PCI Buses

• Peripheral Component Interconnect Interface

Typical PCI Card

• Most PCs have two sets of buses – System bus or local bus

• Connects the microprocessor with the system memory

– Other buses (ISA, PCI, etc…)• Connect to the system bus via a bridge

– Bridge integrates the data from the bus with the data from the system bus

Dual Independent Buses

                                                     

                                                                 

Buses

• Backside Bus – Provides a fast direct channel between CPU

and Level 2 Cache

• Frontside Bus– Connected to Memory via a memory controller– Connected to CPU– Connected to other buses via a bridge

Another Main Bus

• Shared Bus– Allows many peripherals connected to it to

connect to CPU and memory• Modems• Hard Drive• Sound Card• Graphics Card• Controller Card• Scanner

Bus History

• Original Bus – 8-bits wide– Operated at 4.77MHz

• ISA (Industry Standard Architecture – 1982)– 16 bits wide– 8MHz

• EISA (Extended ISA)– 32 bits wide– 8 MHz

• VL –Bus (VESA Local Bus)– 32 bits wide– Operated at processor speed

PCI Uses 47 Pins

Bus Type Bus Width Bus Speed MB/sec

ISA 16 bits 8 MHz 16 MBps

EISA 32 bits 8 MHz 32 MBps

VL-bus 32 bits 25 MHz 100 MBps

VL-bus 32 bits 33 MHz 132 MBps

PCI 32 bits 33 MHz 132 MBps

PCI 64 bits 33 MHz 264 MBps

PCI 64 bits 66 MHz 512 MBps

PCI 64 bits 133 MHz 1 GBps