[Coco] coco 2 vs coco 3

Nick Marentes nickma2 at optusnet.com.au
Mon Sep 29 17:32:29 EDT 2014


The CoCo3 also has the ability to run at double the speed of the CoCo1/2.

This was a good move in the design of the CoCo3 but unfortunately didn't 
go far enough.

If there is one upgrade that the CoCo3 really needs is CPU speed. We can 
say that it needs a sound chip or it needs sprites but really, good 
programming can/has provided this. What it needs is speed to do these 
better.

Think about it...

The CoCo1/2 had a clock of .89Mhz and it's highest resolution graphics 
occupied 6K of RAM.

The CoCo3 clocks at 1.79Mhz (2X) which makes handling this 6K area much 
quicker.

But the new CoCo3 graphics modes (320x200 and 640x200) occupy 32K. 
That's a 5X RAM usage with only a 2X CPU speed increase from a CoCo1/2.

The CoCo3 should have come with a 4X speed increase (3.56Mhz) to keep 
things in balance.

Anyone who can discover a way to boost the CPU speed will immediately 
boost the CoCo3's capability for not only games but also OS-9 (NITROS9). 
The bottleneck is the fact that the CPU is too closely tied to the GIME 
chip timings... but there has to be a way.

Nick



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