I would advise a DOM, or an industrial CF. Or a very old, smaller capacity CF.

Well you have to describe what’s actually happening, which CF card you’re trying to use, its capacity, etc.

Simply put, no, it’s unlikely in the extreme for it to be categorically incompatible with CF cards. More likely it’s something to do with this particular card, or you haven’t inputted the CHS settings correctly, etc.

Does the machine lock up when it's in, or something else?

It just gives me a hard drive error, I have tried with several CHS configurations and with a real HDD drive.

Okay so if you've tried with a real hard drive and it still doesn't work then it sounds like the issue doesn't have anything to do with compact flash cards, doesn't it?

In any case we still need more details. So far all we can tell you is trivial things that you could think of yourself.

Hi. I recommend using XT-IDE Universal BIOS (on a ROM) on a network card here.
Or the floppy version, for testing purposes: XUBDisk - floppy disk XTIDE Universal BIOS booter

286 BIOSes from the 1980s have no idea about IDE HDDs yet.
They rather assume the HDD controller is an MFM/RLL controller (AT Fixed Disk Adapter) or an ESDI HDD.

The situation here is that the 286 BIOS treads the HDD controller as if it was a plain WD1003 controller from 1984.
So if the CF card does something slightly unusual, the old BIOS will be confused.

PS: It was possible to use certain pre-defined HDD types that won't exceed total drive capacity.
If you used to have a HDD that has 84 MB (say Conner CP30084E), then you could select a 40 MB HDD Type in Setup Utility and use it.
The HDD was both new enough to do logical sector addressing already, and still old enough to not use ATA-2 specification.

Edit: Simplest solution is to use an XT CF-Lite card. It's 8-Bit, though, so it slows everything down a bit.
Going SCSI route is also a possibility, of course.
Or using a DiskOnChip 2000 module on an ISA card (exotic).

Edit: @keenmaster486 I think same. Some more details could really help.
Also which type of HDD was used before, if it was a period-correct type or not (> 250MB).

Thank you so much for your support. I've now figured out what's going on. I installed a 40MB physical hard drive and selected a preset configuration, and it worked! I then tried a 16MB CF card and configured the custom CHS in the BIOS without success. It seems that configuring your own CHS doesn't work. The BIOS is a Phoenix, and you need to access it from software. Best regards.

Hi there! The 40 MB HDD likely pre-dates ATA-2 specification, that perhaps why it works on the 286.
It's a HDD from the good old days, so to say. It behaves like the BIOS expects it.

Btw, I used to have trouble with Phoenix BIOS, too.
Not because it's bad, but because it was one of the first BIOSes.
Re: GRiDCASE 1530 with patched BIOS mysteriously hangs while reading sector 1?

Edit: Hi again, you could try WHATIDE or IDEDIAG to figure out the CHS for your CF card.
Re: IDE disk-on-module + 386

The usual limits for old BIOSes are: 1024 cylinders, 16 heads, 63 sectors.
Though It's better to use a bit less. 1020 cylinders, for example. Or 15 heads (some count from 0-15).

Also helpful: How to know which hard drive limit my BIOS has?

PS: As a last resort, a socalled DDO (Dynamic Drive Overlay) can be used.
It's a little HDD BIOS that installs in boot sector, in principle.
Some work on 286 PCs, I heard.

(I misread the post)

Please try the XUBDisk as Jo22 suggested.
We don't even know whether it is a hardware problem interfacing the CF to your IDE connector, or a BIOS software issue.

dennisE wrote on 2025-05-02, 16:55:

Thank you so much for your support. I've now figured out what's going on. I installed a 40MB physical hard drive and selected a preset configuration, and it worked! I then tried a 16MB CF card and configured the custom CHS in the BIOS without success. It seems that configuring your own CHS doesn't work. The BIOS is a Phoenix, and you need to access it from software. Best regards.

I had a phoenix bios on my 386. I could not get a CF card working as a bootable drive at all. The fix was to use the xt ide bios. The same cards booted and worked on other/later machines that did not have the phoenix bios.

Which chipset does that motherboard have? Maybe there's a MR BIOS for it.

keenmaster486 wrote on 2025-05-02, 17:17:

That "16GB capacity" is all I needed to know

Um, they wrote 16MB, not GB.

Shponglefan wrote on 2025-05-02, 18:53:

Um, they wrote 16MB, not GB.

LOL I'm an idiot. Never mind. Sorry dennisE.