Path: utzoo!hoptoad!well!rab From: rab@well.UUCP (Bob Bickford) Newsgroups: alt.hackers Subject: Re: CS curriculae (was Re: Distributed Hacking :-) Message-ID: <15504@well.UUCP> Date: 14 Jan 90 07:48:18 GMT References: <5458@udccvax1.acs.udel.EDU> <1146@crash.cts.com> <90011.150343CMH117@PSUVM.BITNET> Reply-To: rab@well.UUCP (Bob Bickford) Organization: Whole Earth 'Lectronic Link, Sausalito, CA Lines: 41 Approved: moderator Ahem. Yes. Well, anyway, as I was saying, I have my own definition of 'hacker', which I've twice had published in article form in a local computer rag (MicroTimes): Hacker: "Any person who derives joy from discovering ways to circumvent limitations." I grant that this can be stretched to include the juvenile criminals we see so much press about, but I really don't give a damn about them: I'm interested in _true_ hackers: Artists of Technology, Riders of the Third Wave. And *that*, I think, is what this group is about. Obligatory hack story: In our product, the graphics processor (34010) is the only way to access the many megabytes of VRAM which contain the images. But, there's only one Host port on the beast, and we're running a multi- tasking OS on the '186 that sometimes wants to DMA several megabytes in or out of the '010. Which means that for long times (over a second in some cases) we can't talk to the '010 (like, send it graphics commands). Unacceptable. So, I hacked up a way of 'suspending' the DMA, which also means I have to preserve the '010 host port state (NOT EASY!), and then I sneak in the command and put everything back. Unfortunately, the same '186 register that contains the DMA control bit I want to use, has the status bits for the timer interrupts (which I *must* *not* corrupt, even by one tick). So, I had to put in a little kludge that looks to see if the timer(s) are about to expire, and waits if so, before munging that register (so that those bits are in a known stable state). -- Robert Bickford {apple,pacbell,hplabs,ucbvax}!well!rab rab@well.sf.ca.us /-------------------------------------\ | Don't Blame Me: I Voted Libertarian | \-------------------------------------/ -- Robert Bickford {apple,pacbell,hplabs,ucbvax}!well!rab rab@well.sf.ca.us /-------------------------------------\ | Don't Blame Me: I Voted Libertarian | \-------------------------------------/