[Coco] Space Invaders - Translated from Intel 8080 to Motorola 6809 for the CoCo 3

[Mark McDougall]

On 4/01/2017 4:16 AM, Glen Hewlett wrote:

> I think by hand is the best way to do the transcoding in the end.

I've now 'completed' 3 projects; one 6502->6809, one Z80->6809 and one 
8080->6809. Also half-way thru Z80->68K.

I would say there's definitely some merit in automated translation. I 
found myself repeating the same instruction sequences over and over when 
doing it by hand. Of course you'll never get an automated process 
perfect or optimal, so there'll always be manual tweaking, but I would 
say it could very well save some time.

Automation would work best when porting to a more capable system, eg. 
Z80->68K. In fact, I'm thinking of redoing portions of said project 
because I wasn't quite consistent in the early stages with my register 
mappings, and perhaps automation would help with this.

> In the end, I probably did end up going through it line by line
> anyways since there are some many registers and things that need
> tweaking.

Yeah there's certain aspects that just can't be automated.

> MAME debug mode is so useful for doing
> this type of troubling shooting.  I’d be lost without it.

MAME/MESS is an under-rated and under-utilised diagnostic, debugging and 
development tool. Many, many years ago I used it to identify a faulty 
DRAM chip on my Juno First PCB, by patching the driver to simulate a 
faulty chip until I got the exact same display on MAME as I saw on my 
cabinet!!!

Regards,

-- 
Mark McDougall
<http://retroports.blogspot.com.au>