liqmat wrote on 2020-09-26, 14:02:
Honestly would just try a different/newer MFM controller. Most problems I have run into with MFM tech is a failing cable or controller. Those full metal jacket Seagate MFM drives usually hold up pretty well in my experience. I mean, yeah, I have to tag some bad sectors, but overall they just keep on spinning. Unfortunately I am not near my gear right now otherwise I would send you a couple of newer model MFM controllers for testing.
Whoops, just realized you are in NZ. That would not be cost effective. 🤣
Well the problem is far more sinister than just a bad controller/drive or an overclocked ISA bus...
SpeedStor and SpinRite say that my ST-238R is in perfect condition, not a single bad sector (!!!) or seek error (!). [Yes, while running in turbo mode.] But any access via the DOS/BIOS disk routines provokes corruption on both read and write when in turbo mode. Even worse, it affects the floppy drive too!
This is such an interesting bug that I'm determined to get to the bottom of it! Surely must be some hardware glitch, after all. At least debugging that is a realistic option on a turbo XT clone motherboard (everything is in DIP packages on a plain old double-sided PCB with <10Mhz signals). I'd hate to have to track down a hardware fault on my 486 VLB motherboard, for instance... 😁