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Input/Output Organization III: Commercial Bus Standards

Input/Output Organization III: Commercial Bus Standards. CE 140 A1/A2 20 August 2003. Bus. Pathways of interconnections between different computer components Three general types; data, address, control. Bus characteristics. Bus width – how many bits can be transmitted at a time

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Input/Output Organization III: Commercial Bus Standards

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  1. Input/Output Organization III: Commercial Bus Standards CE 140 A1/A2 20 August 2003

  2. Bus • Pathways of interconnections between different computer components • Three general types; data, address, control

  3. Bus characteristics • Bus width – how many bits can be transmitted at a time • Bus speed – how many bits can be transmitted across each wire per second • Bus bandwidth – bus width x bus speed (same as maximum throughput)

  4. IBM PC/XT Bus • Used on 8088-based systems • 8-bit bus • Copied by clone vendors for compatibility with third-party I/O boards

  5. IBM PC/XT Bus Source: Phil Storrs PC Hardware book <http://members.iweb.net.au/~pstorr/pcbook/showtell/show2.htm>

  6. IBM PC/AT Bus • Used on the 80286-based PC/AT • Maintained compatibility with the XT bus • Added an edge connector to increase bus width to 16-bits

  7. ISA • Industry Standard Architecture • Same as the PC/AT Bus • 16-bit, 8.33 MHz  Maximum throughput 16.7 MB/s • Limited bus master support

  8. ISA Source: <http://www.rackmountnet.com/ipc/isa_bk/isa_bk.htm>

  9. Problems with ISA • Slow • Limited number of interrupts • Lack of bus master support • Specific to Intel architecture  cards built using ISA will not work on non-Intel platforms • IBM-specific problem: no more monopoly on the hardware market

  10. MCA (IBM’s response) • MicroChannel Architecture • Developed by IBM for the PS/2 line • 16-bit/32-bit computer bus • 10-16 MHz • Intended to replace the ISA bus • Allows bus mastering • Limited plug and play • Limited to IBM hardware • Incompatible with XT, ISA boards

  11. EISA (Industry’s response) • Extended Industry Standard Architecture • Extends ISA bus to 32 bits • Maximum throughput: 33.3 MB/s • Increased bus mastering support • Maintains compatibility with old ISA boards

  12. EISA Source: <http://www.atmarkit.co.jp/fpc/slotsocket/indexpage/>

  13. Need for a faster bus • Original IBM PC: text-based applications • Advent of GUIs (Windows, et al) demand high performance

  14. Need for a faster bus • Example • 1024 x 768 display • 24-bit color • 30 frames per second •  67.5 MiB/s • ISA: 16.7 MB/s • EISA: 33.3 MB/s

  15. Local Bus Concept • Demand for higher bandwidth and increased throughput • Bus placed near (or on) the processor’s memory bus • “Local” to the processor • Does not have to go through the slower ISA bus

  16. VESA Local Bus • Developed by Video Electronics Standards Association (VESA) • High-speed conduit for memory-mapped I/O and DMA • Intended for high-bandwidth peripherals (video, storage, etc.) • 33 MHz, 32-bit • Extension of the 486 memory bus

  17. VESA Local Bus Source: <http://www.lco-college.edu/classes/pc-ware/chap4b.html>

  18. PCI • Peripheral Component Interconnect (PCI) • Developed by Intel (90’s) but standard was made public  platform independent • 33 Mhz, 32-bit  Maximum throughput 132 MB/s • Plug-and-Play

  19. PCI Source: <http://www.ontrack.com/hardwareinfo/input-output.asp>

  20. PCI Variants • PCI 2.2: 64-bit, 66 Mhz  Maximum throughput: 533 MB/s • PCI-X: 64-bit, 133 Mhz  1066 MB/s • PCI-X 266 (PCI-X DDR)  2133 MB/s • PCI-X 533  4 GB/s • Mini PCI – small form factor PCI cards for use with embedded systems/portable systems

  21. Problem with using PCI alone • Still not fast enough for memory • Not compatible with ISA cards

  22. Intel’s Solution: Northbridge/Southbridge Architecture • Uses bridge chips • PCI Bridge (Northbridge) • Connects CPU, memory, and PCI bus • ISA Bridge (Southbridge) • Connects PCI bus to the ISA BUS and also supports one or two ATA disks • Advantage: • High-bandwidth memory bus (Front Side Bus) • PCI bus available for high-bandwidth peripherals • Next generation: Intel Hub Architecture

  23. Northbridge/Southbridge Architecture Source: Structured Computer Organization by Tanenbaum

  24. AGP • Accelerated Graphics Port • High-speed computer bus designed for 3D computer graphics acceleration • AGP 1X: 32-bit, 66 MHz • Also available: 2X, 4X, 8X

  25. AGP Source: http://www.watch.impress.co.jp/pc/docs/article/991008/hotrev30.htm

  26. PCI-Express • Next generation PCI implementation from Intel • Intended to replace AGP and PCI altogether • Not fast enough as a memory bus • Alternatives: HyperTransport

  27. SCSI • Small Computer Systems Interface • Pronounced “scuzzy” • Higher transfer rate than ATA disks • Used in workstations and servers • More than just a hard disk interface, a full-fledged bus • Also supports CD-ROMs, CD-recorders, scanners, tape units, etc. • Devices are daisy-chained in a linear manner • Terminated at the end to prevent reflection

  28. SCSI Types

  29. SCSI • Typical 8-bit SCSI cable • 50 wires, 25 ground, 8 for data, 1 for parity, 9 for control

  30. IEEE 1394 • Developed primarily by Apple • Commonly referred to as Firewire (Apple), i.Link (Sony) or digital video (DV) port • Used for data storage devices and digital video cameras • Does not require a host • IEEE 1394a: up to 400 Mbps • IEEE 1394b: up to 800 Mbps • Allows daisy-chaining, plug-and-play, and hot-swapping

  31. USB • Universal Serial Bus • Developed as a replacement to the serial and parallel ports • USB 1.1 – Up to 12 Mbps • USB 2.0 – Up to 480 Mbps • Up to 127 devices (THEORETICAL!) • Daisy-chained in a tree structure • Requires a host computer • Upcoming: USB On the Go

  32. Storage Interfaces • ATA • Serial ATA • SCSI • IEEE 1394 • USB

  33. ATA • Advanced Technology Attachment • Standard interface for connecting storage devices • Transitioned from PIO to DMA modes • With the advent of Serial ATA, it has been retroactively renamed Parallel ATA

  34. ATA Types • Most new drives support Ultra DMA Modes (in contrast to Programmed I/O modes) • Ultra ATA/33 – 33 MBps • Ultra ATA/66 – 66 MBps • Ultra ATA/100 – 100 MBps • Ultra ATA/133 – 133 MBps

  35. ATA-VI • Supports 48-bit addressing that allows system to address 144 PB • Breaks the 137 GB size barrier imposed by older ATA standard

  36. ATA Cables

  37. Serial ATA • Higher speed than Parallel ATA • Hot-swappable • Cable: 7-wire cable versus 40/80-wire cable • Power cable: 15 pins • Initial speed: 150 MBps • Later implementations: 300 MBps, 600 MBps

  38. Serial ATA Cables

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