Path: utzoo!attcan!utgpu!news-server.csri.toronto.edu!clyde.concordia.ca!uunet!mcsun!ukc!dcl-cs!aber-cs!athene!pcg From: pcg@cs.aber.ac.uk (Piercarlo Grandi) Newsgroups: comp.arch Subject: Re: Historical architectural advances?? Message-ID: Date: 13 Oct 90 10:14:40 GMT References: <1990Oct4.001346.4139@Stardent.COM> <8052@scolex.sco.COM> <2926@sequent.cs.qmw.ac.uk> <1990Oct11.164904.12550@zoo.toronto.edu> Sender: pcg@aber-cs.UUCP Organization: Coleg Prifysgol Cymru Lines: 80 Nntp-Posting-Host: odin In-reply-to: henry@zoo.toronto.edu's message of 11 Oct 90 16:49:04 GMT On 11 Oct 90 16:49:04 GMT, henry@zoo.toronto.edu (Henry Spencer) said: henry> In article <2926@sequent.cs.qmw.ac.uk> eliot@cs.qmw.ac.uk (Eliot henry> Miranda) writes: eliot> I think you have to include the Xerox Alto (ancestor of the Xerox eliot> D machines). It was the first personal computer with all of the eliot> following eliot> ... eliot> interface to ethernet eliot> multitasking microprogramming (8 different microcode eliot> tasks at different priorities) henry> These last two are kind of cheating. The Alto was the first machine of henry> any kind with an Ethernet interface, since Ethernet was invented as a henry> fast communication system for the Alto. This is not cheating -- it is a real first, IMNHO, as far as Ethernet is concerned. But then I would also put the Cambridge ring system in as an important historical first (as a processor pool system). henry> I suspect that if you dig for it, you could find earlier machines henry> with fast communications links. Yes, the MU5 multicomputer complex. Well, among the machines that made the history of architecture I would put every architecture from Manchester University; the most recent ones have been the MU5 (late sixties, early seventies) that among many other things was the first heterogenous multicomputer complex with a portable network operating system I can think of (the os was much, much faster and more powerful than 4BSD networking, and 10-15 years before it, and around one tenth the size), where the 'local net' was a giant OR-gate, the MU6, which, among other things, as far as I know was the first 64 bit supermini (late seventies, early eighties), and the Dataflow Machine (first operational general purpose dataflow architecture to run real programs, and for a long time the only one that actually worked, from what I remeber). Not to mention the previous generations, like Atlas (MU4?), the first virtual memory machine (and much else besides) etc... Naturally the problem is that only 'in' people know much about the Manchester University work. This is amazing, because I know of no other group (except perhaps for Zuse's group) that has had an unbroken record of developing 6 successive generations of state of the art supercomputer architectures over forty years. Many commercial companies have done it, of course, but without the continuity (a doubt here: maybe Burroughs) of the architecture group. Even Seymour Cray is a relative newcomer compared to them. henry> And the multimicroprogramming is a dubious "first", since almost henry> nobody has copied it; it qualifies as peculiar rather than henry> history-making. Didn't the Burroughs minis have multimicroprogramming as standard long before the Alto? From what I remember the 1700 had statically loaded multi microprograms, while the 1800 even had *paged* microcode... Note that the Burroughs concept was not bad -- they achieved phenomenal code densities. They had a separate microprogram for each language, so to run multiple language in multiprogramming you had to be able to switch microcode (and instruction set) at every context switch. Phenomenal code densities are also a property of the Burroughs mainframe architecture, incidentally -- if only they had multiple arithmetic stacks they would have been fast on numeric problems too. The instruction sets were tailored to each compiler, and each compiler could thus make easy use of the complex instructions, thus removing one of the major problems of CISC architectures, that complex instruction almost never match what the compiler wants to do, and thus are rarely used. Note: phenomenal code densities means up to a a fifth/tenth of VAX/68000/386 code size. -- Piercarlo "Peter" Grandi | ARPA: pcg%uk.ac.aber.cs@nsfnet-relay.ac.uk Dept of CS, UCW Aberystwyth | UUCP: ...!mcsun!ukc!aber-cs!pcg Penglais, Aberystwyth SY23 3BZ, UK | INET: pcg@cs.aber.ac.uk