Request the appropriate vendor pages from the SCSI device to query whether it actually is expected to support the features.
Possibly support different feature levels/revisions of the interface.
Split into more files, and reconsider project structure.
Try to make it work with Adaptec EZ-SCSI v5 drivers.
Test with LSI (I-O DATA) driver.
Test under Windows 9x DOS box.
Possibly implement workarounds.
Investigate how much code can be shared between OS versions.
Build a user interface, probably based on dialog templates, for Windows 3.x.
Implement ASPI calls.
Investigate shell extension UI for Windows 9x.
Investigate CLI version port for NT.
Convert filenames to supported format.
Prompt before overwrites.
Upload support.
Firmwares with bugfixes have been released.
Use a handwritten makefile instead of the OpenWatcom IDE generated one.
Build on modern Windows and transfer exe to test machine.