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What is a Computer?

Computers - Desktop

What is a computer?

Most computers today are classified as either a desktop computer or a laptop. A desktop computer is typically less expensive for the same performance and features and typically comes with a better monitor, higher performance, and more features than a laptop. The laptop has the distinct advantage in being portable and running off of batteries.

From the outside the typical desktop computer is made up of a few major components:

What is in that big computer box?

The main computer box is where most of the computer intelligence is contained.

The motherboard: The motherboard is the main card in the box. It typically has the main CPU, Chipset, RAM, connections to the hard disk drives, PCI slots, connections to the power supplies, and some other peripheral connections like USB and Ethernet.

Power supply: The PCs power supply is usually a metal box that has an AC outlet to plug into the wall and then some wired cables to connect to the motherboard as well as to the hard disk drives and CD/DVD ROM drives.

Hard disk drive (HDD): This is where all the computer's software is stored. Hard disk drives are "static" memory, meaning that the memory remains intact even when the power is turned off.

CD/DVD drives: Drives that play and/or record to CD ROMs or DVDs.

PCI cards: There are various types of PCI busses and PCI cards. The typical PCI cards used in desktop computers are video cards (to connect the motherboard to the monitor) and sound cards (to connect the motherboard to the speakers). Often the motherboard already has sound and video capabilities, but for high end gaming, graphics, or music a high performance PCI card will replace the onboard function to get better results.

What makes up the Motherboard?

The CPU: This is the brain of the computer. It runs instructions given to it by the software applications currently running. The CPU runs instructions at a certain clock speed that is usually given as a feature of the CPU and is in the unit of MHz (Megahertz) or millions of cycles per second. There are different sorts of CPUs. Most PCs today are run by CPUs made from Intel or AMD.

The chipset: The chipset is a family of chips that sit around the CPU and connect the CPU to the outside world. Often the chipset is divided up into a Northbridge and a Southbridge chip. The Northbridge connects to the CPU over the Front Side Bus (FSB) and connects the CPU to the memory (DRAM), the PCI bus, and the Southbridge chip. Sometimes the Northbridge as the video integrated. The Southbridge chip has the controls for the peripherals like USB, serial ports, sound, disk drives, etc. and often connects to the CPU through the Northbridge.

Memory: The computer has all sorts of memory on it. On the motherboard, the main memory is DRAM (Dynamic Random Access Memory). This is the high speed memory where the CPU keeps the programs it is currently running. The CPU will take the program from the hard disk drive and put it into the DRAM for high speed execution. The amount and speed of DRAM can greatly affect the overall performance of the computer. DRAM types and speeds vary depending on the CPU and chipset. DRAM comes on a little cards called DIMMs (Dual Inline Memory Module) that then plug into sockets on the motherboard.

BIOS: The BIOS (Basic Integrated Operating System) is the software that allows the computer to boot up. It's main function is to start up the computer and then load the main operating system off of the hard drive. The BIOS resides in a ROM or FLASH device on the motherboard. These are static memories, so they retain the software even when power is off.

What are all those peripheral connections on a computer?

A desktop computer can come with any number of peripheral ports. Some typical computer peripherals include:

For More Computer Information

Computer Software

How Does a Computer Work?

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