The Atanasoff Berry Computer (ABC) was the first Electronic Digital Computer
Computer is an Electronic Data Processing machine which receive and stores large volumes of information in the form of digit (binary) and process them as per the instructions at a very high speed and produces the desired result with preselected degree of accuracy.
The internal architectural design of computers differs from one system model to another. The basic organization remains the same for all computer systems. The digital computer is a digital system that performs various computational tasks. The word digital implies that the information in the computer is represented by variables that take a limited number of discrete values. Digital Computers work on the principle of counting of numbers.
The major components of a digital computer are
A) Input Unit
B) Output Unit
C) Central Processing Unit (C.P.U)
D) Memory Unit
E) Arithmetic Logic Unit (ALU)
F) Control Unit
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A) Input Unit:
An input unit is a device which accepts the information from the user and communicates these to the computer. Information is entered in to a computer through input devices. An input device converts input information into suitable binary form acceptable to a computer.
This is the process of entering data and programs in to the computer system. The computer is an electronic machine like any other machine which takes as inputs data and performs some processing giving out processed data. Therefore, the input unit takes data from us to the computer in an organized manner for processing. Input unit present data to the C.P.U in machine readable form.
Commonly used Computer Input Devices :
- Digital camera
- Keyboard
- Microphone
- Mouse
- Scanner
- Web
Cam - Light pen
- Joy stick etc.,
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B) Output Unit:
This output unit receives information from the C.P.U and present it to the user in the desired form. The output unit or output device receive result and other information from the computer and provides them to user. This is the process of producing results from the data for getting useful information. The computer sends information to an output device in the binary form. The output produced by the computer after processing must also be kept somewhere inside the computer before being given to you in human readable form. The output is also stored inside the computer for further processing.
Commonly used Computer Output Devices :
- Monitor
- Printer
- Plotter
- Speaker
- Projector etc.,
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C) Central Processing Unit (CPU):
The CPU is the brain of any computer system. The Microprocessor or CPU is the computer's most important component. It does all the thinking for the p.c. and runs the programs. It receives data and instructions, store them temporarily then process the data as per the instructions. It controls the operation of all other components such as memory, input and output devices.
1) Memory Unit :
It is a device that can accept data or instruction, hold them and deliver then on demand at a later time. The memory unit is also referred as primary storage. The function of the memory is to store information. It stores program, data, results or any other kind of information.
2) Arithmetic Logic Unit (ALU):
This unit is used to perform all the arithmetic and logic operations, such as addition, subtraction, multiplication, division, logic and comparison, etc.,
3) Control Unit:
This unit controls the activities of all other units in the system. It receives the instructions one by one, from the program which is stored in memory. For each instruction, it informs the ALU to execute the operations specified by the instruction. It also controls the parts of computer such as input devices, output devices and secondary memory devices. It’s main function is control the transfer of data and information between various units.
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