6809 Monitor

[jim stephens]

On 10/2/2018 12:51 PM, Lawrence Wilkinson via cctalk wrote:
> On 02/10/18 21:24, tim lindner via cctalk wrote:
>> Does anyone have source to a 6809 monitor program?
>>
>> I'm looking for something I can make work in a CoCo.
>>
>> Functionality I'm looking for is something that will let me read and
>> write to memory.
>>
> There is a listing of ASSIST09 in this Motorola book: 
> http://geneslinuxbox.net:6309/gene/Genes-os9-stf/MC6809-MC6809E%208-Bit%20Microprocessor%20Programming%20Manual%20(Motorola%20Inc.)%201981.pdf
>
> This might be overkill, as it has single-step, breakpoints etc.
>
> If you type it in, note that the listing omits the second and 
> subsequent hex bytes for constants (FCB) !
>
> LJW
>
If you look at page B-65 (pdf 189) where it mentions "Start NMI 
Timeout", there is a bit of hardware you have to add to the design, and 
set up and control the NMI.  The hardware counts cycles and applies the 
NMI right after you go to the opcode to be traced, and sends you back 
into the monitor via NMI.

I did a quick scan and didn't see what board they assume for a reference 
design which may have the NMI trace part of the board.

We had an option board which would kill the main firmware and add a 
debugger, this hardware, and a serial port to a controller we had, which 
turned any board into a debugging system.  There was another slight mod 
and a diagnostic firmware we also had on an addon board to allow testing 
the peripheral we were controlling, and run diagnostics on other hardware.

I had a lot of fun getting this monitor going, and a friend implemented 
a Forth for the diagnostic system for scripting.

Thanks
Jim