[Coco] floppy controller update

Phill Harvey-Smith afra at aurigae.demon.co.uk
Sun Jul 6 18:32:01 EDT 2008


Chuck Youse wrote:
> On Sun, 2008-07-06 at 16:13 -0400, Chuck Youse wrote:
> The more I think about this, the more I think it must be an interleaving
> issue.  Consider that the sectors are most likely laid out in order by
> Linux's fdformat.  Consider that I appear to be getting something in the
> neighborhood of one sector every 200-250ms, and then consider that at
> 300RPMs, one revolution takes about 200ms.  Bingo.
> 
> Does that seem right?  Is anyone even listening to my jabbering
> anymore? ;)

Yeah that seems reasonable, IIRC stock RS/Dragondos uses a 1:4 
interleave, and most other DOSes of that vintage also seemed to use 
interleaving other than 1:1, which is as you say prolly what Linux is 
laying down when formatting, which is pretty much the reason that I 
always format CoCo/Dragon disks in the actual machine and then write 
them in Linux, because interleave is set when formatting, linux will 
write it correctly, however it always formats with 1:1, dunno if there 
is a way of over-riding this tho.

Cheers.

Phill.

-- 
Phill Harvey-Smith, Programmer, Hardware hacker, and general eccentric !

"You can twist perceptions, but reality won't budge" -- Rush.



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