Contents BUS Architecture Data Bus Address Bus Control Bus Expansion Cards PCI, MCA, ISA EISA, VESA, AGP
BUS ARCHITECTURE PROCESSOR MEMORY Input / Output Address Bus Data Bus Control Bus
DATA BUS: The data bus is used to move the data between the various components (e.g. CPU, Memory, Input & Output Devices) in the system. ProcessorData Bus Width 8086 AND 8028616 bits (2 Bytes) 80386 AND 8048632 bits (4 Bytes) Pentium, Pentium Pro, PI, PII, PIII, PIV, PII- XEON, PIII-XEON 64 bits (8 Bytes) Processor Types and Associated Data Bus Widths Size of 1 Read Operations
ADDRESS BUS: The CPU uses it to send the Physical addresses of computer memory to different units of computer. CPU also use it to locate memory or I/O devices. The width of The address determines the maximum size of memory. Processor Types and Associated Address Bus Widths ProcessorAddress Lines Addressable Memory 808620 bits1 MB 8028624 bits16 MB 80386, 80486 & Pentium 32 bits4 GB Pentium Pro, P II, III, IV, PII-xeon & PIII-xeon 36 bits64 GB
CONTROL BUS: It is used to carry control signals from the processor to other components of the system. Here are some examples of control signal notations generated by processor. W/R ----- Write / ReadIRQ ----- Interrupt Request TypeFull FormSpeedArch. ISAIndustry Standard Architecture8 MHz16 bits MCAMicro Channel Architecture10 MHz32 bits EISAExtended Industry Standard Architecture 8 MHz32 bits PCIPeripheral Component Interconnect 33 MHz64 bits VESAVideo Electronics Standards Association 33 MHz32 bits EXPANSION CARDS:
Expansion cards PCI: Peripheral component interconnect. 32 bit bus card. Runs at 33Mhz It has connectors similar to those on MCA and EISA cards. PCI slot will not accept ISA or 8 bit cards. Supports PnP ( plug and play) PCI Express: MCA: Micro channel Developed by IBM. Include circuit which looks like PnP. ISA: Industry Standard Architecture. 16 bit data lines. Speed 8 MHz Doesnt support PnP.
Expansion cards EISA: Extended Industry Standard Compatible with ISA. 32 bit data line. Supports PnP. Performance is low. VESA: Video Electronic standard Association 32 data line. Speed of 33 MHz. Designed to work with Intel 486 processor and not with Pentium. Doesnt support PnP. AGP: Accelerated Graphics port. It is designed for graphics communication.