Computer Organization.

Regardless of differences in physical appearance, virtually every computer may be envisioned as being divided into six logical units or sections. these are:

1.Input unit. this is the "receiving"dection of the computer. it obtains information[data and computer programs ] from various input devices and places this information at the disposal of the other units so that the information may be processed. Most information is interred  computers today through typewriter-like key- boards,"mouse"devices and disks. In the future , most information will be interred by speaking to computers, by electronically scanning images, and by video recording.

2. output unit: This is the "shipping section of the computer. It takes information processed by the computer and places it on various output devices to make the information available for use outside the computer. information output from computer is displayed on screens, printed on paper, played through audio speakers, magnetically recorded on disks and tapes, or used to control other devices.

3.Memory unit: This is the rapid access, relatively low capacity"warehouse"section of the computer. it retains information that has been entered through the input unit so that the information may be made immediately available for processing when it is needed. The memory unit also retains information that has already been processed until that information  can be placed on output devices by the output unit. The memory unit is often called either memory, primary memory or random access memory[Ram].

4.Arithmetic and logic unit [Alu]. This is the "manufacturing" section of the computer. It is the responsible of performing calculations such as additions, subtraction, multiplication and division. It contains the decision mechanisms that allow the computer, for example, to compare two itemed from the memory unit to determine whether or not they are equal.

5.central processing unit [Cpu].  This is the "administrative" section of the computer. It is the computer's coordinator and is responsible for supervising 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 utilized in calculations and tells the output unit when to send information from the memory unit to certain output devices

6.secondary storage unit: This is the long- term , high- capacity "warehousing"section of the computer . programs or data not being used by the other units are normally placed on secondary storage device[such as disks] until they are needed, possibly hours, days, months or even years later. Information in secondary storage takes longer to access than Information in primary memory. The cost per unite of secondary storage is muss less than the cost per unite of primary memory.