[Coco] Hacking the SuperIDE

[Gene Heskett]

On Wednesday 03 October 2012 13:30:51 Retro Canada did opine:

> on my side I could not make the /ih descriptor to work.
> 
> There is something broken here. First it mounts itself as I0 and the
> offset is zero, as well as stp and

Well, I don't have the SuperIDE although it is under consideration.  Bear 
in mind also that HDBDOS itself, unless you run a program that patches 
those 3 bytes in the same manner as I describe for nitros9, it would be 
limited to the one its set for.

But I've no clue if there is an /sh equ descriptor for the HDBDOS and 
SuperIDE setup.  Since this is essentially external to the disk, I see no 
real reason why it could not be done if it hasn't been.  Or is that what 
your /ih is, which makes sense.  Note that if it didn't work for anything 
but a "dump /ih@", that would be normal I believe until /ih has been 
formatted.  But before I did that, I would make sure the wpc and ofs were 
set correctly FOR YOUR hard drive.  Get the total sectors from a free /ih, 
get its partition size

free /ih (example)
Capacity: 1,948,560
make that number you get into hexidecimal
0x1DBB90 (example, use your figures)
and do "dmode /ih stp=80 wpc=1d ofs=-bb90
And /ih should now be pointed at the LSN0 of vdisk 128.

I would first backup the image you have just in case, and then attempt to 
format /ih from nitros9 if you are going to use it for nitros9 stuff.  If 
it doesn't say its a 630 sector single sided disk, hit n when it asks. No 
writes will be done & format exits.

Note also that I have had the superdriver kit since forever, and it 
'deblocks' the disk, storing the odd sector in the high half of a 512 byte 
disk sector, so essentially I see the disk on a byte for byte basis, not on 
a coco sector being in the first half of a 512 byte disk sector, and 
therefore wasting half the disk.  With disk space these days being a shrug, 
that point is moot, but SuperDriver has other advantages.  But I did find a 
wart a day or so back, has to do with the dns byte, something I'll have to 
sort out eventually.  It tried to format /dd when I told it /s1!  I have 
recovered but that was a genuine panic.  Potentially about 90 megs of os9 
stuff gone forever.

> On Wed, Oct 3, 2012 at 12:20 PM, Gene Heskett <gheskett at wdtv.com> wrote:
> > On Wednesday 03 October 2012 11:55:51 Retro Canada did opine:
> >> For HDB-DOS, the offset is 3 byte long. So I believe it can be
> >> $FFFFFF-(256*630) maximum.
> > 
> > That is an HDBDOS restriction.  If running nitros9, and your bootfile
> > includes /sh.dd, then be aware that the dmode utility can be used to
> > make quite a few of the 256 disk sets of rsdos formatted virtual
> > disks available.
> > 
> > For instance, I have 2 1Gb drives on my tc^3 scsi controller.  Address
> > 0 on the scsi bus is my work drive, and is partitioned for $1DBB90
> > sectors as /dd.  That is about 498 megs, using a cluster size of 4.
> > 
> > Normally, a dmode of the /sh descriptor says the offset is also set to
> > $1DBB90.  This is the "wpc=1D ofs=BB90" in dmode.  In the /sh
> > descriptor for the superdriver, the stp value is used as the vdisk to
> > access, so if stp=$80, that is the drive my copy of HDBDOS can boot
> > from.
> > 
> > BUT, until I run out of drive, there is no reason the offsets in /sh
> > cannot be modified (write it on the wall so you can restore) by using
> > dmode to increase this offset value by an additional $27600 for every
> > additional 256 vdisk set you need.  On one of those 4Gb CF cards,
> > that is a huge bunch.
> > 
> > I think what I would do would be to write me a bunch of scripts called
> > dmodesh# where # was the set of vdisks you wanted to look at.

Cheers, Gene
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