What are the specs of the 486? Later ones should handle 4gig drives fine. If it an earlier system try EZDrive. EZ-Drive Dynamic Drive Overlay
Other options are a XT-IDE card or a nic fitted with an eprom chip with XT-IDE bios fitted to the boot rom socket. Link to EZ-Drive with Fat32 support. https://drive.google.com/file/d/0B45ujxJF8aN- … TBjNFUyU1k/view

MBR damaged for example.

During installation, it should ask to create a rescue disk for such a situation. You can also re-install it, but afaik this will wipe all data.

Both OnTrack and EZ-Drive were giving me inconsistent drive information with the three CF cards I tested and BIOS was also acting strange when detecting two of them so I'm guessing the adaptor is dodgy.

That still doesn't explain what happened with the hard drive that was in it and working perfectly until last night.

In the guide for EZ-Drive where it mentions this,

"Format partitions and install MS-DOS

Restart and boot from C:

It is crucial that you always boot from C: so that EZ-BIOS is getting loaded! If you want to boot from A: then boot from C: but hold down the CTRL key. A boot menu will appear allowing you to continue booting from A:"

Is that just letting it boot the hard drive without interference by inserting disks or is it a BIOS option to change the boot order to boot C first?

Confused now because I put a new 160GB Seagate drive in and installed EZ-Drive on it and like Phil said it gives you an error for creating too many partitions. For me it cut the drive down to 8GB and split it into four 2GB partitions then after all that it restarted and stopped just after it tells me how much cache is installed and the CPU speed.

What should happen is the overlay loads and lets me continue installing DOS, but instead it appears to be doing exactly what OnTrack started to do last night, stopping at the point it's meant to load.

Is there boot sector virus protection setting in BIOS setup? Try disabling it if it's enabled.

Sticking a bootdisk in and booting straight from A: will bypass the DDO. DDO jgives you the boot from A: after the DDO have loaded allowing you to access the drive.

Usually if you boot from A: with a boot disk and fdisk/mbr you replace the DDo in the master boot record and go though the whole process of setting up the disk again.

On a 160gig partintion formatting at fat16 2gig partitions will give you issues. Try a smaller drive or format as fat32 and use MSDos 7.1 or Win9x on the system.