[Coco] "Sprites" on CoCo?

[Glen Hewlett]

Hi John,

I just went through this problem myself a few months ago while transcoding Pac Man.  I first did the quick and dirty method of copying the data byte by byte which is slow, but was good enough to see if the code is working.  Then I tried stack blasting which is a cool topic where you setup the U & S stack pointers to copy data from the stack example PULS D,X,Y and PSHU D,X,Y to the screen RAM.  I was doing this using all the registers including the CC register which meant I had to turn off the IRQ and FIRQ while stack blasting.  Turning off the FIRQ, even for the small amount of time to blast the sprite on the screen can still add extra noise if you use the FIRQ for audio.  Stack blasting is fast but still not as fast as compiled sprites.  I just thought I’d let you know that I did test them so you don’t have to go down that road.  To get an idea of what a compiled sprite is you can see a post on my blog (shameless plug) about them.

https://nowhereman999.wordpress.com/2017/04/12/zilog-z80-to-motorola-6809-transcode-part-021-compiled-sprites-are-faster-then-stack-blasting/ <https://nowhereman999.wordpress.com/2017/04/12/zilog-z80-to-motorola-6809-transcode-part-021-compiled-sprites-are-faster-then-stack-blasting/>

Another benefit of compiled sprites vs. Stack blasting with all the registers is there’s no need to turn off the IRQ and FIRQ.

Good luck on your sprite journey,
Glen


> On May 8, 2017, at 1:00 PM, John Lochey via Coco <coco at maltedmedia.com> wrote:
> 
> Hi all,
> I have been thinking about Sprites (from my days with the Commodore).
> Is such a construct available within the CoCo world?
> I am early in my CoCo education, so sorry for a newbie question.
> 
> 
> Johnny
> 
> 
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