[Coco] Cobbler and hard disks was:Re: shell in NitrOS-9

[Gene Heskett]

On Thursday 21 January 2010, Bob Devries wrote:
>Apart from the Burke&Burke XTROM system, I don't know of any Coco hard disk
>system which will boot directly to OS9 from a cold start without a floppy
>disk.
>
>I've been hoping to see such a system for my SCSI setup, but it never
>happened.
>
>Regards, Bob Devries
>
HDB-DOS can.  By default, if you take no keyboard action during the 
countdown, it will boot from the hard drive IF the hard drive has a sort of a 
partition on it that is hard coded into HDB-DOS, by treating that location on 
the drive as a std n35 track SS floppy.  Access to this floppy image is, if 
you do not have the superdriver stuff, by first building a boot disk that 
will boot as a floppy but winds up using the hard drive after loading the 
bootfile, and then changing the build script to make it use the hard drive 
boot module and rebuilding that disk.  Then its backed up by doing a drive 
off in HDB-DOS basic, then a backup 0 to 128 from HDB-DOS basic.

If you have the surperdriver kit, the newer versions of it include 
descriptors which allow nitros9 to access these floppy images once they have 
been preset to the correct values in the wpc and ofs variables.  In my case, 
using a 1Gb drive, with the first half formatted for os9, the last sector os9 
uses in $1DBB8F, so I have about 500 megs available for nitros9's use.

As that is only half of this drive, then the descriptor is permanently set by 
using dmode's -file feature to set wpc=1D, and ofs=BB90, and a new boot built 
with that descriptor in it.  Then next sector then can be the start of HDB-
DOS basic's drive 0 when the drives are on.

In this special case, since a hard drive has no use for the stp variable in 
the descriptor, that is set to a hex value that corresponds to the virtual 
floppy that may or may not exist in that space above the nitros9 'partition.
My sh_tc3.dd is normally set to $80 in the stp byte, with $80=drive 128 to 
HDB-DOS.

The superdriver driver then takes the stp value, multiplies that by the size 
of a 35TSS floppy, then adds the offset, and uses that to address that 
particular virtual floppy on the hard drive.  With a 1Gb drive, I still have 
a bit more than 400 megs of unused drive left, even after formatting 255 
floppy's out of the second 500 megs.

If all this sounds like a commercial to sell both of Marks drive controllers 
(I believe the GCCC ide also works), HDB-DOS, and the superdriver package, it 
is.  It Just Works(TM) once you understand it.
[...]
>>> Related, but not, can I cobbler a HD and make it a boot disk? I want to
>>> try it, but I'm afreaid if it doesn't work, I'll have to reformat the
>>> drive, and I just did that. I don't want to have to reformat the very
>>> next day, so I'm asking first. lol

Don't cobbler, that will write the wrong boot module, but os9gen from the 
later nitros releases can do this I believe.  In fact, I am going to go test 
that theory right now, brb.

Short answer, no, os9gen fails, claiming a disk id change.  Format also 
failed and had to be run by hand because when working with a hard drive it 
requires about 4 more presses of the y key to proceed.  Then it proceeds to 
write defective data from $10 on in lsn0, leaving that mostly empty.

So, os9gen fails too, but not until it has created a $3000 byte long, empty 
'tempboot', and no track 34 is written either.  But the copy operations later 
in the script that do a couple of makdirs, put a merged shell and grfdrv in 
cmds, and errmsg in sys, those all work.  I need to figure out where the end 
of that floppy image is, and setup an /s1 descriptor that points at the 
remainder of the disk, another partition, and play with that. No luck there 
either, as much because if I fire off format, I want to know the figures I 
have dmoded into /s1 are correct.  Else _I_ start from scratch. :(

>> cobbler writes out the bootfile in memory to a device.  If your bootfile
>> boots from a floppy disk, then cobbler'ing to a hard drive really doesn't
>> buy you anything.  Plus cobbler writes to track 34 (sectors 618-630)
>> which would require special a special ROM.  For those reasons, I don't
>> think cobbler will work.
>>
>>> Wayne
>>>
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>>
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-- 
Cheers, Gene
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