[Coco] IRQ question

[Mark McDougall]

On 3/02/2017 7:29 AM, Simon Jonassen wrote:

> I beg to differ...
>
> you can definately OPTIMIZE it to make it run in realtime.... !

I'll second Simon on this one.

If Sockmaster can get Donkey Kong running at full speed, then I believe 
Pacman can be made to run full speed as well. I'd even venture to say 
that Pacman's graphics hardware is less demanding than DK; certainly 
there's (a lot) less sprites than DK is capable of. For instance, DK 
employs a while extra MCU to move/update sprites!

Having said that, it may very well be the case that it is beyond any 
sort of auto-translation, and may instead require a lot of hand 
optimisation, so much so that renders the auto-translator superfluous? 
Pure speculation on my part.

As for the immediate concern, sprites... plenty of optimisations not 
just strictly to the code, but the overall operation. Simon is probably 
the best one to talk you through code optimisation on the 6809, if not 
sprites in general. You may need to consider things like pre-shifted 
and/or pre-flipped sprite data, dirty rectangles, etc etc above and 
beyond pure instruction optimisation.

IMHO it's going to be a lot more work than getting a half-decent 
auto-translator coupled with generic sprite emulation. But then, that's 
what makes it worth doing; you learn a lot more and it's a greater 
achievement at the end!

And FTR, Knight Lore runs on a 3.528MHz Z80 (albeit no sprites to 
emulate) and it runs *faster* on the Coco3 than the original! So hang in 
there!!!! :)

Regards,

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