Time: Sat Sep 20 12:39:58 1997 by primenet.com (8.8.5/8.8.5) with ESMTP id MAA23335 for [address in tool bar]; Sat, 20 Sep 1997 12:39:30 -0700 (MST) Date: Sat, 20 Sep 1997 12:37:45 -0700 To: Reed Harris <rharris@mail.telis.org> From: Paul Andrew Mitchell [address in toolbar] Subject: short hardware tutorial Cc: <Cheryl.Miola@digital.com> Cheryl, Your stuff is near the end of this message (see infra). /s/ Paul Mitchell http://supremelaw.com Reed et al., Browse around this website, and keep looking for the list of disk drives. At the very end of the "Hard Drive Lots," they have a Quantum Bigfoot 6.5GB EIDE, and a Seagate 9GB Fast SCSI. It might be worthwhile to monitor these auctions, and place a competitive bid just before closing. The current high bidders are running at <50% of retail prices; this means you can buy hard disks for about 5 cents per megabyte now! Read that again!! As for EIDE drives, don't get into anything less than the Ultra-DMA drives, which are running at 33MB/sec transfer rate. All older EIDE drives have a 16.6MB/sec transfer rate -- (not so) obviously inferior for a Pentium-class machine with 32-64MB of RAM, lots of peripherals, and a clock speed of 200MHz or more. Just do the numbers: the clock speed is a rough measure of the bit stream rate in, or out, of the CPU. One hundred megaHertz (100Mbits/sec) at 8 bits per byte is 12.5 MB/sec; thus, two hundred megaHertz is 25 MB/sec (+/-). Clearly, the slower EIDE drives cannot keep up with the dominant class of Pentiums now being shipped. ASCII is actually a 7-bit code, but bit 8 always trails along, because hardware channels are built on multiples of two (digital/binary arithmetic). 9-track tapes reserved 8 bits for data, and 1 bit for error checking. I went with Ultra-DMA 5.1GB EIDE drives from Western Digital, because their current cost was easily 50% less, per megabyte, than a comparable SCSI-II drive. For future expansion, and as a hedge on future changes in these relative prices, I also ordered a dual-ported ADAPTEC SCSI-II controller, which can handle 30 different peripherals (2 x (16 - 1)). SCSI-II has a hardware address space for 16 devices, one of which must be assigned to the controller itself. So, each SCSI controller can support up to 15 peripherals (CD-ROM drives, hard disks, scanners, etc.); a dual-ported SCSI controller can handle twice this, or 2 x 15 = 30 devices. Adaptec has one of THE best dual-ported controllers on the market. SCSI stands for "Small Computer Systems Interface"; it was a standard developed for large minicomputers, now scaled downwards in size, due to the onward rush to still more miniaturization. It is a very stable technology, particularly when coupled with fast PCI motherboards ("Peripheral Component Interconnect"). PCI boards have several "regions", one of which supports slots for old ISA cards, with a "bridge" chip which moves data from these slower cards, onto the faster native bus. This PCI architecture was the brainchild of Intel. Peter Norton has a great description in one of his PC bibles, which I have in my book library. Now, the really good news is here: The technology to keep your eyes on, is the Alpha chip from Digital Equipment Corporation. They are now in production with a 500MHz chip, which was just upgraded to a 600MHz model (the top of the line). They are fast approaching the gigaHertz threshold, and I believe that they will be the first to break through (!), despite Intel's obvious leadership in the mainstream. So, keep your eyes on DEC; I believe theirs will be one of THE dominant technologies of the near future (e.g. 128-bit internal channels). This is a RISC design, which makes the engineering a whole lot easier to cycle through multiple generations. E.g., Hewlett Packard recognized the advantages of RISC many years ago. A commercial-grade GigaHertz (GHz) chip will, quite obviously, be a GigaNTic milestone in the history of contemporary computing. Do the numbers again: one gigahertz at 8 bits per byte is 5 x 25 = 125MB/sec transfer rate (+/-). That is, such a speed could FILL a 100 megabyte hard disk in less than one second of real time!! Pretty exciting, I say!!! /s/ Paul Mitchell http://supremelaw.com copy: off-site archivists, Digital Equipment Corp. Dear Clients, Super deals on surplus computer equipment are available at URL: http://www.surplusauction.com There's a real-time auction going on all the time. Check it out! It's fun!! /s/ Paul Mitchell http://supremelaw.com ======================================================================== Paul Andrew Mitchell, Sui Juris : Counselor at Law, federal witness B.A., Political Science, UCLA; M.S., Public Administration, U.C. Irvine : tel: (520) 320-1514: machine; fax: (520) 320-1256: 24-hour/day-night email: [address in toolbar] : using Eudora Pro 3.0.3 on 586 CPU website: http://supremelaw.com : visit the Supreme Law Library now ship to: c/o 2509 N. Campbell, #1776 : this is free speech, at its best Tucson, Arizona state : state zone, not the federal zone Postal Zone 85719/tdc : USPS delays first class w/o this _____________________________________: As agents of the Most High, we came here to establish justice. We shall not leave, until our mission is accomplished and justice reigns eternal. ======================================================================== [This text formatted on-screen in Courier 11, non-proportional spacing.]
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