November 2018 - COFF - www.tuhs.org

by Dave Horsfall

Almost forgot... We lost Sir Maurice Wilkes FRS FREng on this day in 2010; he was known for his work on EDSAC, microprogramming, etc. -- Dave

5 years, 4 months

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In memoriam: Ada Lovelace

by Dave Horsfall

Augusta Ada King-Noel, Countess of Lovelace, was lost to us in 1852 from uterine cancer. Regarded as the first computer programmer and a mathematical prodigy (when such things were unseemly for a mere woman), she was the daughter of Lord Byron, and a friend of Charles Babbage. -- Dave

5 years, 4 months

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EDSAC replica switched on

by Dave Horsfall

A replica of EDSAC, the Electronic Delay Storage Automatic Calculator, was switched on at Bletchley Park on this day in 2014; EDSAC was the first practical general purpose stored program electronic computer (and how's that for hair-splitting?). -- Dave

5 years, 4 months

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First permanent ARPAnet link

by Dave Horsfall

(I decided it was more suitable for COFF instead of TUHS (but sadly the membership does not overlap much.) https://en.wikipedia.org/wiki/Leonard_Kleinrock#ARPANET ``The first permanent ARPANET link was established on November 21, 1969, between the IMP at UCLA and the IMP at the Stanford Research Institute.'' And thus from little acorns... -- Dave

5 years, 4 months

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Re: [COFF] [TUHS] man-page style

by jnc＠mercury.lcs.mit.edu

> From: Grant Taylor > Thank you for the reply Sure; I love to yap about stuff like this. > I occasionally bump into some Multicians and am always pleasantly > surprised at how different their world is. Yes, it's very unlike most of what's been done since. Some of it (e.g. a strictly ordered set of rings for protection) was wrong, but there's a lot of good stuff there yet to be mined. >> Which is a pity, because when done correctly (which it was - Intel >> hired Paul Karger to architect it) Ooops, it was Roger Schell, I get them mixed up all the time. His oral history, here: https://conservancy.umn.edu/handle/11299/133439 is a Must Read. >> it's just what you > need for a truly secure system (which Multics also >> had) - but that's another long message. > If you're ever feeling bored and would like to share that story. OK, soon. > From: Bakul Shah > All of this would be easily possible on the Mill arch. if ever it gets > built. Mill has segments and protected function calls. What I found about that mostly talked about the belt stuff. Do you happen to have a pointer to the segment/call stuff? > set-uid has its own issues. Plan9 doesn't have it. Ah, what were the issues (if you happen to know)? Noel

5 years, 4 months

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Re: [COFF] [TUHS] man-page style

by jnc＠mercury.lcs.mit.edu

> From: Grant Taylor >> as an operating system person, I was, and remain, a big fan of Multics >> ... which I still think was a better long-term path for OSes (long >> discussion of why elided to keep this short). > Can I ask for the longer discussion? Sure. (Note that I'm not on COFF, so if anyone replies, please make sure I'm CC'd directly.) Basically, it boils down to 'monolithic OS's are bad' - for all the reasons laid out in the usual ukernel places (I first saw them in the BSTJ MERT paper, IIRC). {What follows is not the crispest way to explain it; sorry. I didn't feel like deleting it all and re-writing to get straight to the point, which is 'Multics had many of the advantages of a ukernel - and a long time before the ukernel idea arrived - but without the IPC overhead, which seems to be the biggest argument against ukernels'.} Now, early UNIX may have done pretty well in a _tiny_ amount of memory (I think our -11/40 V6 had about 64KB of main memory _total_, or some such ridiculous number), and to do that, maybe you have to go monolithic, but monolithic is pretty Procrustean. This was brought home to me in doing early TCP/IP work on PDP-11 Unix. The system was just not well suited to networking work - if what you wanted to do didn't fit into the UNIX model, you were screwed. Some people (e.g. BBN) did TCP as a process (after adding IPC; no IPC in UNIX, back then), but then you're talking a couple of process switches to do anything. I looked at how Dave Clark was doing it on Multics, and I was green with envy. He added, debugged and improved his code _on the running main campus system_, sharing the machine with dozens of real users! Try doing that on UNIX (although nowadays it's getting there, with loadable kernel stuff - but this was in the 70's)! To explain how this was even possible, you need to know a tiny bit about Multics. It was a 'single level store' system; process memory and files were not disjoint (as in UNIX), there were only segments (most of which were long-lived, and survived reboots); processes had huge address spaces (up to 2^18 segments), and if you needed to use one, you just mapped it into your address space, and off you went. So he wrote his code, and if I in my command process executed the 'TELNET' command, when it needed to open a TCP connection, it just mapped in his TCP code, and called TCP$open() (or whatever he named it). It fiddled around in the networking state (which was in a data segment that Dave had set up in his 'networking' process when it started up), and set things up. So it was kind of doing a subroutine call to code in another process. The security wasn't good, because Multics didn't have set-uid (so that only Dave's code would have had access to that state database) - when they later productized the code, they used Multics rings to make it secure. But still, that was pretty amazing. The key thing here is that nobody had to modify the Multics 'kernel' to support adding networking - the basic mechanisms (the single-level store, etc) were so powerful and general you could write entirely new basic things (like networking) and add them 'on the fly'. What Multics had was quite different from ukernels, but it amounted to the same thing; the system wasn't this monolithic blob, it was layered/modularized, and you could see (and gain access to, and in some cases replace - either just for yourself, or for everyone) the layers/modules. The nice thing was that to call up some subsystem to perform some service for you, you didn't have to do IPC and then a process switch - it was a _subroutine call_, in the CPU's hardware. I don't think anyone else ever tried to go down that path as a way to structure an operating system (in part because you need hardware support), and it's a pity. (UNIX, which would run on anything, killed just about _everything else_ off.) The 386-Pentium actually had support for many segments, but I gather they are in the process of deleting it in the latest machines because nobody's using it. Which is a pity, because when done correctly (which it was - Intel hired Paul Karger to architect it) it's just what you need for a truly secure system (which Multics also had) - but that's another long message. Noel

5 years, 5 months

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Happy birthday, computer mouse!

by Dave Horsfall

On this day in 1970 computer pioneer Douglas Engelbart was awarded the patent for the computer mouse. It was a fugly thing: just a squarish box with two wheels underneath it mounted at right-angles and a button. Ergonomic it wasn't... -- Dave

5 years, 5 months

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VMS epoch

by Dave Horsfall

For some reason, I have in my calendar for today: VMS Epoch http://h41379.www4.hpe.com/wizard/wiz_2315.html Epoch of the Smithsonian Astrophysical Observatory, and is Julian Day 2400000 (to allow date to fit into a 36-bit word on the IBM 704). When I visited that page, NoScript went bersek... -- Dave

5 years, 5 months

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Re: [COFF] [TUHS] man-page style

by Grant Taylor

On 11/16/2018 12:29 PM, Noel Chiappa wrote: > _That_ is what made me such a huge fan of Unix, even though as an > operating system person, I was, and remain, a big fan of Multics (maybe > the only person in the world who really likes both :-), which I still > think was a better long-term path for OSes (long discussion of why elided > to keep this short). Can I ask for the longer discussion? It sounds like an enlightening sidebar that would be good to have over a cup of COFFee. Maybe the barista on the COFF mailing list will brew you a cup to discuss this there. ~wink~wink~nudge~nudge~ -- Grant. . . . unix || die

5 years, 5 months

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In Memoriam: Jay W. Forrester, happy birthday Gene Amdahl, and LSD

by Dave Horsfall

Weird day... Computer architect Gene Amdahl was born in on this day in 1922; he had a hand in the IBM 704 and the System/360, founded Amdahl Corporation (maker of /360 clones), and devised Amdahl's Law in relation to parallel processing. But we lost Jay W. Forrester in 2016; another computer pioneer, he invented core memory (remember that, with its destructive read cycle?). Oh, and LSD was first synthesised in 1938 by Dr. Hofmann of Sandoz Labs, Switzerland; it had nothing to do with Berkeley and BSD, man... -- Dave

5 years, 5 months

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COFF November 2018