(this is being posted to several places, so some context is given)

Am currently debugging a replacement for a hard drive setup in a GRiDCASE 1530. (an 80386 laptop, running MS-DOS).

It uses a Phoenix BIOS dated 10/25/89, and does not have a ROM setup program, but rather automatically configures itself on each power-on.

The BIOS has been patched to always present a hard disk geometry of 992 cyl, 16 heads, 63 sectors (for 512 megabyte cards), and this geometry has been verified with IDEID with each of the cards I am using. INT 13H is set up to utilize this geometry.

Am testing a couple of different adaptors:

Startech IDE2CF
Startech IDE2SD

All with a smattering of both CF and SD cards sized 512 megs, all verified with the geometry stated above.

I can usually get to the point where I can with GRiD MS-DOS 3.30, FDISK, to create a 32 megabyte initial partition, FORMAT C: /S/V, and be able to copy files onto the resulting volume.

But when I boot the result, the BIOS hangs trying to access the first sector.

When attempting MS-DOS 6.22's setup procedure, it creates the partition, but hangs, again, first sector, when trying to format the disk.

What could be causing this mysterious behavior? It seems to exist across various different adapters and cards.