Re: How true...

[heuser.marcus@freenet.de]

Michael J. Mahon schrieb:
>
> The only "ultimately misguided" aspect that Cleaver refers to is the
> consumption of 85% of the 6502's time with video generation, leaving
> only 15% for computation.  For a "TV Typewriter" this seems like a
> very reasonable tradeoff--after all, it was intended to be a terminal
> for *another* computer, and using a 6502 saved a 6545 video controller.
>
> The Spectrum/Timex sub-$100 computers used a similar approach to video
> generation with a Z80, and though their speed while displaying was never
> great, it was adequate to interest many users.

The Atari VCS 2600 game console had a somewhat similar approach
with a 6507 cpu (a 6502 variant with 4K address space). Primitive
but flexible and therefore interesting.

While in vertical blank period the cpu could be used for game play
mechanics while the few available cycles in horizontal blanking
had to be used to change hardware registers (and thus generating
the picture).

bye
Marcus