Types of System Buses - Quick Reference

Industry Standard Architecture (ISA)

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)

PCI-X

• 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