And with well conceived video hardware, the 6809 could do a lot!
The arcade game DEFENDER is a single, pixel pushing 6809 drawing to a single frame buffer. Notably, that hardware included a signal when the CRT raster hit the middle of the screen!
This made a single bitmap frame buffer function as a double buffered display, without the cost of having to clear an entire screen in between frames.
Very efficient.
https://m.youtube.com/watch?v=wAKxa5C9jHY&t=3122s&pp...
You can skip through that to find some of the real action. Quite impressive!
Notably, a 6800 does the sound. One sound at a time generated parametically.
There have been some experiments to drop a 6809 into other 8 bit systems. One was created for the Atari, but no real software pushing limits was ever created.
I would think one of the better transplants would be the Apple 2. It has a video system that does not interrupt the CPU. That would operate much like the Williams hardware, minus the handy screen addressing.
The 6809 is my favorite 8 bit CPU.
While I have not programmed a 6309, I would enjoy it immensely.
Maybe I can stick one onto a card in my Apple one day.
Since I was a relatively impoverished college student and had no prior experience with computers when I got my first, a 4k 6809-based Tandy Color Computer, I learned Coco BASIC and then 6809 assembly language (using Radio Shack's ROM cartridge-based Assembler/Editor), I had no inkling how spoiled I was. The Coco's Extended Color BASIC was quite advanced for the time (as compared to the stock ROM BASIC's on comparable micros) and the 6809's ISA was leagues ahead of the 6502 and Z80. I had no idea until much later (post 8-bit era) how relatively primitive the ISAs were on the 6809's 8-bit peers. Since it was all I knew, indexed and program-counter relative addressing just seemed like the obvious natural way of things.
I also didn't understand what was meant by "orthogonal instruction set" when I read the term in Osborne's 6809 book. I just thought every instruction and addressing mode for each register and stack pointer would always have a complete set of its logically-implied counterparts in all CPUs! :-) Oblivious to how fortunate I was in these ways left me feeling especially jealous of the dedicated graphics and sound hardware of the Atari and Commodore 8-bits.
Learning on the 6809's advanced architecture along with the multi-tasking, multi-user, UNIX-like OS-9 operating it enabled, left me uniquely well-prepared for the future of computing in ways other popular 8-bit micros couldn't and I never even appreciated it at the time.
The CoCo 3 ended up being a pretty great machine, but too late.
I had a bit of a blast programming that one briefly in one byte per pixel mode! On NTSC models, one can set the 640 pixel, 4 color mode or 320 pixel, 16 color modes and use a composite display to get basically 256 artifact colors!
I had only a cassette and limited time. All I managed to do was some nice fractal plots, and the like in assembly language.
Today, we have a fair number of good productions on that machine, though surprisingly few make use of the excellent composite modes.
Yeah, the whole setup, if one had it, really was a great education.