🚀 go-pugleaf

There are two main reasons that os/2 doesn't support VGA (and SVGA)
modes in a window...

first, (s)vga modes  take up a lot of memory (up to 1 meg generally,
newer cards use even more memory).... To support virtualized vga modes
would mean that os/2 would have to have at least that much memory
available FOR EACH WINDOW! This would eat up resources faster than
godzilla could trample Tokyo.

Second, most vga modes use bit planes.  For those not familiar with bit
planes, they are simply a mechanism for accessing more than one byte of
video memory at a time, by compromising on whether you want to access
one pixel color on the screen, or access a group of pixels quickly.

One write to a bit plane could update several bytes of video memory,
which would recquire os/2 to modify those bytes in its own bufffer.  The
result would be the speed of the original apple ][...  Much of the
success of vga is due to the fact that it is so quick to do pixel writes
and copies.

Other bitplane modes are supported in OS/2 (ie EGA), because of a
"trick" the designers used to support them... The designers took some
left over memory at the end of your video cards buffer and uses it to
virtualize writes to the screen... notice, however, that this is seems
to be enabled only with the "scaled image" option, and it is VERY
slow...

As I have said over and over, it seems that the biggest flaws in OS/2
are really the flaws of the PC architecture, which was not designed as a
virtual machine or meant to be used for mult-user,multi-process
environments.

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OS/2: Mainframe power for todays desktop

-- 
John Winthrop                    | "The only solution is:
johnw@wixer.cactus.org           |  cd /
cactus.org!wixer!johnw           |  rm -rf ."
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