UNIX PC Graphics Questions
Bill Carpenter
wjc at ho5cad
Thu May 12 00:20:28 AEST 1988
In article <2271 at inco.UUCP>, todd at inco (Todd O'Connell) writes:
>2) Is there any way to directly access screen memory? I would like to
> bring up a segmented graphics package on my 7300 but find it a little
> abhorrent to do pixrect ops to display a single pixel in a vector draw
> routine. I would use the graphics driver except that I also want to
> do some raster work and I don't want to waste 16 bits/pixel for a b/w
> display.
The screen memory on the UnixPC is a whole different set of chips from
regular old program memory. To access it, you'd have to get right
down there to the hardware, and Unix won't let you do that except in a
privileged kernel mode. If you were especially clever, you could
write a device driver for a device that fiddled with screen memory
directly. But, when I say clever, I mean with a capital C. Also, you
wouldn't be that far ahead, since you would still have to make a
system call (which is what you're already doing). Good chance of
clobbering the rest of the system as well.
BTW, if you do write that kind of device driver (or find some other
way of writing to an arbitrary spot on the screen without regard to
the window boundaries, etc), I'd give you at least a nickel for a
copy.
--
Bill Carpenter
(AT&T gateways)!ho5cad!wjc
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