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RE: [N8VEM-S100:4555] Re: Get the ZFDC controller to format a disk...

I don't know anything about the ZFDC controller, but I've been pondering this problem.  It's weird that it can read and write to the disk but not format.
Format is just another kind of write.  From what I've learned about the FD1771 chip, format is a Track Write, while regular read/writes are sector based.
For regular read/writes, the controller reads the sector from the disk as it's spinning, then for reads, it proceeds to read the DATA sector following a matched ID sector, for writes, it quickly switches the head to perform the write to the data sector and writes the preamble, data, crc and postamble.
Now, for Track Writes, it waits for the INDEX hole and writes a track preamble, then ID & DATA (0xE5's) for all 26 sectors, don't think there's a postamble?
Perhaps your INDEX isn't working?  That's a photo eye, and not uncommon for the LED to burn out.
But, the standard IT Crowd question must be asked.  Have you tried turning it off and on again?
Good luck


Date: Mon, 14 Jul 2014 09:33:12 -0700
From: f.schi...@googlemail.com
To: n8vem...@googlegroups.com
Subject: [N8VEM-S100:4555] Re: Get the ZFDC controller to format a disk...

John, if i use the R/W tests on a formatted floppy, the WP functions works as it should be.
With an 8" disk with open notch i get a message from ZFDCDIAG regarding the write protect.
The 8 bit decoding isn't the reason.
After hours i try again to format the disk in the same configuration, again the WP and HALT LED are on and nothing happens.


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