On 2/26/10, Mark Tapley <mtapley at swri.edu> wrote: I may have to keep my eyes out for that one. I'm much less informed about the 6809 than any of the other contemporary processors. Hmm... I haven't read anything by Barden, so I'm merely commenting on your comments, but I do remember that back in the day, besides a "better" register scheme, the one thing that really made the 6809 stand out (from my 6502 world) was its ability to render position-independent code. I didn't need it often when I was programming the 6502 daily, but occasionally, I did wish for it. Perhaps the lack of attention to that in the book is due to a lack of perceived utility for it? When the 6502 and Z80 and 6809 ruled the earth (or at least the hobbyist corner of it), multitasking operating systems weren't the norm. I know OS/9 stands out, but until you jump up to early UNIX super-micros, there's not much else in the field that was commonly available (the PDP-8 had RTS-8, but compared to a basic OS/8 setup, RTS/8 was strange and rare). The vast majority of micros had "operating systems" (by a very wide definition) with fixed-position memory maps. There was little need to be able to shuffle your code from one spot in memory to another. Even on larger systems, like the PDP-11, MMU hardware did that sort of mapping for you (despite the fact that PIC is easy to write for the -11). As for the lack of "advanced software-management tool[s]", most of the books that I've read from the late 1970s and early 1980s fall into that category. I don't think I learned anything "better" than flowcharts and coding sheets until I hit the minicomputer world in the mid-1980s (it sure wasn't any different when I took my first programming course in college in 1984 - flowcharts were a mandatory part of the homework and were graded quite rigorously). By the late 1980s, I remember a change in the weather with articles in Amiga-centric magazines on programming the 68000. See if you can find Transactor magazines (or PDFs of them). Those might be "modern" enough in their approach to feel more friendly. The instruction set's not the same, but code organization and concepts are analogous. Perhaps. With 1970s docs, my feeling of remembering those days is that 8080 and Z80 tutorials and guides were "stiffer" than 6502-related material, but I'll easily admit those memories are somewhat biased because I spent lots more time seeking out and reading 6502 publications in depth. The 6809 stuff, though, kinda went by unexplored by me since I had no hardware to tie to it. -ethan