboard/show/1391

If you can help us with a few things (a photo and a BIOS dump would be perfect !)

Having 256KB of cache instead of 128KB may improve the performance slightly, but it's going to be very very minimal.

This board looks like a good board, now of course looks doesn't always mean performance. For that maybe you could benchmark it to compare it with many 386s that have been benchmarked here ? Post your 386 Speedsys results here

Nice website of documentary you have made! Looking very nice.. Yes i can help later on.

Deksor wrote on 2020-09-01, 22:20:

Here's a documentation for your motherboard here : http://www.win3x.org/uh19/motherboard/show/1391 […]
Show full quote

Here's a documentation for your motherboard here : http://www.win3x.org/uh19/motherboard/show/1391

If you can help us with a few things (a photo and a BIOS dump would be perfect !)

Having 256KB of cache instead of 128KB may improve the performance slightly, but it's going to be very very minimal.

This board looks like a good board, now of course looks doesn't always mean performance. For that maybe you could benchmark it to compare it with many 386s that have been benchmarked here ? Post your 386 Speedsys results here

Hi

here is the bios for this motherboard. Its using an NM27C512Q eprom.

It made me laugh that i started this topic about 10 years ago. Time gets fast when getting older.

I've got a Contaq 486 ISA motherboard, with an 82C591 chipset. On mine, the pads for the 16Kx4 dirty TAG were present but not populated, and there wasn't even a silkscreen for it. I added a socket and appropriate 16Kx4 SRAM to it, and that really woke up its off-cache RAM access. It's still a pedestrian board at best, but I'll take 53MB/sec memory bandwidth (SpeedSys) over 25-ish any day.

On the plus side it's rock solid with a fan-cooled DX-50 (though the board isn't quite fast enough to let that chip stretch its legs fully) and the MR BIOS I found works great!