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For questions regarding the Motorola 6809 microprocessor.

11
votes
3answers
350 views

Motorola 6809 two stacks design

I'm an assembly newbie, but I'm curious about why the designers of the 6809 choose to use 2 stack in the microprocessor architecture. What is their original intent? The Wikipedia page says "a user ...
29
votes
4answers
5k views

What limited the use of the 6809 CPU in personal computers?

Why did manufacturers of home computers avoid using the 6809 CPU? I realize that the Z80 and 6502 had a 3- or 4-year head start in availability. But once it did become available in 1978, I don't ...
7
votes
1answer
79 views

HD63B03R timer interrupt frequency

I am trying to maintain an old procuct for my employer, based on an HD63B03R which is a 6800-style micro. The crystal on the PCB generates a 4.75MHz clock. I believe from the data sheets found on t'...
13
votes
1answer
312 views

Calculating the time for a CPU cycle

As a learning exercise, I'm writing an emulator for the 6809 CPU. I'd like to simulate the speed of the CPU. I know the Motorola 6809E runs at 0.895 MHz and 1.79 MHz on the Color Computer 3. How do I ...
15
votes
1answer
387 views

Motorola 6809 Stack Blasting

I've seen several mentions of a "Stack Blasting" technique for copying memory quickly on the 6809. What is it? How does it work?
33
votes
3answers
798 views

Advantages of a Hitachi HD6309 versus a plain Motorola MC6809

Hitachi was a second source for the Motorola 6809 Micro Processor. The 6309 had many secret features. What advantages does the HD6309 have over the MC6809?