[N8VEM: 16587] Timeouts at Zeta compatible floppy controller

[Oliver Urbann]

Hi all,

I have built a Z80 SBC with a floppy controller compatible with the one of the Zeta SBC (with an FDC9266). I use the floppy code form RomWBW and some parts work. For example Sense Interrupt and Specify result in the return code 0 (ok). But A read command afterwards results in an timeout. All 9 command bytes are sent and look correct but in the execution phase I only receive 0x70 (i.e. CB = 1, EXM = 1, DIO = 1 but RQM is 0). So it is in execution mode, reads something but does not have any byte to read. This state never ends. I also can see with a LED attached to the raw read pin of the FDD that there is something that is sent by the floppy, also the floppy LED lights up. Does someone know how this can happen? Thx!

[Wayne Warthen]

These symptoms are what you would see if there is no disk in the drive or
the drive is not spinning... Does motor on/motor off work?

--Wayne

Post by Oliver Urbann
Hi all,
I have built a Z80 SBC with a floppy controller compatible with the one of
the Zeta SBC (with an FDC9266). I use the floppy code form RomWBW and some
parts work. For example Sense Interrupt and Specify result in the return
code 0 (ok). But A read command afterwards results in an timeout. All 9
command bytes are sent and look correct but in the execution phase I only
receive 0x70 (i.e. CB = 1, EXM = 1, DIO = 1 but RQM is 0). So it is in
execution mode, reads something but does not have any byte to read. This
state never ends. I also can see with a LED attached to the raw read pin of
the FDD that there is something that is sent by the floppy, also the floppy
LED lights up. Does someone know how this can happen? Thx!