Types of System Buses - Quick Reference

Table of Content

  1. Industry Standard Architecture (ISA)
  2. Extended Industry Standard Architecture (EISA)
  3. Micro Channel Architecture (MCA)
  4. VESA Local Bus (VESA)
  5. Peripheral Component Interconnect (PCI)
  6. PCI-X
  7. Accelerated Graphics Port (AGP)
  8. PCI Express (PCI-E, PCIe)
  9. Intelligent Input/Output (I2O)
  10. InfiniBand Architecture (IBA)

Industry Standard Architecture (ISA)

  • Introduced in 1984 with the IBM PC AT
  • 8- or 16-bit bus
  • 98-pin connector
  • 8 MB/sec bandwidth

Industry Standard Architecture (ISA) Slot

Extended Industry Standard Architecture (EISA)

  • Introducted in 1987 to compete against MCA bus
  • 32-bit bus
  • Dual purpose bus
  • Replace by better performing PCI bus

Micro Channel Architecture (MCA)

  • Developed by IBM in 1987
  • Not widely adopted by vendors as IBM charged royalties for the rights to use it
  • 116-pin connector
  • Made extinct by the license-free EISA bus and later by the PCI bus

VESA Local Bus (VESA)

  • Developed in 1992 as an extension of video memory
  • 116-pin connector
  • Replaced by better performing AGP bus

Peripheral Component Interconnect (PCI)

  • Standard bus on almost all computers of the era
  • Developed with open standards (no licensing fee to use)
  • Hot-swappable
  • Plug-and-play compatible
  • 32-bit bus
  • Can support 5 devices at a time

Peripheral Component Interconnect (PCI) Slot


  • 64-bit wide bus

Accelerated Graphics Port (AGP)

  • Introduced by Intel in 1997
  • Used mostly with AGP-compatible video cards
  • Original AGP standard (AGP 1x) offered data transfer rate of 264MB/sec
  • 32-bit wide bus
  • 132-pin connector
  • AGP 2x, 4x, and 8x offered data transfer rate of 528MB/sec, 1GB/sec,and 2GB/sec respectively
  • Replaced by PCI Express in late 2000s

PCI Express (PCI-E, PCIe)

  • Developed by Intel in 2004
  • Formerly known as 3GIO
  • 1-bit wide bus (serial communication)
  • Bandwidths:
    • PCI-E 1x: 250 MB/sec
    • PCI-E 2x: 500 MB/sec
    • PCI-E 4x: 1000 MB/sec
    • PCI-E 8x: 2000 MB/sec
    • PCI-E 16x: 4000 MB/sec
    • PCI-E 32x: 8000 MB/sec

Intelligent Input/Output (I2O)

  • Designed in 1996 by Intel and I20
  • Works along with a PCI bus
  • Uses special input and output drivers to "think for itself" thus freeing up computer resources
  • End of life in October 2000

InfiniBand Architecture (IBA)

  • Conceived in 1999
  • High-speed / high-output bus to replace PCI
  • Low latency


Very comprehensive easy format to follow.

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