Xref: utzoo alt.folklore.computers:7579 comp.unix.internals:1180 comp.misc:10684 Path: utzoo!attcan!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!wuarchive!mit-eddie!rs From: rs@eddie.mit.edu (Robert E. Seastrom) Newsgroups: alt.folklore.computers,comp.unix.internals,comp.misc Subject: Hardware Architectures and I/O (was: Re: Jargon file...) **FLAME!!** Message-ID: <1990Dec2.154303.17105@eddie.mit.edu> Date: 2 Dec 90 15:43:03 GMT References: <1YbxGQ#2fbT353y6xKD8DT83C4bFDpV=eric@snark.thyrsus.com> <1990Nov30.172512.5282@sctc.com> Reply-To: rs@eddie.MIT.EDU (Robert E. Seastrom) Organization: MIT EE/CS Computer Facilities, Cambridge, MA Lines: 52 In article pst@ir.Stanford.EDU (Paul Traina) writes: > >Back when there were REAL(tm) computers like 780, a lot of time and >energy went into designing efficient I/O from the CPU bus to the >electrons going to the disk or tty. > Damn right, but even the 780 was a step down. Get your KL-10 documentation set out and read about *them*. Front-end PDP-11s that did Tops-20's command completion. Seperate I/O and memory buses. 8-ported (that's eight, son) memory that talked to the I/O front-end machines for *real* DMA, not cycle stealing! >Sure OS's and apps have gotten bloated, but when you put a chip like >the MIPS R3000 on a machine barely more advanced than an IBM-AT you >end up with a toy that can think fast but can't do anything. I can't >really blame companies like DEC and Sun for producing mismatched >hardware, because their marketing drones are constantly trying to >undercut each other in price. It's a hell of a lot more expensive to >ship a product with a well designed I/O system than to drop in a >"killer bitchen" CPU chip; occasionally someone makes the attempt do >design a great piece of hardware, and you end up with something not >half bad (like the DECstation 5000, which is only crippled by Ultrix You left out the worst offender of them all - IBM. The RS-6000 may crank out 27 MIPS, but it can't context switch or handle interrupts worth shit. You can lower machine performance to the point of unusability by FTPing a file from another machine on the same ethernet segment! Next time get a chance to play with an RS-6000, try this: Pop about a dozen xterms, iconify them, put the icons in a row, and wave the pointer back and forth over them as fast as you can. Astounding, no? The highlighting on the icons will keep bouncing back and forth long after you stop waving the pointer. My personal record is 20 seconds. Makes a Sun-2 running display Postscript seem astoundingly fast. RS-6000s also have an annoying tendency to "lock up" for a few seconds (5 < x < 15) and then return to normal - I'm told that this is normal and due to paging activity. The microchannel card cage design is pretty bad too - sure, you can put cards in, but God help you if you have to take them back out! And you better tighten down the retaining screws all the way... or the first time you look at the card funny it will pop out. To its credit, I must say it compiles GNU Emacs faster than any other machine I've used, but I do more with a workstation than just run compiles. And, if you think Ultrix is bad, it's only because you haven't tried AIX. ---Rob -- Internet: rs@eddie.mit.edu | Copyright: Protecting your right to Bitnet: RS@SESTAK | copy software. X.25: PSI%0240200101905::KICKI::RS | ---gumby@cygnus.com Brought to you by Super Global Mega Corp .com