I have just got my ZFDC board working
today after waiting 3 weeks for a WD2793 to arrive from
China (my first WD2793 from another US supplier was dead).
I'm using ZFDCDIAG.COM to test the
board, all my boards are S100Computers.com boards, Z80CPU,
RAM/ROM, Console, CF IDE board on default ports.
On ZFDC firmware V2.8 everything seems
to work fine, I can format a 3.5" floppy for CPM or DOS, I
can perform random read/write tests all OK.
On upgrading to firmware V3.5 I noticed
that the format disk command '00' seems to send the ZFDC
board into reset with the two left hand digits clocking
over (like before the board is initialised), disk random
read/write seems to be fine and read sector etc, it only
plays up if I try to format a disk
Reverting my firmware back to V2.8 and
Format works fine.
Can you check on your board with a 3.5"
disk to see if any bugs have crept in to the latest
firmware version.