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Unix System Administration

This article explores the evolution of computer bus architectures, including ISA, EISA, PCI, and SBUS, along with their technical specifications and historical significance. It investigates the ISA bus's origins, EISA's emergence as an alternative, the rapid development of PCI, and the related concepts of bus mastering and plug-and-play technology. This detailed account also covers important memory types, data transfer rates, and their impact on early computer hardware, providing a foundational understanding for both enthusiasts and professionals in the field.

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Unix System Administration

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  1. Unix System Administration Computer Hardware

  2. ISA Jar Jar Binks, ISA Annoying • Industry Standard Architecture • Original PC Bus • 8-bit ISA (1980) • 8.3MHz bus speed • 7.0 Mbytes per second • 16-bit ISA • 8.3MHz bus speed • 15.9 Mbytes per second

  3. Microchannel? Narrow Urethra? • “IBM proprietary” bus meant to extend the ISA bus • Primarily used in PS/2 and RS/6000 computers • 8, 16, 32-bit transfers • Introduced concept of “bus mastering” and “plug and play” • Not widely implemented and was rivaled by the EISA bus architecture

  4. EISA, Wanna Buy a Vowel? • Originated in 1988 & 1989 by the “Gang of Nine” - AST, Compaq, Epson, HP, NEC, Olivetti, Tandy, Wyse & Zenith • Designed as alternative to microchannel • EISA connectors are a superset of ISA, so both EISA and ISA card will work in the same slot • Bus mastering, shared interrupts • 32-bits, 8.3MHz, 31.8 Mbytes/sec

  5. Take the SBUS Downtown • Developed by Sun for its new SPARCstation systems in 1989 • Existing ISA and EISA weren’t powerful enough • Today, Sun is moving to the PCI Bus • However, SBUS I/O throughput is often 30-50% faster than PCI implementations • Over 3 million SBUS slots are in use today • SBUS is an IEEE standard

  6. VLB - Very Large Band-aid? • VESA Local Bus • Created to help solve the need for large video transfers created by emerging graphical applications (e.g. Windows) • Separate faster bus to augment the ISA bus. • VL bus put on processors faster memory bus, or “local” to the processor. • VL slots accept both VL & ISA cards • 32-bit, 33MHz, 127.2 Mbytes/sec

  7. PCI - Backwards, I C P • Successor to VLB, EISA, Microchannel and SBUS • Tends to co-exist with ISA still today • Supports, bus mastering, shared interrupts, plug-n-play • PCI - 32-bits, 33MHz, 127.2 Mbytes/sec • PCI 2.1-64-bits, 66MHz, 508.6 Mbytes/sec • New 100MHz bus support too!

  8. Plug ‘n Pray • Plug-n-Play was designed to make it easier for to install PC cards • Macs and Suns had a type of play-n-play from their inception • Eliminated the need to set dip switches or jumpers on the expansion card • ISA cards were retrofitted with a type of plug-n-play

  9. Interface cards: SBUS, ISA (16), PCI (32), MCA(16), EISA

  10. Let’s Get Graphic! • AGP - Accelerated Graphics Port • 32-bits wide (same as PCI) • Runs at full bus speed of 66MHz (PCI runs at 1/2 bus speed). • Minimum of 254.3 Mbytes/sec • 2X and 4X mode for faster data transfer • 4X = 1,017MB/sec, but theoretical 100MHz bus limit is 763MB/sec.

  11. That’s UPA, not UPE • UPA - Ultra Port Architecture • Peak rate of 1.3GBytes/sec • Packet switching instead of a bus • Unlimited number of buses per system • Can tie together other, commodity buses such as PCI • Example: Sun Ultra Enterprise 450 has 6 PCI buses managed by a UPA

  12. 1+1 Does Not Always Equal 2 • Calculating bandwidth • ( bit-width/8 ) * ( bus-speed ) * (1,000,000/1,048,576 ) = MBytes/second • ( 32 bits / 8) * (33.3MHz) * (1,000,000/1,048,576) = 127.2 Mbytes/second • “M” in MHz = 1,000,000 (10^6) • “M” in Mbytes = 1,048,576 (2^20)

  13. I Seemed to Have Lost Some Memories. Oh, There They Are.

  14. What Was I Talking About? Oh Yeah, Memory. • DRAM - centipede memory chips • SIMM - • 30 pin, 72 pin • ECC, EDO, FPM • DIMM • 168 pin • SDRAM, PC100 • RDRAM • 184 pin RIMM • 600-800MHz

  15. Can You Factor the Form • AT, Baby-AT • ATX, mini-ATX • LPX, mini-LPX, NLX

  16. Have you hard the one about… • Hard drive technology • MFM - Modified FM • RLL - Run Length Limited • ESDI - Enhanced Small Device Interface • SCSI - Small Computer • IDE - Integrated Drive Electronics

  17. Muth Freakin Monster • Modified Frequency Modulation • Early drive type - more “compact” encoding scheme than FM (reduced redundant cycles by considering previous bit encoding) • Appx 2X capacity of FM • Used on floppies - “double density” • Drives had no processing electronics onboard

  18. Requires Lotsa Luck • Run Length Limited • Modified encoding scheme again, associating flux patterns with bit sequences - appx 30% increase over MFM • Family of techniques: • PRML - permits weaker field strengths for higher areal density [track-to-track and linear] - flux reversals harder to detect - use DSP (30-40% increase in density) • EPRML - even higher densies (linerarly) using enhanced DSP - 20 to 70% increase (THIS IS USED TODAY)

  19. Extra Stupid Development Initiative? • Enhanced Small Device Interface • Attempt to improve MFM/RLL interfaces • Short-lived due to SCSI/IDE release

  20. Itsa Device Explosion!! • Integrated Drive Electronics - drive unit contains all interface electronics required. Attaches directly to system bus • Two devices per channel, two channels per system, device communication monopolizes the channel, length limits on cable • High system resource requirements due to direct interaction with system bus

  21. Who you callin SCSI? • Small Computer System Interface • Supports higher device counts and longer cable lengths • Performance high for large numbers of devices • Permits command queuing and reordering • Separate bus and controller, offloads management and transfer functions from CPU • High cost • All devices can be targets or initiators (yes, even the PC)

  22. You Are Elle’s • Hardware Specs • http://www.techfest.com/hardware/http://www.pcguide.com/ • Sun UPA Spec • http://www.sun.com/microelectronics/whitepapers/wp95-023.html

  23. Wake Up! • What does PCI stand for? • What cards other than graphics cards fit in the AGP slot? • Why would Sun switch to PCI bus if SBUS can attain 30-50% better I/O throughput?

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