Computer System

computer-system

Block diagram of a Computer System

Input & Output Device:

Input Device: The device through which a computer takes input is called as Input Device.

Example:

Mouse, Keyboard, Scanner, Joy stick, Driving Wheel, Screen touch monitor, light pen, Microphone etc.

Output Device: The device through which a computer gives only information to its user is called output device.

Example:

Monitor, Speaker, Printer and Plotter etc.

CPU (Central Processing Unit):

CPU is the main processing unit of a digital computer. The data taken by input device is processed here and turned into information.

There are three main components in CPU;

  • ALU (Arithmetic logic unit).
  • CU (Control unit).
  • Register.

ALU (Arithmetic logic unit): ALU is the main block which does all types of arithmetic operation. Some logical operation is also done by ALU.

CU (Control unit): Control unit is the main control portion of a computer. It controls which task or work will be done at first.

Register: Register is one type of memory which is situated within CPU.

Memory:

Memory is the main portion where all kinds of data are stored. CPU takes data from memory when it wants.

classification-of-memory

Classification of Computer Memory

Primary Memory Primary memory stored information for a certain period. When the power goes off all the information erased from the memory.

RAM (Random Access Memory): The information stored in RAM depends on the electric power. When the power goes off all the information get removed from RAM. RAM is also called as volatile memory.

  • S-RAM (Static RAM): S-RAM is fast and expensive. Storage space is low.
  • D-RAM (Dynamic RAM): D-RAM is slower and cheaper than S-RAM. D-RAM has high storage space.

ROM (Read only Memory): All the things are stored into ROM using logic gate. ROM is non-volatile type. So, if the power goes off all the things will be still stored in ROM. Different types are ROM are there;

  • E. ROM(Erasable ROM)
  • P. ROM(Programmable ROM)
  • E.P ROM(Erasable Programmable ROM)
  • E.E.P ROM(Electronically Erasable Programmable ROM)

Cache Memory Cache Memory is very high speed storage unit. It is placed between CPU and Main Memory. It works as a buffer in high speed computer. Cache Memory is costlier than main memory. There are three types of cache memory;

  • Asynchronous SRAM.
  • Synchronous Burst SRAM.
  • Pipeline Burst SRAM.

Secondary Memory To store huge amount of information secondary memory is needed.

Example:

Magnetic Media, Floppy Disk, Hard Disk, Compact Disk.

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