[Coco] Re: problem with New NitrOS9

[Rodney V Hamilton]

In article <40E88EEC.2090907 at charter.net>, 
jadonaldson at charter.net says...
>   I just downloaded the lastest and greatest NitrOS9, dated May, 2004. 
>I copied the
>DSK's over to John's emulator, told it to use Dsik in drive 0 and Disk 2 
>in drive 2. Rebooted
>the emulator and the boot failed.
>
>What did I do wrong??
>
>John Donaldson

The NitrOS-9 distribution no longer supplies single-sided boot disk
images, nor the front-side-only and back-side-only disk images that
the JV and JC emulators both used to emulate double-sided boot disks.
So how did you produce your /D0 and /D2 images?  The "ds40_[12].dsk"
images are double-sided 40Trk disk images, used to create real disks.

Actually, I find it very useful to patch the 720K 80Trk disk image
to use as my /D0, with no /d2 needed.  If you look at the LSN0 byte
at offset $0010 in the disk image, it will be set to $07 to indicate
a double-sided 80trk disk, but if you CHANGE that byte to $06, the
JV and JC emulators will be fooled into treating it as a single-sided
disk with no need to split it into /d0 and /d2 pieces!

However, the boot track will now be mapped to logical track #68 rather
than #34 as the DOS command expects.  There are two solutions:

[1] poke the new starting track number into the DOS command every time
     eg:  POKE &HDF1C,68:DOS

[2] patch the DOS command in the RSDOS rom image to automatically try
    to boot from track #68 if the default track #34 fails

If you use Jeff Vavasour's OS9BOOT instead of the BASIC ROM images,
that can also be patched to auto-try tracks 34 and 68.  I posted both
patches to this list on Oct 26 2003, (message ~#500 or so on GMANE or
get it from the online maltedmedia COCO archives.)

I hope this helps.

-- 
Rodney V Hamilton
"I've been pressing my HELP key for 2 hours and no one's shown up yet.."