[GEM Development] The OpenGEM Interviews

[John Elliott]

: EGA had acceleration? News to me. Or was this specific to Amstrad EGA?
: Which would still be news to me, but slightly less surprising. I didn't
: think PC GUI accelerators came along 'til another few years after that.

  It probably wouldn't count as acceleration in the modern sense (it doesn't
have hardware line draw, or bitblit, or anything like that). What I was
referring to was the range of access modes, and the 32-bit data latches
which allow a blit to copy all four planes in one go. 
  For example, a typical flood fill algorithm works by checking whether
adjacent pixels to the current one are the colour that should be replaced.
On the PC1512, this requires accessing each plane in turn and comparing the
contents with the right bit of the colour to match. On the EGA you just load
the colour match register and do a single read of video RAM; pixels in the
required colour come out as 1 and the others come out as 0.

: > the PC1640 still has the original PC1512 video circuitry (disabled) as
: > well as its own Paradise EGA chipset.
: 
: Good grief! I never knew. However did you find that?

  I stumbled over it by accident.

-- 
John Elliott