I’m running into an issue with HD, high density, floppies. The output on the scope looks just fine, but I get a consistent bad checksum on all the tracks. I’ve tried with and without covering the HD hole.
My floppy spec clearly says that it uses a mechanical switch to detect whether it is high density and stays in “1.0 MB” mode if a low density disk is inserted. But the floppy drive isn’t going to high density mode anyways. The output is “normal-sized”, so my groups are 4,6, and 8us wide. Just as normal.
I’ve never used a high density drive to write any of these floppies.
Amiga, with a low density drive of course, reads these floppies fine.
What the heck is going on here? The other disks I’ve tested have been all DD disks…..and they read perfect.
I’d like to get my hands on a normal original double density floppy drive……………