It certainly appears to be a battery header. Have you got a multimeter to trace paths with?

As far as identifying boards, sometimes the BIOS string is the only way.

Certain that is a battery header. Probably a 4.5V Rayovac

Thanks, guys. Success!

One side of the header goes to a diode on the motherboard, so assuming that was positive, I metered the other side to the ground pads (and negative from the clipped battery).

So far, so good. I don't have to keep re-entering my damn HDD settings 😀

Now I just need to understand why this only see maximum 6mb (minus 384k for some reason) of ram. Even with 8x1mb sticks, or 4x1mb + 4x4mb sticks... it maxes out at 5760k. Should be enough for me anyway.

I'd remove the battery before it starts leaking on your board.

It is removed. You can kinda see in my last pic (the glue is still on the board).

And yeah, it had JUST started leaking, so that advice is always golden 😀

probnot wrote:

Now I just need to understand why this only see maximum 6mb (minus 384k for some reason) of ram. Even with 8x1mb sticks, or 4x1mb + 4x4mb sticks... it maxes out at 5760k. Should be enough for me anyway.

If you are basing that off the post screen,the bios usually only shows the Conventional Memory and the Extended memory, so you won't see the 384k in the upper memory area.

i486_inside wrote:

If you are basing that off the post screen,the bios usually only shows the Conventional Memory and the Extended memory, so you won't see the 384k in the upper memory area.

Huh...today I learned. I never would have thought upper memory would have been missing from the post screen, but that makes sense.. I guess?

Ever heard of a board that maxed out at 6mb? I've tried re-arranging 1mb sticks, but it seems to max out at 6mb (rather than 8mb).

Hmm... that shouldn't be possible with a board slotted for eight 30 pin SIMMs. Possible combinations should be:

4 x 256k = 1MB
8 x 256k = 2MB
4 x 1MB = 4MB
4 x 1MB + 4 x 256k = 5MB
8 x 1MB = 8MB
4 x 4MB = 16MB
4 x 4MB + 4 x 256k = 17MB
4 x 4MB + 4 x 1MB = 20MB
8 x 4MB = 32MB

Apparently 16MB SIMMs existed, but I haven't witnessed these in the wild.

probnot wrote:

Huh...today I learned. I never would have thought upper memory would have been missing from the post screen, but that makes sense.. I guess?

It seems to be fairly common, I have a 286 SBC with 1MB of ram installed on it and the bios only shows 640k conventional no extended, and my CompuAdd 316s that has 4MBs of ram shows 640k + 3072K extended.

probnot wrote:

Ever heard of a board that maxed out at 6mb? I've tried re-arranging 1mb sticks, but it seems to max out at 6mb (rather than 8mb).

Seems odd to me, unless there is a weird software limit, 6mb doesn't seem to indicate a hardware limit because for 6mb you have to have 23 address lines connected and with 23 address lines it should be able to address 8MB just fine.

gdjacobs wrote:

Hmm... that shouldn't be possible with a board slotted for eight 30 pin SIMMs. Possible combinations should be: […]
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Hmm... that shouldn't be possible with a board slotted for eight 30 pin SIMMs. Possible combinations should be:

4 x 256k = 1MB
8 x 256k = 2MB
4 x 1MB = 4MB
4 x 1MB + 4 x 256k = 5MB
8 x 1MB = 8MB
4 x 4MB = 16MB
4 x 4MB + 4 x 256k = 17MB
4 x 4MB + 4 x 1MB = 20MB
8 x 4MB = 32MB

Apparently 16MB SIMMs existed, but I haven't witnessed these in the wild.

Maybe one of the last 2 sockets are bad? Oh well...It definitely allows for 4 x 1MB + 2 x 1MB = 6MB

probnot wrote:

Maybe one of the last 2 sockets are bad? Oh well...It definitely allows for 4 x 1MB + 2 x 1MB = 6MB

This is a possibility. Do you have any 256KB modules? Try adding 8 of those and see if you're getting 2MB or 1.5MB.
The 4MB sticks may be showing up as 1MB modules in case the board doesn't support 4MB modules? But I don't know if this is even a limit that actually exists and if so, in what extend this limit exists.
I do know that many boards would not support 16MB 30p SIMMs, or at least not officially.
If you have the modules, it's worth a try and it would solve this little mystery of yours 😜

Tetrium wrote:

This is a possibility. Do you have any 256KB modules? Try adding 8 of those and see if you're getting 2MB or 1.5MB. The 4MB stic […]
Show full quote

probnot wrote:

Maybe one of the last 2 sockets are bad? Oh well...It definitely allows for 4 x 1MB + 2 x 1MB = 6MB

This is a possibility. Do you have any 256KB modules? Try adding 8 of those and see if you're getting 2MB or 1.5MB.
The 4MB sticks may be showing up as 1MB modules in case the board doesn't support 4MB modules? But I don't know if this is even a limit that actually exists and if so, in what extend this limit exists.
I do know that many boards would not support 16MB 30p SIMMs, or at least not officially.
If you have the modules, it's worth a try and it would solve this little mystery of yours 😜

I have 6 x 1MB sticks in it now, but I tried some 4MB sticks from a different system and yeah, it recognized them as 1MB, but still to a maximum of 6MB. I did try adding 4 x 256KB sticks to the 4 x 1MB sticks, and now I can't remember what the result was...I think it saw all 8.

but I'm going to leave it for now. Just got the machine finished up, and I want to play with it before I tear it apart again 😀 I did a post of the finished system here: My minty 386SX-20