Fred Cisin cisin at xenosoft.com
Sat Nov 30 18:16:01 CST 2019

On Sat, 30 Nov 2019, Bill Gunshannon via cctalk wrote:
> I'll start with the simple and funny one.  If i run FORMAT
> it formats all 80 tracks.  :-)  Seems like the definition
> for an 8" disk as selected in the config menu is just plain
> wrong.  Of course, once it formats all 80 :-) tracks any
> attempt to access it, like a DIR, just returns "sector not
> found".

A lot could depend on how the software is interpreting the FDC return 

In the case of PC BIOS (765), error code number 4) that would mean that it 
did format; it sees sectors, but not the one that you asked for.
That may be that the format command setup and the read are in 
disagreement on sector numbers, and/or sector size.

It could also happen if it ended up on the wrong track.  (then the C field 
of the CHRN of the sector doesn't match the C field of the CHRN requested)
Even a non-functional stepper could do that.  Be well aware thet "VERIFY" 
checks whether there are READABLE sectors, not whether they have correct 
content.  If you want RELIABLE code, include a READ after WRITE, rather 
than rely on the FDC "VERIFY".
A non-functional WRITE (including FORMAT) will VERIFY just fine, but leave 
behind whatever had been on the track before, rather than what you though 
that you had put there.

PC FDC returns error code 2 for not seeing address mark.  However, MS-DOS 
goes through a short list of codes that it knows, and then falls through 
to "error, but none of the above" and says "General Failure" (I can't help 
but think that that was one of the brass in VietNam)

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