Pics or it didn't happen. 🤣

Installed my "It's ST" 486 DX4 100. Turns out the BIOS ID's it as a Cx486DX4, so ST must have licensed it from Cyrix I guess.
Hopefully I'll find time to install DOS tonight, and if so, I'll probably take a few more pictures.

Any special work/modding needed to fit the AT board into the ATX case?

Not really. I only had to remove the lower HDD cage, because my GUS is so long it would be in the way. Unfortunately the motherboard tray didn't have all the holes needed, so I've had to rely on those old fashioned white plastic support things (that you used to "slide" AT motherboards into AT cases on), to support one corner. It's sitting in there fairly well now, and I've sorted another IDE cable, so my CD-ROM is hooked up as well.

EDIT: Just wanted to mention that the HDD cage was attached using rivets, so they had to be drilled out to get the cage out. I didn't want to cause any structural damage to the case itself, just in case I want to use it for a future build.

Damn!
For some reason, I can install DOS on my CF card, but I can't boot from the CF. It simply doesn't even seem to try. Just stops after POST.
If I boot from a floppy drive, then I can access C: and find that DOS was installed successfully on it. Not sure what's wrong.
My CF adapter is a Hexin Technology HXSP-2108P. Anyone got any experience with this one? Is there another one that is known to work better?
This is getting very frustrating. Also, if I plug in my 20GB Maxtor DiamondMax8, the system doesn't even boot, although I know the HD is fine. Same thing when I plug in my CD-ROM drive.

I'm actually having a similar problem with a 512MB Viking CF card. It doesn't boot in any of my 486 systems, my Pentium 120 setup displays a letter 'j' when it should start booting DOS. The only board that knows how to boot from the card is a socket 7 ASUS SP-97XV and I'm still not sure the board is fine since it won't boot from a floppy...

Does the motherboard support LBA?

PS: Where did you get the AT I/O shield?

My motherboard does indeed support LBA. It actually detects my CF card by name, as in "SanDisk..." and so on, and I can access it just fine and partition it, and install DOS. It's just booting that is a problem.
The I/O shield I got from Evercase via Ebay.

To be fair, I expect the IDE cables I'm using at the moment may be problematic, as they are single device ones. Only one IDE plug either end. I've ordered some new ones, last 3 the store had in stock, and expect to get them in a couple of days. Hopefully, that'll sort it, if I haven't managed to sort it already.

YES!! Stupid Sandisk and their incompatible products 😜
Swapped my Sandisk Ultra card for a slower Kingston card, installed DOS and it boots 😁
Looks like I'll be spending some time getting drivers and software installed 😜

EDIT: Installed drivers for my GUS and lo and behold, it plays lovely midi music.

Congratulations 😁

Didn't think a Sandisk card would be problematic. I was gonna order two of those Sandisk Ultra III 4GB cards just because they're cheaper than the Extreme series.

Funny thing though, I tried 1Gb Kingston microSD and 1GB Sandisk microSD cards in my motorola razr v3i and only Sandisk worked!

To everyone else dealing with SD adapter problems, I managed to boot from 1Gb SD card on DX2-66 (ASUS GMIO-470 controller card, UMC chip set) only after installing Ontrack 6 Drive Overlay. It refused to work directly for some reason.

Searching through boxes of old parts, I finally found a proper 40-pin/40-wire IDE cable. This works just fine with my CF/IDE adapter, and it makes the BIOS manage to finish searching for slave device, where as the single plug IDE cables makes me have to manually skip searching for slave. Problem is, I can't get it to detect any CD-ROM drives. I've tried with a Compaq/Samsung SC-148 48X CD-ROM drive and a NEC ND-3550 DVD-RW drive.
Neither gets picked up by the BIOS. Any chance the CD-ROM interfaces on my GUS conflicting with my BIOS's ability to detect ATAPI devices? If not, does anyone have any experience with CD-ROM detection problems on SiS496/497 chipset motherboards?

LunarG wrote:

Neither gets picked up by the BIOS. Any chance the CD-ROM interfaces on my GUS conflicting with my BIOS's ability to detect ATAPI devices? If not, does anyone have any experience with CD-ROM detection problems on SiS496/497 chipset motherboards?

Most probably the BIOS does not detect ATAPI devices at all. ATAPI support was not a common feature on 486 boards.

5u3 wrote:

LunarG wrote:

Neither gets picked up by the BIOS. Any chance the CD-ROM interfaces on my GUS conflicting with my BIOS's ability to detect ATAPI devices? If not, does anyone have any experience with CD-ROM detection problems on SiS496/497 chipset motherboards?

Most probably the BIOS does not detect ATAPI devices at all. ATAPI support was not a common feature on 486 boards.

Seeing as it's a 1995/96 board, with support for LBA and such, I figured it probably had ATAPI support, but after checking the datasheets for the chipset, it turns out you are probably right.
This leaves me with either having to track down an old CD-ROM player with an interface that will hook up to my GUS (Panasonic and Sony I believe) or I need to get another controller, preferably SCSI I guess as well as a suitable CD-ROM drive.
Oh well. The fun never stops in Retroland 😁

Another issue I've run into is the turbo header. It's a three pin header, which I though normally worked as follows: Pin1+2 shorted = Low speed, Pin2+3 shorted = high speed. But with pins 2+3 shorted, Speedsys says that I've got a 15MHz CPU, an with 1+2 shorted, it reports 34MHz. Not sure if it's a fault with Speedsys, but it seems that this motherboard may have a non-standard turbo header.
Anyone got any different specs for 3-pin turbo headers?
I'm planning on trying 1+3 when I get time. Got my fiancee here at the moment, and retro computing isn't really her thing.

LunarG wrote:

5u3 wrote:

LunarG wrote:

Neither gets picked up by the BIOS. Any chance the CD-ROM interfaces on my GUS conflicting with my BIOS's ability to detect ATAPI devices? If not, does anyone have any experience with CD-ROM detection problems on SiS496/497 chipset motherboards?

Most probably the BIOS does not detect ATAPI devices at all. ATAPI support was not a common feature on 486 boards.

Seeing as it's a 1995/96 board, with support for LBA and such, I figured it probably had ATAPI support, but after checking the datasheets for the chipset, it turns out you are probably right.
This leaves me with either having to track down an old CD-ROM player with an interface that will hook up to my GUS (Panasonic and Sony I believe) or I need to get another controller, preferably SCSI I guess as well as a suitable CD-ROM drive.

Well, you don't really need BIOS ATAPI support to use an IDE CD-ROM. You just cannot boot from the CD-ROM.

Problem isn't that I wanna boot from it. I want it to simply detect the CD-ROM. It doesn't even sense that it's there. I've tried with 4 different units now and none of them are detected by the controller.

If you just want to use a CD-ROM, it is irrelevant whether the BIOS knows about it or not. At which stage are your CD-ROM drives not detected?

Have you tried loading MSCDEX just for the heck of it?

5u3 wrote:

If you just want to use a CD-ROM, it is irrelevant whether the BIOS knows about it or not. At which stage are your CD-ROM drives not detected?

If the BIOS, or rather, the IDE controller, doesn't detect that there is a device connected, how would DOS be able to access the device. It's just like when the BIOS doesn't detect the CF-IDE adapter, the system can't boot from it and DOS doesn't see that it's there.

I may do as Half-Saint says though, and load MSCDEX anyway, just to rule out any eventualities.