How Computers Works 

A computer is a device that can perform computations and make logical decisions phenomenally faster than human beings can. Many of today's personal computer can perform billions of calculations in one second.

Computers process data under the control of sets of instructions call computer programs. These programs guide the computer through orderly sets of actions specified by people called programmers. The programs that run on a computer are referred to as software. A computer consists of various devices referred to as hardware (e.g., the keyboard, screen, mouse, speakers, CPU etc.) and can be divided into various logical unit or sections.

Input Unit

The receiving section obtains information (data and computer programs)

from input devices and places it at the disposal of the other units for processing.

Most information is entered into computers through keyboards, touch screen and mouse devices, Other forms of input include speaking to your computer, scanning images and barcodes, reading from secondary storage devices (like hard drives, DVD drives, Blu-ray Disc™ drives and USB flash drives also called thumb drives or  memory sticks), receiving video from a webcam and having your computer receive information from the internet ( such as when you download video from Youtube™ or e-books from Amazon). Newer forms of input include reading position data from a GPS device, and motion and orientation information from an accelerometer in a smartphone or game controller.

Output unit

This shipping  section takes information that the computer has processed

And places it on various output devices to make it available for use outside the computer. Most information that’s output from computers today is displayed on screens, printed on paper , played as audio or video on portable media players (such as Apple’s popular iPods) and giant screens in sports stadiums, transmitted over the Internet or used to control other devices , such as robots and intelligent appliances.

Memory unit

This rapid access, relatively low-capacity warehouse section retains information that has been entered through the input unit, making it immediately available for processing when needed. The  memory unit also retains processed information until it can be placed on output devices by the output unit. Information in the memory unit is volatile it’s typically lost when the computers power is turned off. The memory unit is often called either memory or  primary memory.

Arthimetic and logic unit (ALU)

This manufacturing section performs calculations, such as addition, subtraction, multiplication and division. It also contains the logical unit that perform decisions mechanisms that allow computer to compare two items from the memory unit to determine whether they are equal or not.

Centeral Processing Unit (CPU)

This  administrative  section coordinates and supervises the operation of the other sections. The cpu tells the input unit when information should be read into the memory unit, tells the ALU when information from the memory unit should be used in calculations and tells the output unit when to send information to memory unit to certain output devices.

Secondary storage unit

This is the long term high-capacity warehousing section. Programs or data not actively being used by other units normally are placed on secondary storage devices (e.g., your hard drive) until they’re again needed, possibly hours, days, months or even years later. Information on secondary storage devices is persistent it’s preserved even when the computer’s power is turned off.