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					A+ Essentials

Lesson 11


Learn about expansion cards, electrical system and motherboard configuration settings

Mini Lesson

Expansion (interface) cards

Circuit boards other than the motherboard inside the computer are called expansion cards or
interface cards. They are mounted on expansion slots.

The Electrical system

The most important component of the computer’s electrical system is the power supply. The
power supply converts and reduces the electricity to a voltage that the computer can handle. The
power supply receives 110-120 volts of AC from the wall outlet and converts it to much lower
DC voltage. New power supplies provide 3.3, 5 and 12 volts DC.

Instruction stored on the motherboard

Some very basic instructions are stored on the motherboard, just enough to start the computer,
devices such as floppy disk, hard drive, keyboard and search for operating system. These
instructions are stored in ROM chips and are called BIOS (Basic Input Output System). These
instructions are permanently etched into it during fabrication. It is not easy to change them.
Software embedded into the hardware is called Firmware. New ROM chips on motherboards
can be programmed. These are called Flash ROM.

Plug and Play

Plug and Play (PnP) is a feature of BIOS and operating system to make installation of new
hardware easier. If the BIOS is PnP, it will begin the process of configuring hardware devices
and pass the information to the OS. Os will use the information and complete the configuration.

Motherboard configuration settings

Another component on the motherboard, called CMOS configuration chip, contains small
amount of memory to hold setup information about the computer. This chip is responsible for
remembering current date, time, which hard drive and floppy drives are present, how serial and
parallel ports are configured, etc.

A motherboard can also retain setup information in different settings of Jumpers. A jumper is
considered open or closed based on whether a jumper cover is present on two small posts or
metal pins. A DIP (Dual Inline Package) switch is similar to a light switch and is on or off for
various settings.

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