[Coco] Multiple HDB-DOS 256 drive partitions Software Wanted

[Bill Gunshannon]

> Oh, bummer!   I was hoping for a PC style partition table, or any style
> partition table that would support more than two operating systems.  I was
> also hoping too hard that this data would be stored on the disk itself
> rather than in ROM ( like a volume carrying its own metadata ).   Sorry,
> it
> seems my "what if" and "geeze whiz... that would be cool"  must have
> mis-translated this thread!   :)

I don't see any reason why that can't be done.  As long as all the OSes
you expect to be run on the COCO know about and abide by it.

You take the very first sector track or whatever and you write your
partition table there.  And every OS has to know that the first step
in initialization has to be reading this information and acting
accordingly.

Someone care to tell me why this couldn't be done?

bill

>
>
> On Thu, Apr 25, 2013 at 5:09 PM, Robert Gault <robert.gault at att.net>
> wrote:
>
>>
>>
>> The partitions referred to in this thread should not be confused with PC
>> hard drive partitions. HDBDOS and RGBDOS split a hard drive into two
>> sections based on three bytes in the Disk ROM. These bytes, $D938-$D93A,
>> give the address of the first Disk Basic sector on the hard drive. There
>> is
>> no indication on the drive itself that sectors differ on either side of
>> this "border".
>>
>> The sectors can be any size in bytes and that is a function of the hard
>> drive, hardware or emulation. Regardless of the sector sizes, Disk Basic
>> can only use 256 bytes per sector. The rest will be wasted unless unless
>> the ROM is modified to work with pseudo sectors. OS-9 can do this but
>> there
>> is not enough room in the Disk ROM to compensate for alternate size
>> sectors. Only the first 256 bytes will be used.
>>
>> All emulators use 256-byte sectors.
>>
>>
>>
>> --
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>> Coco at maltedmedia.com
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>>
>
>
>
> --
> Brett M. Gordon,
> beretta42 at gmail.com
>
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> Coco mailing list
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> http://five.pairlist.net/mailman/listinfo/coco
>


-- 
Bill Gunshannon          |  de-moc-ra-cy (di mok' ra see) n.  Three wolves
billg999 at cs.scranton.edu |  and a sheep voting on what's for dinner.
University of Scranton   |
Scranton, Pennsylvania   |         #include <std.disclaimer.h>