disassembly of 6803 code

[Nigel Duckworth]

Arnaud wrote:

> I downloaded the data sheet for a MC6803E processor. I assume there will
> be some differences between the processors but also that they use the
> same instruction set?

>From memory the 6803 uses the 6800 instruction set but don't quote me on that,
it's been a long time since I played with these.

> Where/how do I start to disassemble the code? Would a disassembler be of
> any good?

I have no experience of disassemblers but have you thought what you will do 
with
the code when you get it?

> This raises another question, how does one map the external memory
> space? The data sheet confirms the external memory at $00FF-$FFF0 but
> how to figure out that the timer is at $2000-$2007, for example?

The address of the timer was chosen by the designer of the electronics, it uses 
a range of addresses decoded in hardware.

Hope this helps.

Nigel


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