Republic of Uzbekistan Ministry of Higher and Secondary Special Education Samarkand State University Faculty of International Educational Programs Department of Computer Science and Programming Technologies independent work

Output unit

An output unit consists of output devices such as monitor, printer, and speaker. The output devices display the result (which is obtained after processing the data) to the user in an understandable manner.
The various output devices include:

• 
  Monitor
  
• 
  Printer
  
• 
  Speaker
  

Monitor

Monitor is the electronic visual display for computers. It is the most important output device of a computer. Without monitor we cannot see what computer is doing or performing inside. Monitor is also sometimes referred as computer monitor or computer display. Computer monitors are of two types: CRT (Cathode Ray Tube) monitor and LCD (Liquid Crystal Display) monitor.

Memory unit

Like the human brain, computers also store the information. Memory unit is used for storing digital data for future use. Computer memory stores the information temporarily or permanently. 
Computer memory is mainly classified into two types:

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  Primary memory 
  
• 
  Secondary memory
  

Primary memory

The primary memory is used to hold pieces of program, data, and an instruction on which computer is currently working. It also stores the intermediate and final results of processing. After completing the processing, the obtained results are transmitted to the output device.
The primary memory stores the data only when the power is on. When there is no power the data stored in the primary memory will be lost. The primary memory is also sometimes referred as main memory, temporary memory or volatile memory. This memory works faster than secondary memory. RAM is an example of primary memory. The primary memory of modern computers is made of semiconductor devices.

Secondary memory

The secondary memory is also called as non-volatile memory or permanent memory. It works slower than the primary memory. However, it stores the data permanently.
Secondary memory stores the data even if the power is turned off. Secondary memory has high storage capacity than the primary memory.
The secondary memory stores operating system, text files, images, songs, videos, etc. The Central Processing Unit (CPU) does not read the information directly from the secondary memory. The information stored in the secondary memory is first transmitted to the primary memory. After that, the CPU reads the data from the primary memory. The secondary memory is much cheaper than the primary memory. Optical disks, magnetic disks, and magnetic tapes are examples of secondary memory.