[Coco] Re: [Color Computer] Create NitrOS9 L1 boot disk for Dragon with FD-502?
afra at aurigae.demon.co.uk
Sun Sep 24 13:18:32 EDT 2006
Gene Heskett wrote:
> On Sunday 24 September 2006 05:45, drag0n1969 wrote:
>> Creating a NitrOS9 boot disk is a problem, since the Dragon Dos
>> expects the boot sector on track 0 (from sector 3), and not track 34
>> as on the CoCo (though both of them load the boot sector to same
>> memory address at $2600)
>>From sector 3? Since the F.A.T. starts at LSN1 on a coco/os9 disk, and can
> extend to 65535 bytes, which is several tracks, dragon either moved the
> F.A.T., or did some other VERY interesting tricks. Please tell us more.
Yep sector 3 :) this is really only a problem for DS80 disks, as they
have more sectors than can be mapped in a single sector blockmap. Since
Dragon Data OS-9 only supported single sided disks this was not a
problem. When I was setting up the Nitros port, I decided that the
easiest way was to up the sectors/cluster so it fitted...it seems to work :)
> And it would also need to be patched for the number of sectors to load
> unless the dragon boot track is shorter. As every byte of track 34 is in
> use for the coco, I can't imagine how the dragon could get by with an
> initial load thats 768 bytes shorter. It simply wouldn't fit.
Yeah the Dragon boot track is 16 sectors, so 0.5K shorter than on the
Tandy. It will fit though it is a squeeze on the Alpha due to the extra
overhead in the disk module.
Phill Harvey-Smith, Programmer, Hardware hacker, and general eccentric !
"You can twist perceptions, but reality won't budge" -- Rush.
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