HP 9816 CP/M-68K

Fred Cisin cisin at xenosoft.com
Mon Feb 12 15:14:56 CST 2018

>> But, I don't know how to FORMAT a track with multiple sector sizes with
>> NEC 765 type controller.  Not as hard with WD style controllers.

On Mon, 12 Feb 2018, Eric Smith wrote:
> Format a track with the sector size that occurs later on the track, with
> dummy sectors ahead of them and gap sizes selected to position them
> properly.
> Start formatting with the sector size for the earlier sectors. Abort the
> format at the time when the desired number of sectors have been written.
> I'm not sure whether there's any way to abort a track format on a PC. I did
> it on a machine that had control over the μPD765 reset pin.

Thank you!

> Definitely much easier with the WD style controllers.
> It is possible to format disks on an NEC style controller with a format
> that cannot be created on a WD style controller, for instance using
> particular track or sector numbers above 0xf0, which are specially
> interpreted by the WD during a track write.

I still feel that "multiple sector read/write" on NEC765 is less useful 
than "track read/write" of WD 179x.
In spite of WD's handling of what it interprets as address marks, etc.
'Course OUR needs are not always the same as the general public's, . . .

Is there any truth to the rumors that the choices of Data Address Marks 
(DAM-it!) on TRS80 was due to a misprinted or misread data sheet?
And that Tandy wasn't a big enough player for WD to consider a variant of 
the 179X that could support those DAMs?
We were not amused that the Model 3 could not write a true model 1 disk, 
and that Doubler, etc. had to contain BOTH 177x and 179x chips!

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