[sdiy] Re: Bottom Ten ICs

[Colin f]

> You mean TMS9900, a brilliant processor IMO.
> The whole address space works as register space, no stack 
> pointers and stuff
> just use a other memory area for your registers instead.
> Really a treat to code for :)
> It was also fast,  about the same performance as a 68000 @ 4Mhz.
> Keep in mind it dates from the late '70s.

Yep. A great processor.
Then TI built the 99/4a round it, and had only 256 BYTES of RAM directly
accessible by the CPU.
The rest of the stock machine's RAM was the 16k video RAM.
For the CPU to access it, all read/write requests had to go through the
video controller.
D'oh !
That's why they were so slow. Not to mention the stupidity of using an 8 bit
data bus when the CPU was 16 bit.
Still, I do enjoy a nice game of Parsec now and again ;-)

Colin f