NitrOS-9 is a real-time, process-based, multitasking, multi-user, Unix-like operating system for the 6809 and 6309 processors. It runs on TRS-80 Color Computer, Radio Shack Color Computer 2, Tandy Color Computer 3 and Dragon 64. The original OS-9 was created in 1979. NitrOS-9 is the modern equivalent of that OS, and includes advanced features like support for up to 2 MB RAM and 4 GB Hard drive partitions. It is still being developed, and support is available in many mailing lists and forums.
That is what we call commitment.
It’s worth reading about the 6[83]09 processor as it’s regarded as the best 8-bit processor ever made. It’s highly orthogonal and has separate system and user stacks, making it the only 8-bit consumer CPU that can multi-task natively without horrible hacks (the 6502 has a fixed-position, single stack). NitrOS-9 is therefore a *real* operating system, like we would think of one such as UNIX, rather than an 8-bit look-a-like like GEOS.
Indeed, the 6809 paved the way to the 68000, with a pretty much orthogonal ISA too, yet with different mnemonics (for obvious reasons).
Btw, the Atari ST’s IKBD (internal keyboard’s CPU) is a Hitachi 6301, which is… a 6801 equivalent. It would have been great to have a 6309 instead.
That wouldn’t have made much sense, the 6801 is a microcontroller, not an ordinary processor., with internal RAM and ROM just like the equivalent Intel microcontrollers used as keyboard controllers.
Indeed, but it would have been cool to have a MCU equivalent of the 6309.
https://en.wikipedia.org/wiki/Hitachi_6309 : Later, Hirotsugu Kakugawa posted details of the 6309’s new features and instructions to comp.sys.m6809. This led to the development of NitrOS9 for the Tandy Color Computer 3.
And some people still discover things about them : https://x86.fr/investigating-the-halt-and-catch-fire-instruction-on-motorola-6800/
“6502 has a fixed-position, single stack”
Yes, but 6809 contained 3x transistors and sold for 6x the price, a quite big tax. Moreover 16 bit designs were on the home stretch.
The 6502 is the outlier — It was specifically made to be ridiculously simple and cheap. In 1975 it cost $25(!) one-sixth of the 6800 or 8080 at the time.
“In 1975 it cost $25(!) one-sixth of the 6800 or 8080 at the time.”
True, but its low price was not due to “ridiculously” simpleness (it had only ~15% transistors less than 6800) but rather a more advanced design and the use of projection masking that lead to a big leap in yeld.
In comparison before 6502 launch in August Motorola was selling 6800 at 175$, in October price dropped to $69 and by the following May you could buy it with 35$.
One small nit -25% not -15%
Philips CD-I sported some OS-9 derivative.
Phillips CD-I used OS-9/68k