Writing directly to screen memory o

[wtr at moss.ATT.COM]

In article <47900007 at uxe.cso.uiuc.edu> mcdonald at uxe.cso.uiuc.edu writes:
>>Has anyone ever written directly to the screen memory with UNIX or
>>XENIX on a PC?  I know that I probably open /dev/mem and start 
>>writing at the ega address space 
>
>I am also interested in this. It appears that the cheapest way to
>get access to a 386 operating system and good C compiler is some flavor
>of Unix. I need, however, to be able to write direct to the screen
>and use the IO ports on the graphics board to do animation graphics.
>
>Doug McDonald  (mcdonald at uxe.cso.uiuc.edu)

First of all, thia article will refer to microport unix.  This was
the only group where i could find this message and thus am posting
this follow-up here.  I also think that the concepts expressed here
could be usefull in a xenix system, of which I know little specifics
about.

Now, for the meat ;-)

Doug-

Microport Unix V/AT (and I believe their 386 V.3 also) has a process
called "shmcreate" which you run at bootup.  It locks a block of
memory as a shared memory resource.  By using this on the video
memory space, you can allow user programs (at the console) to access
the memory space directly as an array in memory.  (making life mucho
easier for graphics implementations :-)

I have a set of graphics primitives that currently run on this
machine. (microport V/AT 2.3.0-L) (point, line, bit mapped character
set, stroke fonts for scalible characters, boxes)  FULL credit for
these routines goes to:

	dave lewis 
	arpa!umix.cc.umich.edu!m-net!dtlewis!lewis

I'm currently looking at implementing some other basic primitives
such as an elipse, pixel read, and a fast flood fill.

If I recall, doesn't Xenix also support a set of graphics routines
as part of the SCO release for the 386?  That may be the way to go.

good luck!

=====================================================================
Bill Rankin
Bell Labs, Whippany NJ
(201) 386-4154 (cornet 232)

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