Bill Gunshannon bill.gunshannon at hotmail.com
Sat Nov 30 19:17:01 CST 2019

On 11/30/19 7:16 PM, Fred Cisin via cctalk wrote:
> 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 
> codes.
> 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)

I think you missed something.  This is a P112 SBC not a PC.  I watch
the head step from track to track until it runs into the stop after
passing the last real track.  I have a dbit 8" adapter and it displays
the track count and I watch it go from 0 to 79.  I am assuming the
problem is that wherever the disk parameters are being stored on the
P112 they are wrong for 8" disks.


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