[Coco] Run NitrOS-9 on the JVC/Collyer Coco3 emulator
robert.gault at worldnet.att.net
Wed May 18 09:04:57 EDT 2005
Getting the NitrOS-9 images onto a real Coco system can be a problem and
some people may want to stop on a PC with an emulator. The most
universal emulator that can run all versions of NitrOS-9 is MESS. The
simplest way to get the images to work with MESS is to change the
extension from .dsk to .os9.
The latest version of the Vavasour / Collyer emulator Coco3 6309 v1.91B
can also run NitrOS-9 with a little help. The most powerful version of
NitrOS-9 is the Level-2 6309 and the full program is distributed on an
80 track double sided disk image. So let's use this as an example.
The Collyer program can be obtained from RTSI
ftp://www.rtsi.com/RSDOS/incoming/ in the johncollyer_website.zip file
as ver19.zip. Os9boot.mor (a necessary file) can be obtained at
http://www.vavasour.ca/jeff/trs80.html#coco3 . NitrOS-9 can be obtained
from http://www.nitros9.org .
Step 1: Rename os9boot.mor to coco3.rom and install it with the
JVC/Collyer emulator. This rom will boot directly to OS-9 using the disk
image installed on drive0. However, one byte of the file must be changed
with an editor so it can find the boot track on a double sided image.
Step 2: Use a raw file editor and look for the patter $15 CC 22 01 ED
(near the start of the file) and change the $22 to $44. Now we need to
change the NitrOS-9 .dsk image to indicate that the disk is single sided
instead of double sided.
Step 3: Use a raw file editor to change the 17th byte of the .dsk image
from $03 to $02. This will tell OS-9 the image is single sided.
Now you can start the emulator and NitrOS-9 will automatically boot.
There may be one final problem with the emulator as it needs DOS not
Windows to run NitrOS-9 correctly. Not all Windows system have a DOS
mode. You may need to run emulation from a boot floppy on such systems.
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