Maeslin wrote:

One option might be to try one of the drive overlay softwares, then try installing DOS again?

Hm, I'm not sure which DDO would be appropriate for a DOM.

stamasd wrote:

I personally didn't attach the DOMs to any computer apart from the one listed above. When I received them they did have some "non-DOS" partitions as seen by the DOS fdisk which were listed at 4GB and 8GB respectively, which I deleted. It was funny how fdisk reported on the same screen that the drives had 4 and 8GB partitions respectively, all the while telling me that the disk size is 504MB.

It's just a wild guess, but I think that could be part of the problem.
Some spurious data could still be left in track 0. FDISK isn't very accurate when modifying the MBR..

See this link about the famous "fdisk /mbr" command. It says:

"People often recommend the undocumented DOS command FDISK /MBR to solve problems with the MBR.
This command however does not rewrite the entire MBR - it just rewrites the boot code,
the first 446 bytes of the MBR, but leaves the 64-byte partition information alone.
Thus, it won't help when the partition table has problems."

I should probably note that I read somewhere that the FDISKs from DOS 6 and 7.x/8 are said to behave differently here.

Anyway, it shouldn't hurt to wipe the DOM with another type of application, just to make sure. 😉

The MBR can be erased nicely on Linux, as described here.
XFDISK and Super FDISK can also come in handy to create DOS partitions.