NitrOS-9 is a community-based distribution of the Microware OS-9 operating system for the 6809 that was introduced in the late 1970s and sold into the 1980s.
The Hitachi 6309, which contains additional registers and enhanced instructions, is also supported.
Here are the current ports of NitrOS-9 available:
| Computer | Port | Processor |
|---|---|---|
| TRS-80 Color Computer | NitrOS-9 Level 1 | 6809 & 6309 |
| Radio Shack Color Computer 2 | NitrOS-9 Level 1 | 6809 & 6309 |
| Tandy Color Computer 3 | NitrOS-9 Level 2 | 6809 & 6309 |
| CoCo 3 FPGA | NitrOS-9 Level 2 | 6809 |
| Dragon 64 & Tano Dragon | NitrOS-9 Level 1 | 6809 |
| Dragon Alpha | NitrOS-9 Level 1 | 6809 |
| Atari w/ Liber809 | NitrOS-9 Level 1 | 6809 |
| Corsham 6809 SS-50 | NitrOS-9 Level 1 | 6809 |
In order to build NitrOS-9, you need to install the lwtools package which contains an excellent 6809 assembler and linker. Once downloaded and installed, you can build the entire project:
export NITROS9DIR=$HOME/nitros9
make
The result of this are a number of disk images (ending in .dsk) that can be used on real floppy drives, emulators, and DriveWire.
There are two double-sided 40 track DSK images ending in '_ds40_1.dsk', and '_ds40_2.dsk' for disks 1 and 2, respectively. For those with 3.5" 720K drives, an 80 track DSK image ending in '_ds80.dsk' is also included in the distribution.
If you wish to transfer the disk images to a floppy disk for use with a real CoCo, follow the steps below:
-
Download and install the latest version of DSKINI/RETRIEVE at http://www.nitros9.org/
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Insert a blank double-sided floppy in to your drive (we assume B:)
-
Type one of the following commands for 360K 5.25" and 720K 3.5" floppy disks, respectively:
DSKINI /T40 /D B: <diskimagefile>
DSKINI /T80 /D B: <diskimagefile>
Where is the image file you want to transfer to the floppy disk. The image file transfer should start. When it is done, take out the disk and try booting your CoCo with it.
Repeat steps 2-3 for each additional disk.
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Download and install the latest version of fdutils from http://fdutils.linux.lu/
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Once installed, edit the /usr/local/etc/mediaprm file and add the following lines at the end of the file:
"COCO360":
DS DD sect=18 cyl=40 ssize=256 tpi=48
"COCO720":
DS DD sect=18 cyl=80 ssize=256 tpi=96
-
Insert your blank floppy into the drive on your Linux box.
-
Type one of the following commands for 360K 5.25" and 720K 3.5" floppy disks, respectively:
setfdprm /dev/fd1 coco360
setfdprm /dev/fd1 coco720
This assumes your floppy drive is /dev/fd1. You may need to make adjustments to the above commands for your environment.
- After typing the setfdprm command, the floppy drive unit should spin for a second then stop. Type this command:
dd if=<diskimagefile> of=/dev/fd1
Where is the image file you want to transfer to the floppy disk. The image file transfer should start. When it is done, take out the disk and try booting your CoCo with it.
Repeat steps 3-5 for each additional disk.
Unfortunately, many of the FDC chipsets shipping on PC motherboards do NOT understand, and will probably crash your PC when a 256 byte/sector disk read or write is attempted. The Asus M2n-SLI Deluxe board is one such board.
When using DriveWire, the appropriate for your machine .dsk file can be downloaded and mounted directly as a fully read/write virtual disk. Please see for instance the tutorial at http://www.cocopedia.com/wiki/index.php/Getting_Started_with_DriveWire