Like I said in my previous post, I've been working on this project for about a month, but the idea came to me years ago. You see, I'm from the generation where home computers were THE THING in the 1980s. There was no single operating system... companies like Atari, Commodore, Tandy and others had their own computers, each running their own software on their own microprocessors. The 6502 was the popular kid on the block, inhabiting the Atari, Commodore and Apple II systems. The 6809 was more powerful, but for some reason was relegated to the lone CoCo (which I grew up with).
The thing about the CoCo was that despite having the 6809, it was underpowered in other ways. Tandy was too cheap to put in a decent sound chip or graphics hardware. The 6809 pretty much did EVERYTHING, and that put the CoCo at somewhat of a disadvantage. Meanwhile, 6502 based systems like the Atari could plod along with a less powerful microprocessor because they enjoyed some great graphics and sound hardware, which could do the heavy lifting.
So fast forward several decades later. The retrocomputing scene is hot and fun, and everyone's looking for something cool to do with these home computers. I'm thinking: why not bring the power of the 6809 with the great hardware of those other computers? After all, we have NitrOS-9 on the CoCo, a super nice multitasking, multiuser operating system. I began studying the 6502 and found it remarkably similar to the 6809 in several ways. Others have made similar observations, but I only found one person who actually bothered to put a 6809 into a 6502 computer. It was a UK101, and he did a little blurb about it on his page, but didn't take it any further.
With someone actually doing it, I knew it could be done, but I wanted to take it a step further. I wanted to interface the 6809's brother, the 6809E, to a more elaborate 8 bit system. I chose the Atari as a first step because of their graphics and sound hardware, and so I acquired an Atari XEGS off of eBay and began the process.