Data Bus Width
Modern Pentium class motherboards have a data bus with 64 bits . That is the width of the data highway that goes in and out of the processor. The Pentium processors, however, do use 32-bit registers to handle 32-bit instructions.

Bus speeds and widths have increased due to faster processors and the needs of multimedia applications. Typical bus names and widths are:

• Industry Standard Architecture (ISA) - 8 or 16 bits
• Extended Industry Standard Architecture (EISA) - 8 or16 bits
• Microchannel Architecture (MCA) - 16 or 32 bits
• VESA Local Bus (VLB) - 32 bits
• Peripheral Component Interconnect (PCI) - 32 or 64 bits
• Accelerated Graphics Port (AGP ) - 32 bits