Hi all, I need to diagnose a faulty 8250 disk drive (actually a LP one). Years ago I found a nice program that works with a 1541 that allows turning on/off the spindle motor, seek to track 1 (i.e. bump the head to the stop), seek 1 or 1/2 track in and out. This is very handy to observe the analog signal path issues. Now I understand that this can be easily done on a 1541 since the same CPU is controlling the interface/DOS and the actual stepper/spindle outputs. Now, the 8250 obviously has two CPUs and the spindle/stepper one only executes so called "jobs" posted from the other CPU. I can see there're seek/read/write jobs but it seems to me that all will look for an actual sector header and throw back an error if that can't be found correctly. Before I dig deeply into the ASM code of the 8250's DOS, can anyone point me in the right direction to write such a tool (start, stop, step in/out) for dual CPU drives? Maybe a modified format track without switching to write mode? My other option would be writing a custom ROM for the 6530 code (that's already on a separate eprom on the LP, so nothing *too* hard to do). Thanks in advance. Frank IZ8DWFReceived on 2022-12-23 20:00:03
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