[Coco] Mission Accomplished!

Steve Bjork 6809er at srbsoftware.com
Thu Mar 1 18:37:49 EST 2012

While the 6809 was the big "Pro" for the CoCo, the even bigger "Con" was 
the Bit-Map graphics system for games.  There was too much screen memory 
that needs to updated on each game frame and why most CoCo games are 
slow.  The Atari graphics system allowed for dramatic updates with very 
little memory updates.  (Good for any CPU.)

Yes, putting a 6309 CPU will improve some stuff.  But its the graphics 
system that limits most games.


On 3/1/2012 1:08 PM, Boisy G. Pitre wrote:
> On Mar 1, 2012, at 2:48 PM, Steve Bjork wrote:
>> As someone that programed "a few games" on both CPUs, the main advantage of the 6809 over the 6502 is handling large data-types.  The other problem with 6502 is the limited support for Object-oriented programming.  6809 and 68000 series CPUs are geared for Object-oriented code, even in Assembly.
>> The 6502 does lend itself to very tight and fast code.  (Important to fast games.) So, most (re-coded) games will not see much (if any) improvement because the CPU was changed to a 6809.
> Steve, I would think that there would exist inherent advantages in having a processor with more registers and a richer instruction set.  Granted, the Atari graphics and sound hardware make for the CPU having to do very little, but with fewer responsibilities, I would imagine that the 6809 could edge out the 6502.  As I stated in the other post, having a 6309 would definitely be an advantage over the 6809, as it is in the CoCo itself.
> Anyway, it's now possible to find out.
>> Steve

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