Path: utzoo!utgpu!water!watmath!clyde!wtr@moss.ATT.COM From: wtr@moss.ATT.COM Newsgroups: comp.unix.xenix Subject: Re: Writing directly to screen memory o Message-ID: <26364@clyde.ATT.COM> Date: 13 May 88 13:44:02 GMT References: <274@gandalf.littlei.UUCP> <47900007@uxe.cso.uiuc.edu> Sender: nuucp@clyde.ATT.COM Reply-To: wtr@moss.UUCP (Bill Rankin) Organization: AT&T Bell Laboratories, Whippany NJ Lines: 53 In article <47900007@uxe.cso.uiuc.edu> mcdonald@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@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) email address: ...![ ihnp4 ulysses cbosgd allegra ]!moss!wtr ...![ ihnp4 cbosgd akgua watmath ]!clyde!wtr =====================================================================