You can always downgrade to 6.3. Or try to convince pcdosretro to come back to the forum and hope he still has the source
I no longer remember where to find the original source, but here's an old website that cites it.
The author of PC-DOS 7 was also a member here at one point under the handle pcdosretro, and he himself corroborated it
Any way to patch PCDOS to address this issue? I have GLaTICK running on my Compaq Portable with an AST MegaPlus II (running PCDOS 2000 with a V20) and was scratching my head on why it didn't quite work!