How a Computer Works
Input devices:
Input devices enter information into the PC's System Unit.
Common types of input devices include the keyboard and mouse.
System Unit:
Is the box which contains the CPU and RAM. It is where the information from
the input devices gets processed.
CPU (Central Processing Unit): Electronically processes the incoming information.The CPU is a complex microelectronic switch which evaluates the incoming signal and instructs other PC components to take certain actions.
RAM (Random Access Memory): RAM is temporary electronic memory located inside the CPU that stores information.
Output devices:
The CPU sends signals to the output devices. The output devices then display
the information. Common types of output devices include the monitor, printer,
and speakers.
Storage: A storage device is used to save a permanent copy of documents. Common types of storage devices include floppy disks and hard disks. You may also store data on zip disks and CD-ROMS.
When a key on the keyboard or a button on the mouse is pressed, the input device sends an electronic signal to the System Unit. The System Unit contains the CPU, which is the "brain" of the computer. When the CPU processes information, it stores the needed data or instructions in RAM, which is the electronic memory in the System Unit. The PC's ability to store information electronically is what enables it to process that information so quickly. The CPU also tells the output device such as a monitor or printer, what to do. For example, when the letter "a" is typed, the corresponding electronic signal is sent to the CPU. The CPU stores that signal in RAM or electronic memory and instructs the monitor, which is an output device, to display the letter "a".
The final piece of the puzzle is storage. As a document is created, the computer temporarily stores that document electronically in RAM. The problem is that RAM is temporary - it is cleared whenever a program is exited or the PC is turned off. Thus, a storage device is needed to save a permanent copy of the document. If a word processing program is being used to write a letter, a permanent copy of the letter should be saved to a disk before quitting the program.
The two most common storage devices are hard disks and floppy disks. They store the document in a magnetic form, which enables them to keep it permanently, even after exiting the program and turning off the PC. Other storage devices include Network drives and Zip drives.