Quote Originally Posted by ncherry View Post
I just had a look at the Euro 1 and I now see how Frank comments relate. He is correct the 6809 has no RAM internally. So you'll need to add RAM and the decoding for it. Also the 6802 ROM code won't run on the 6809. So it's not a drop in replacement.
But the Eurocom has 1 KB RAM of its own starting from $0000. The lower RAM isn't used because the 6802 will use its internal RAM. The PCB on the picture in the book is very small. IMHO it is just a 6809 plus maybe two IC under it, certainly no extra RAM.