Hello

I have come across an interesting problem that I'm unable to solve. I have an ASUS PCI/I-P54SP4 motherboard with a Pentium 90 CPU and 32MB EDO (72 pin) RAM.
The M/B used to have BIOS rev 104, but even with the latest rev 109, the problem persists.

I set the floppy (A:) drive type to 3.5in/1.44MB in the BIOS (Drive B: is None). I reset the PC. Everything looks fine during POST, the drive seeks okay.

If there is a bootable disk in drive A:, the PC boots from it and things just work.

However if I boot from the hard drive (I've tried multiple hard drives in multiple modes (normal, large or lba)) the same MSDOS version 6.22 as is on the disk, the drive A: won't read any disks and will
error out with 'sector not found'. I have no autoexec.bat or config.sys on the hard drive so no device drivers are loaded.
After 2 days of enabling/disabling various options in the BIOS, I've discovered that if I boot from HDD, running MSD shows drive A: to be 5.25in/360K type which would explain the sector not found error.
But if I boot from the disk (the same disk for which I got the error just a reboot ago), the drive type is correctly set to 3.5in/1.44MB.

The floppy/hard drive controller is integrated on the motherboard. I am unsure if it is an SMC chip or a CMD640b chip. The M/B has a secondary ide controller which could be the CMD640b, nothing is plugged into it.

Would anyone have any ideas what to try or where the problem is?

Thanks,
Rob