Fundamentals of Computer > Central Processing Unit (CPU) > Bus System and Port Used in Microcomputer

ISA Bus (Industry Standard Architecture):

• This bus was developed by IBM (International Business Machine) for its personal computer.
• It is a 16 bit bus (At first it was 8 bit bus when developed)
• This bus is still used in many computers to attach slower devices (such as modems and input devices) to the CPU.
• It works significantly for 286 microprocessor-based computers.

EISA Bus (Enhanced Industry Standard Architecture)

• This bus is developed by a consortium of hardware developers.
• It is a 32 bit bus
• Expansion cards designed for ISA bus will run in the EISA slots. 

MCA Bus (Micro Channel Architecture)

• This bus was developed by IBM for its PS/2 microcomputer.
• It is a 32 bit bus
• Expansion cards designed for ISA bus or EISA bus do not run in the MCA bus slot.
• This bus was not backward compatible.
• It works significantly for 386 microprocessor-based computers.

PCI Bus (Peripheral Component Interconnect)

• This bus is designed by Intel Corporation
• It is a 64 bit bus
• This bus was “open domain” i.e. allowing anyone to use it without Intel’s permission or any payment to Intel.
• This bus integrates new data types, such as audio, video, and graphics.
• It is widely used in high-speed Pentium-based computers.

 

 

USB Bus (Universal Serial Bus)

• This bus is connected to the PCI bus.
• USB was at first co-invented by Ajay  Bhatt of Intel (an Indian-American computer architect) and the USB-IF (USB Implementers Forum, Inc). The organization is comprised of industry leaders like Intel, Microsoft,  Compaq, LSI, Apple and Hewlett-Packard.
• Unlike the PCI bus, USB is a hot swappable bus. (Hot Swappable means, a user can connect and then disconnect a USB device without affecting the machine.
• It allows connecting lower speed I/O devices to PC such as mouse, keyboard, flash memory, etc. without having to go through a complex installation procedure.
• USB supports up to 127 devices connected in either a daisy chain or hub layout.

PCMCIA Bus

• This bus was developed by the Personal Computer Memory Card International Association (PCMCIA).
• It is a 32 bit bus.
• It allows user to insert credit card-size peripherals such as memory cards, modems etc.
• It is an open domain (i.e. allowing anyone to use it without permission), nonproprietary bus standard.
• This bus is used for notebook, sub-notebook and palmtop computers.
• A card used in this bus is now called PC Card.

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Types of Bus and Their Role

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Standard and Specialized Expansion Ports

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