From mboxrd@z Thu Jan 1 00:00:00 1970 From: rochkind@basepath.com (Marc Rochkind) Date: Mon, 16 Jan 2017 10:49:06 -0700 Subject: [TUHS] Article on 'not meant to understand this' In-Reply-To: <3556CAD6-0DFE-4F6A-B897-0C4D59ACAF2E@me.com> References: <20170116014444.GA32261@minnie.tuhs.org> <20170116031510.GB6647@mcvoy.com> <3556CAD6-0DFE-4F6A-B897-0C4D59ACAF2E@me.com> Message-ID: "... one lacks true understanding of operating systems until ..." With this as the standard, I have a false understanding of operating systems. So, I am ready for the post-truth society we are entering. Are you? ;-) On Mon, Jan 16, 2017 at 3:11 AM, Brantley Coile wrote: > I agree that one lacks true understanding of operating systems until one > codes a process switch. My first was in 1979 on a home brew 6800 (not > 68k). It was made easier by the fact that the 6800 saved all 64 bits of > registers on each interrupt. All that was necessary was to wire a timer > interrupt and change the value of SP in the handler. > > Brantley Coile > > > Sent from my iPad > > > On Jan 15, 2017, at 10:15 PM, Larry McVoy wrote: > > > > Yeah, saw it. I'm of the opinion that you aren't really truly an OS > > person unless you've written a context switcher. I wrote one for a > > user level threading package I did for Udi Manber as a grad student. > > I did most of the work in C and then dropped to assembler for the > > trampoline. > > > > It's really not that complicated, I think people make it out to be > > a bigger deal than it is. You're saving state (registers), switching > > stacks, and changing the return address so you return in the new > > process. > > > > Well, not that complicated on a simple machine line a VAX or a 68K > > or a PDP11. I sort of stopped playing in assembler when super scalar > > out of order stuff came around and I couldn't get the mental picture > > of what was where. > > > >> On Mon, Jan 16, 2017 at 11:44:44AM +1000, Warren Toomey wrote: > >> http://thenewstack.io/not-expected-understand-explainer/ > >> > >> in case you haven't seen it yet. > >> > >> Cheers, Warren > > > > -- > > --- > > Larry McVoy lm at mcvoy.com > http://www.mcvoy.com/lm > -------------- next part -------------- An HTML attachment was scrubbed... URL: