Jan,

> Folks on the list can correct me if I'm wrong, but Squeak heavily
> depends on doing bitblt's from memory to the screen buffer.
> The bitblt from memory to screen performance of a modern AGP
> based PC video card is as high as 200-300 megabytes/sec

Correct. There is one thing that's interesting as well and that's that
blitting between VRAM directly is again quite a bit faster (since it doesn't
need to go to the AGP bus - compared to the memory speed of a modern
graphics card AGP is slow as hell ;-)

> Some older display adapters had no way to map the screen buffer into
> memory and had to execute graphics processor commands that would 
> take a stream of data written to an I/O port to get the bits to 
> the screen. 

This is exactly what an X-Server does (and the reason why using the XSHM
extension for local display make such a difference on Unix Squeak).

  Andreas