[Coco] Re: NitrOS9 on MESS?

[Gene Heskett]

On Friday 05 December 2003 00:03, Roger Taylor wrote:
>At 08:44 PM 12/4/2003 -0500, you wrote:
>> >> cc3disk.  The fact that the bug occurs when used with a VHD -
>> >> thus bypassing cc3disk - confirms this observation.
>
>Unless there is a duplicate set of problem code in either module for
> disks and vhds.
>
>> >> bug, but what kind of timing bug would cause this bug.  As for
>> >> "index hole signal code", can you elaborate on what that is?
>
>I've always read that M.E.S.S. emulates the hardware as much as
>possible.  Perhaps it emulates the pulses generated by the passing
> of the index hole of a real floppy disk when a .dsk is mounted and
> accessed.  Anyway, I think someone reminded me that it is only used
> when formatting a floppy disk on a real CoCo controller. 
> Personally, I never had a need to know much about the index hole of
> a disk.
>
>>I only know of one drive and driver that ignores the index pulse,
>> and thats all 68k based amigas ever built, because they do read,
>> and write, a whole track at a time with no regard to the index
>> pulse.
>
>Then how did it prevent from writing a track over the hole itself? 
> :)

The index hole is close to the center hole of the disk, and the heads 
never reach that far inward so its a non-issue.  This hole has no 
bearing on the snips and such in the edges of the sleeves, or the 
slider covers in a 3.5" diskette.

>
>>   It
>>reads the whole track and a bit more into a buffer, and searches
>> the buffer for the right "sector" address.

-- 
Cheers, Gene
AMD K6-III at 500mhz 320M
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Copyright 2003 by Maurice Eugene Heskett, all rights reserved.