4 ms·

You might enjoy this paper, which is included with a cycle-accurate 6809 FPGA implementation: https://github.com/cavnex/mc6809/blob/master/documentation/super6

You might enjoy this paper, which is included with a cycle-accurate 6809 FPGA implementation: https://github.com/cavnex/mc6809/blob/master/documentation/super6809.md https://github.com/cavnex/mc6809/blob/master/documentation/s... I particularly liked how it covered his thoughts on why he'd avoid implementing a Hitachi 6309 instead. There's a bit more on the main README, as well.

protomyth 5y ago
Hitachi did love to put their own touch on things. I do wish they had kept going with the SH processors.
cmrdporcupine 5y ago
I've read this before, and I like this bit at the end: "My knee-jerk sense here is that the 6809 was (nearly) the last big combinatorial non-microcoded CPU for a good reason. Some of us adore it, but there's a pragmatic limit to attempting to make a 'super' version of it; the supercharged "thing" quickly ceases to be a "6809" any more." I feel like the same thing applies to people who have tried to extend the 6502 into 32 bits, etc. No matter what you do it just doesn't end up being 6502ish, really. The genius with those processors was what they could do in a single cycle, with a minimal transistor count, fast interrupts, and with a one-byte opcode. It sucks not being able to address more than 64k but everything I've seen that extends that ultimately ends up being awkward and not 6502ish (including the 65816 in this)