Basically there should be at least one screw that holds the motherboard in its case.
But I guess you're right, that particular case is not matched to that motherboard.

Well, there are actually even 2 (plastic mounts) that fit (marked with green arrows in my sketch). But the other two do not fit, so if I leave in the plastic separators the board "wobbles" around, but if I remove them, the backside of the board lays on bare metal of the second (middle) mounting rail (which could and probably would short some circuits).

BTW - the computer is called "Cardinal VGA100" and I have found nothing about it. There seems to be a VGA card by that name, but not an AT computer ?! Im puzzled.

best

I can't tell for certain but the positions where the standoffs are supposed to slide in place look like they're meant for an XT board layout rather than AT.

Did a quick google search. Cardinal Systems still seem to have a website going. It hasn't been updated in a while from the looks of it but you might try and send them a mail, see if they still know the PC model that used to go into this case.
http://www.redcardinal.com/

As mentioned above, the standoff positions in that case are intended for XT style motherboards (notice the PSU is also XT form factor), so it may have been originally an XT clone. My XT clone case is almost identical to the one in your photos.

Mounting hole locations on Baby AT motherboards can vary quite a bit. Usually they always have holes for the standoff positions that are common for both AT and XT boards, but they can also have AT-specific mounting holes (like the two that don't match up in your case) or XT-specific mounting holes, or a combination of both. As you can probably tell, the Baby AT "standard" was not really strict.

You can still use that motherboard in that case, although you need to get creative and maybe add some padding under the standoffs that don't line up so you have support for that section of the board.

AFAIK, "generic AT" = what you find in turn of the millennium combo AT/ATX cases = Baby AT ≈ IBM XT/286 (5162) or the later "tower" variant with the mains in/out cable for a front mounted switch, while a true AT (5170) or mechanically-compatible is rather different and a relative failure in the open market!

Thanks a lot for the clearification. I have an additional question: I have little experience with AT systems, but NO experience with XT, systems. However, If I were to get me an XT motherboard, I would also need ALL additional peripherals (except the PSU), e.g. floppy controller, vga card, floppy drives that came with this (386DX) system would all not work ? Is that correct? Thanks.

If your cards can run in 8-bit ISA mode it should work just fine with your old stuff.
Most of my 16 Bit ISA graphics cards work in a 8 Bit slot for example.
With a XT-IDE you can also go for solid state storage instead of a HDD for example. https://www.xtideuniversalbios.org/wiki

DerBaum wrote on 2023-10-31, 23:14:

If your cards can run in 8-bit ISA mode it should work just fine with your old stuff.
Most of my 16 Bit ISA graphics cards work in a 8 Bit slot for example.
With a XT-IDE you can also go for solid state storage instead of a HDD for example. https://www.xtideuniversalbios.org/wiki

Some VGA cards, like Trident based cards, will have an 8-bit/16-bit jumper on them. So look out for that.

kingcake wrote on 2023-11-01, 00:40:

Some VGA cards, like Trident based cards, will have an 8-bit/16-bit jumper on them. So look out for that.

Yes.
Re: Resurrecting a Lanner AP-40AHD board PC
I dont know why but it even worked jumpeder for 16 bit in a 8 bit slot.

Aui wrote on 2023-10-31, 22:56:

Thanks a lot for the clearification. I have an additional question: I have little experience with AT systems, but NO experience with XT, systems. However, If I were to get me an XT motherboard, I would also need ALL additional peripherals (except the PSU), e.g. floppy controller, vga card, floppy drives that came with this (386DX) system would all not work ? Is that correct? Thanks.

As others have said, some older VGA cards can work in 8-bit slots so it depends, if you tell us what graphics card you have we may be able to tell.

I/O controllers for XT systems are slightly different from the 16-bit ones as they usually include a real-time clock (since XT motherboards do not have one) and the floppy controller only supports double density drives.

For storage an XT-IDE card is the best option, unless you want to go full retro with MFM/RLL controller and drives.

But XT clones are pretty slow and not the only option, so maybe you want something more useful that also allows you to reuse the 16-bit cards you already have. In that case you can look for older 286 Baby AT motherboards that have the XT-style mounting hole positions and will fit perfectly in your case. One example that comes to mind is the PCChips M205 but there are other examples you can find online. The reason for this is that some of these XT style cases were also sold with budget 286 boards back in the late 80s/early 90s, so an older 286 is also a great fit for your case and may be more flexible and cost effective than trying to source XT hardware.

Thanks again for the support. For now I have solved the first half of the puzzle. I found an appropriate case for the motherboard and now I have a great 386 with 2 working floppy drives and 1 MB RAM. Now I need to find some hardware for the other case - if find something suitable, I will update this post. Next, I will try to get Wing Commander running on this machine.

Cheers!

I am wondering if Wing Commander with only 1MB of Ram is a lot of fun?
Meanwhile I got something else that I wanted to ckeck for a long time...

Hi again,

For some reason I thought the PC has only 1 MB of Ram - but that was not correct. Its got actually 4 x 1MB - however, something is still not right. When counting up during the Ram-test I only get 3712 KB. Thus I end up with 3072 MB extended memory and 640 conventional. Any ideas what I am missing here ?

I tried to Boot the PC with only 2 SIMMs (variably exchanging them) - but in that case the PC is not booting at all ? So here are my questions:
- Is one of the RAM sticks bad ?
- If I replace tem - do I need again 4 identical ones ?
- and would "non parity" SIMMS work as well?

thanks for the help

It's OK, the 4MB are being detected correctly. What happens is that the first MB of memory is divided as: 640KB (Conventional Memory) and 384KB (Upper Memory Area). The remaining 3072KB are used as extended memory.

The Upper Memory Area (UMA) is used for things like mapping video memory and shadowing ROMs that contain the system/video/SCSI BIOS and similar. Normally programs cannot use the UMA, but with memory managers such as EMM386 you can reclaim unused blocks from the UMA in the form of Upper Memory Blocks (UMBs).

The board will not boot with less than 4 SIMMs since the 386DX has a 32-bit memory bus, and each 30-pin SIMM is 8-bit, so for one 32-bit bank you need 4 SIMMs.

Mmm - I seem to struggle with very basic things - you are right mem sees 4MB, yet it seems part of it is somewhere reserved. So I cant get memmaker to free it up neither as extra EMS nor XMS. Doom wont run. Is it possible that the graphic card is using system RAM ?

Forgot one image from the Realtek vGA card - it says something like 1024K DRAM.... VGA mode ?

Shareware Doom runs fine on 4mb, it appears you are booting with smartdrv or some other massive memory wasting hog.

Why not make a boot disk to boot cleanly without any utilities or memory management?

Dos 6.22 you could hit f5 to bypass autoexec and config.sys, that should do it.

Aui wrote on 2024-01-24, 05:20:

Forgot one image from the Realtek vGA card - it says something like 1024K DRAM.... VGA mode ?

Just a low end SVGA card, 1mb was excellent for windows and slow paced dos games and utilities but generally doesn’t do much for doom, having a fast dos compatible video chipset would do more, especially if you can overclock your ISA bus without crashing.

Ahh thanks, now I got it right (too long ago when I could do it myself)