I'm getting very strange errors now. Programs copied to the hard drive can't be executed. For example: I have the BIOS files and idecfg.com on a floppy disk in the A: drive. I invoke idecfg.com from the A: prompt, works fine. I change to the C: drive, make a directory called XTIDE, change to that directory and do a copy A:*.*. The copy does not report any errors and a DIR of the XTIDE directory looks good with correct file sizes and such. I invoke idecfg.com from within the XTIDE directory and the system hangs. In one case, which I have not been able to duplicate, when I invoked idecfg.com, the boot menu appeared, it counted down but then reported "Non-system disk... Replace and try again". Rebooting got the same result. I then installed the drive in another machine and saw that all the data on the drive was wiped.
I formatted the drive and installed DOS and some utilities on the drive in another machine. The programs copied to the drive while in the other machine work fine, only programs copied to the drive while it is attached to the XT-IDE card exihibit problems.
This happens with both RC1 and RC2 of aitotat's BIOS.