What are the common bus architectures and their characteristics?

The most popular expansion bus designs are distinguished as follows:

• PCI - Peripheral Connection Interface. Currently the most popular and fastest bus design. PCI was developed by Intel and has essentially become the industry standard for Pentium systems. It can exchange data with the CPU at 32- or 64-bits per second and supports bus mastering (allows �intelligent� cards to do processing independent of the CPU). It also supports multiplexing (the sharing or �mixing� of signals on the bus). PCI slots only accept PCI cards and PCI cards only fit in PCI slots.
• VLB - VESA (Video Electronics Standards Association) Local Bus. VLB was originally designed to remove the display adapter as the system bottleneck. Supports 3 slots for high speed peripherals on what is essentially the 32-bit local bus (CPU). It also supports bus mastering and offers backward compatibility (i.e., a VLB slot will accept an ISA card but the ISA card still functions as an ISA card; it does not access the local bus.).
• MCA - Micro Channel Architecture. Developed by IBM for its PS/2 computers, this design never really caught on. Data path is 16- or 32-bits wide. An MCA slot accepts only a MCA card.
• EISA - Extended Industry Standard Architecture. A counter to IBM�s MCA design that transfers data at 32-bits and offers backward compatibility (i.e., EISA slot will accept ISA card). EISA never really caught on except in some specialized servers.
• ISA - Industry Standard Architecture. The original bus design. Also known as the PC/AT bus. Data is transferred at either 8-bits or 16-bits depending on the card. A 16-bit ISA slot will accept an 8-bit ISA card or a VLB card.