I find Free FDISK from FreeDOS works better than the regular MS-DOS FDISK for this type of thing.

The partition was active already - took me a while to find out as to make it active it needs to be drive zero but the system would map as drive zero the boot drive and that did not boot. I could check only when I used a floppy to boot.
I don't remember being asked about marking the partition as active to be honest. I repeated the process several times! 😀

Not sure I'm familiar with the overlay software to be honest. Can you link me to the right direction? To be fair I'm not expecting a 4GB CF to work with a 286, I might source a smaller one and I am looking for a reasonably priced - and supported - network card for XT-IDE as well.

It will work for 286. Personallly I use either ezdrive or ontrack disk manager. You Can find both on phil's computer lab websites.
However, it will overwrite everything on your CF card and floppy boot in order to install DOS will be only possible if certain hotkeys are pressed when booting from cf.
Keep in mind that in order to work machine can only be booted from cf as overlay software replaces some of bios functions. Booting from FDD is possible only the way I described above.
The software actually overwrites MBR, which allows overlaying BIOS functions so bigger disks can be recognized properly.
To make it work properly on machines which BIOSes does not support LBA (typically 286, 386 and some 486), just input max CHS values on hard disk C in BIOS.
This is the way I made my 286 work with CF cards (and HDDs) bigger that 512MB.

Well that sounds like good tip.

I'll look into that, thanks for the idea!

tony359 wrote on 2022-10-03, 21:53:

Can I ask why that is a necessary step?

Thanks again!

The MBR is in the first sector of your HDD and it identifies where the OS is located. This allows your PC to know where to look for the OS and get it into the memory.

I ended up buying an ISA network card - I waited until I could find a cheap one. I need to burn the XT-IDE eeprom.

For now the CF adaptor works like a charm but I am working on some socket 7 mainboards.

Not always, fdisk should ask if you wish to make first partition active.

The thing is that it was active, I managed to check. But it would still not boot.

You could use one of these tools-- They are probably the easiest solution.

http://www.vogonsdrivers.com/index.php?catid=19

EZ-Drive version 9.09W is probably my favorite since it uses standard partition types.

It puts a custom MBR on your storage device that patches your BIOS on bootup. It also has fast partitioning and formatting tools.

Just don't use FAT32 partitions or try to create any partitions > 2GB on DOS 5.