COMPONENTS OF A WINDOWS DESKTOP

2.5. CPU clock

The CPU clock synchronizes the operation of all parts of the PC and provides the basic timing signal for the CPU. Using a quartz crystal, the CPU clock breathes life into the microprocessor by feeding it a constant flow of pulses.

For example, a 200 MHz CPU receives 200 million pulses per second from the clock. A 2 GHz CPU gets two billion pulses per second. Similarly, in any communications device, a clock may be used to synchronize the data pulses between the sender and receiver.

A "real-time clock," also called the "system clock," keeps track of the time of day and makes this data available to the software. A "time-sharing clock" interrupts the CPU at regular intervals and allows the operating system to divide its time between active users and/or applications.

The Switches and Jumpers

•        DIP (Dual In-line Package) switches are small electronic switches found on the circuit board that can be turned on or off just like a normal switch. They are very small and so are usually flipped with a pointed object, such as the tip of a screwdriver, a bent paper clip, or a pen top. Take care when cleaning near DIP switches, as some solvents may destroy them. Dip switches are obsolete, and you will not find them in modern systems. 

•        Jumper pins are small protruding pins on the motherboard. A jumper cap or bridge is used to connect or short a pair of jumper pins. When the bridge is connected to any two pins via a shorting link, it completes the circuit, and a certain configuration has been achieved.

•        Jumper caps are metal bridges that close an electrical circuit. Typically, a jumper consists of a plastic plug that fits over a pair of protruding pins. Jumpers are sometimes used to configure expansion boards. By placing a jumper plug over a different set of pins, you can change a board's parameters.

NOTE: You can check the jumper pins and jumper cap at the back of an IDE hard disk and a CD/DVD ROM/Writer. More Resources

If you are on the lookout for more resources about computers, you can buy this book CompTIA A+ Certification All-in-One Exam Guide. This is a good book for those who want to know much more about computer hardware. I have used the book on numerous occasions, and Mike Meyers never disappoints.