Computer Architecture CST 250 BUS EXPANSION CARDS ARCHITECTURE

Computer Architecture CST 250 BUS & EXPANSION CARDS ARCHITECTURE Prepared by: Omar Hirzallah

Contents l BUS Architecture ¡Data Bus ¡Address Bus ¡Control Bus l Expansion Cards ¡PCI, MCA, ISA ¡EISA, VESA, AGP

BUS ARCHITECTURE Address Bus PROCESSOR Data Bus Control Bus Input / Output MEMORY

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. Processor Types and Associated Data Bus Widths Processor Data Bus Width 8086 AND 80286 16 bits (2 Bytes) 80386 AND 80486 32 bits (4 Bytes) Pentium, Pentium Pro, PII, PIII, PIV, PIIXEON, PIII-XEON 64 bits (8 Bytes) 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 Processor Address Lines Addressable Memory 8086 20 bits 1 MB 80286 24 bits 16 MB 80386, 80486 & Pentium Pro, P II, IV, PII-xeon & PIII-xeon 32 bits 4 GB 36 bits 64 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 / Read IRQ ----- Interrupt Request EXPANSION CARDS: Type Full Form ISA Speed Arch. Industry Standard Architecture 8 MHz 16 bits MCA Micro Channel Architecture 10 MHz 32 bits EISA Extended Industry Standard Architecture 8 MHz 32 bits Peripheral Component Interconnect VESA Video Electronics Standards Association 33 MHz 64 bits 33 MHz 32 bits PCI

Expansion cards l PCI: Peripheral component interconnect. ¡ 32 bit bus card. ¡Runs at 33 Mhz ¡It has connectors similar to those on MCA and EISA cards. ¡PCI slot will not accept ISA or 8 bit cards. ¡Supports Pn. P ( plug and play) l PCI Express: l MCA: Micro channel ¡Developed by IBM. ¡Include circuit which looks like Pn. P. l ISA: Industry Standard Architecture. ¡ 16 bit data lines. ¡Speed 8 MHz ¡Doesn’t support Pn. P.

Expansion cards l EISA: Extended Industry Standard ¡Compatible with ISA. ¡ 32 bit data line. ¡Supports Pn. P. ¡Performance is low. l VESA: Video Electronic standard Association ¡ 32 data line. ¡Speed of 33 MHz. ¡Designed to work with Intel 486 processor and not with Pentium. ¡Doesn’t support Pn. P. l AGP: Accelerated Graphics port. ¡It is designed for graphics communication.