That board uses the same standard 32Kx8 cache chips as just about every other 486 board. That's what the 61256 is. You can find the 15ns variants on eBay fairly frequently.

Looks indeed like a 15ns chip.

The board itself looks like one of the really useful ones. It even has PS/2!
SiS chipset is one of the best ones also.

About the cache, you can put standard cache chips in there. Theres generally 3 ways to get these cache chips:
*Buy the cache chips
*Buy a (crappy) board which has cache chips and cannibalize those
*Get one of your other 486 boards, wipe off the dust and cannibalize it's cache chips.

That board, if it still works, is definitely a keeper 😉

Thanks for the advice. 😀
I checked my other boards already and they have different chips (32pin vs the 28pin if I counted correctly) and the other board is a 286 the size of an aircraft carrier with everything soldered on.
Btw the only difference that I saw from the one in the picture is that mine actually has an AT style connector, but it says "EXT PS/2 Mouse" by the set of pins beside the AT port. Does this mean that the board itself is compatible with PS/2 and I would just have to replace the AT port? I've never switched vintage ports around so this may sound like a dumb question to you but I honestly don't know the answer.

Does this mean that the board itself is compatible with PS/2 and I would just have to replace the AT port?

No... if you want to use a PS/2 mouse, you plug a PS/2 mouse port into the PS/2 header. This was discussed quite recently. If you want to use a PS/2 keyboard as well, you need to get an AT->PS/2 adapter.

Fortunatly I have several AT keyboards (some probably still work) in my closets, although the PS/2 is faster but it's not the end of the world.
There is a CPU sitting in the socket too, but the fan is glued onto it so I can't tell for sure what it is til I fire it up... It says "PABMDCB" and "2XCLK" on the bottom side of the chip. Pretty sure those were the Intel (maybe AMD?) DX2 66 chips. 😖

PS/2 keyboards are not "faster". PS/2 keyboards are the same as AT keyboards, just with a different connector on the cord.

Old Thrashbarg wrote:

PS/2 keyboards are not "faster". PS/2 keyboards are the same as AT keyboards, just with a different connector on the cord.

I was refering to AT keyboards not being able to handle more than a couple keys being pressed at once, 🙁 while I've never had that problem with PS/2... unless there was something else wrong with the computer/keyboard that I didn't know about. 😖
Either way I guess I worded that wrong. I send my sincere apologies to the internet. 😢

nemesis wrote:

I was refering to AT keyboards not being able to handle more than a couple keys being pressed at once

To repeat Thrashbarg: PS/2 keyboards are the same as AT keyboards, just with a different connector on the cord.

A PS/2 to AT adaptor is purely a mechanical adaptor, there are no electronics inside one at all. If you were having issues with key ghosting or multiple presses not registering, the blame is with the keyboard matrix, not the connector or the controller inside the computer.

(Forgive me for getting off topic a little here) Ok. I understand that the keyboards are identical right up to but not including the connector shape (and possibly the number of keys on it depending on which particular board you happen to have). And if I understand, both are a serial connection with the bus operating at as much as 16kHz.
When I was a kid I used 10 - 15 different machines with AT connection keyboards... all of which would lock up for a second and beep if I pressed more than 1 button at a time with the exception of the "shift" key + most other keys (just establishing that this was a very common problem for me, hence my frusteration with AT).
I really don't want to run into this issue again so if you can clear up my confusion (as you already may have noticed, I only know the very basics of the workings of vintage computers), what do you mean by the "keyboard matrix"? Is that the actual connections inside the keyboard itself?
If so then it was just a problem of low quality keyboards... if not then I just feel dumb. 🤣

EDIT: I just did some more research on it and it looks like I've just had really really bad luck with AT keyboards.: 😢
All this time I've been blaming the style and it was just shoddy workmanship 🤣 . On the other hand I've never had a problem with a PS/2 keyboard so I guess I should be happy about that. 😁

nemesis wrote:

I really don't want to run into this issue again so if you can clear up my confusion, what do you mean by the "keyboard matrix"? Is that the actual connections inside the keyboard itself?

Pretty much. Electronically, the keys on your keyboard are arranged into a 2-dimensional grid, but physically this grid is twisted and folded up to suit the layout of the keys.

Since you will always have a number of keys serviced by a given "row" or "column" of the encoder, it's impossible to use more than a certain number of keys at once.

Which keys, and the number of keys will vary from keyboard to keyboard, totally independent of the connector on the end of the cable.

EDIT: I just did some more research on it and it looks like I've just had really really bad luck with AT keyboards.: 😢
All this time I've been blaming the style and it was just shoddy workmanship 🤣 . On the other hand I've never had a problem with a PS/2 keyboard so I guess I should be happy about that. 😁

Yeah. If you attach your PS/2 keyboard to a computer with a PS/2 to AT adaptor, you will have the same results as you do using a computer with a PS/2 connector.

I use PS/2 keyboards on AT motherboards all the time, works fine 😀

This is why I love this place.
Anyway, I bought some 15ns cache chips from ebay (hope they work) for ~$5 w/shipping... cheaper than the others 😀 . Also ordered a ps/2 mouse port and ps/2 keyboard adapter just in case.

nemesis wrote:

This is why I love this place.
Anyway, I bought some 15ns cache chips from ebay (hope they work) for ~$5 w/shipping... cheaper than the others 😀 . Also ordered a ps/2 mouse port and ps/2 keyboard adapter just in case.

Just remember that there were several different PS/2 mouse adapters made, they are not compatible.

Yeah, I'm hoping it's the right one. The pins seem to line up with the holes so that's a good sign I guess. If it doesn't work, at least I didn't spend very much money on it. 😖

you can always repin the connector to match the motherboard

TheMAN wrote:

you can always repin the connector to match the motherboard

I was kinda wondering about that. I should be able to get the correct mapping for the motherboard somewhere on the wonderful web.

I have a couple new questions about this build as I wait for the parts to arrive.
1. Will an EIDE drive make any difference installed on a 486 mobo vs an IDE?
2. If I choose to use an adapter and use a CF card instead, are there any known issues?