[plex86] X Windows in plex86

[Kevin Lawton]

Since some people asked about running X in plex86:

Currently, there's a simple hack to periodically copy over
the text buffer area of memory to the internal memory of the
VGA adapter emulation.  In text mode, we can get away with
this.

For latched planer graphics mode (640x480x16colors), this
can't work, because the memory doesn't work in a
what-you-write-is-what-you-read mode.

So, for this mode, we need to trap accesses to the
video memory area and redirect them to the VGA
emulation.  I just didn't get around to doing this
yet.  Will do soon.  Anyways, as you can imagine
this will not be very efficient as each memory
access would be trapped and shuttled between
monitor/guest and host spaces.

Ideally, a special guest OS specific driver would
be written to handle video.

Anyways, we'll get the graphics stuff working soon.

-Kevin