[Coco] Sierra Xmas 86 demo

[Theodore (Alex) Evans]

On 12-12-09 09:37 PM, Bill Pierce wrote:
>
> Stephen...
> Not sure about the 80 trk 5.25 but I think it's supposed to be dns=3 also. I think this applies to any double stepping drive and 80 trk 5.25 fits the bill so let me rephrase that
>
> SSDD - DSDD Single stepping drives should be dns=1 (35trk & 40 trk)
> DSDD Double stepping drives should be dns=3 (80trk)
>
> That should cover it better.
>
> I think it has something to do with the timing in the step rate of the double stepping drives. Gene could probably clarify this as he seems to be "Drive man" and knows more about stepping motors than most.

The reason why is so that if you put 40trk media in a 80trk drive it 
will read it properly.  While this is largely immaterial on 3.5" drives 
(I actually do own a 40trk 3.5" drive so they do exist) going with dns=3 
on 3.5" drives allows the same image and descriptor for 3.5" and 5.25" 
720k disks.

-- 
Theodore (Alex) Evans