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Computer components Computers are made up of three main parts: the input unit, the central processing unit (CPU), and the output unit. The CPU is the brain of the computer, and is made up of the Arithmetic Logic Unit (ALU), the Control Unit (CU), and the $7.99
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Computer components Computers are made up of three main parts: the input unit, the central processing unit (CPU), and the output unit. The CPU is the brain of the computer, and is made up of the Arithmetic Logic Unit (ALU), the Control Unit (CU), and the
Computer components
Computers are made up of three main parts: the input unit, the central processing unit (CPU), and the output unit. The CPU is the brain of the computer, and is made up of the Arithmetic Logic Unit (ALU), the Control Unit (CU), and the main memory.
Computer functions
Computer...
A computer system mainly has three components viz. Input Unit, Central Processing Unit and
Output Unit. These components are the building blocks of a computer and define its architecture.
Components of Computer
1. Input Unit
2. Central Processing Unit
3. Output Unit
1. Input Unit:
An input unit performs inputting operation. It carries out the following functions:
(a) It accepts (or reads) instructions and data from outside world.
(b) It converts these instructions and data to computer acceptable form. Units called input
interfaces accomplish this task.
(c) It supplies the converted instructions and data to the storage unit for storage and further
processing. Following are some of the important input devices which are used in a computer −
• Keyboard • Microphone
• Mouse • Magnetic Ink Card Reader (MICR)
• Joy Stick • Optical Character Reader (OCR)
• Light pen • Bar Code Reader
• Track Ball • Optical Mark Reader (OMR)
• Scanner
2. Central Processing Unit:
Once the information is entered into the computer by the input device, the processor processes it.
The CPU is called the brain of the computer because it is the control centre of the computer. It
first fetches instructions from memory and then interprets them so as to know what is to be done.
If required, data is fetched from memory or input device. Thereafter CPU executes or performs
,the required computation, and then either stores the output or displays it on the output device.
The CPU has three main components, which are responsible for different functions: Arithmetic
Logic Unit (ALU), Control Unit (CU) and Memory registers
A. Arithmetic and Logic Unit (ALU): A computer performs all calculation and comparison
(decision-making) operations in the ALU. During processing of a job, the computer transfers
data and instructions stored in its primary storage to ALU as and when needed. ALU does the
processing and the computer temporarily transfers the intermediate results generated there back
to primary storage until needed later. Hence, data may move back and forth several times
between primary storage and ALU before processing of the job is over. ALUs are designed to
perform the four basic arithmetic operations (add, subtract, multiply, and divide) and logic
operations or comparisons such as, less than, equal to, and greater than.
B. Control Unit: A computer’s control unit does not perform any actual processing of jobs, but
acts as the central nervous system for other components of the computer system. It manages and
coordinates the operations of all other components. It obtains instructions from a program stored
in main memory, interprets the instructions, and issues signals causing other units of the system
to execute them.
C. Memory Registers: A register is a temporary unit of memory in the CPU. These are used to
store the data, which is directly used by the processor. Registers can be of different sizes(16 bit,
32 bit, 64 bit and so on) and each register inside the CPU has a specific function, like storing
data, instruction, address in memory etc. Accumulator (ACC) is the main register in the ALU
and contains one of the operands of an operation to be performed in the ALU.
2. Output Unit :
An output unit performs outputting operation. It carries out the following functions:
(a) It accepts the produced results, which are in coded form. We cannot understand the coded
results easily.
(b) It converts these coded results to human acceptable (readable) form. Units called output
interfaces accomplish this task.
(c) It supplies the converted results to outside world.
Following are some of the important output devices used in a computer.
•Monitors
•Printer
•Speaker
•Projector
•Headphone
Memory or Storage Unit
A memory is just like a human brain. It is used to store data and instructions. Computer memory
is the storage space in the computer, where data is to be processed
Memory is primarily of three types −
•Cache Memory
•Primary Memory/Main Memory
, •Secondary Memory
1. Cache Memory
Cache memory is a very high speed semiconductor memory which can speed up the CPU. It acts
as a buffer between the CPU and the main memory. It is used to hold those parts of data and
program which are most frequently used by the CPU. The parts of data and programs are
transferred from the disk to cache memory by the operating system, from where the CPU can
access them.
The advantages of cache memory are as follows −
•Cache memory is faster than main memory.
•It consumes less access time as compared to main memory.
•It stores the program that can be executed within a short period of time.
•It stores data for temporary use.
2. Primary Memory (Main Memory)
Primary memory holds only those data and instructions on which the computer is currently
working. It has a limited capacity and data is lost when power is switched off. It is generally
made up of semiconductor device. These memories are not as fast as registers. The data and
instruction required to be processed resides in the main memory. It is divided into two
subcategories RAM and ROM.
RAM (Random Access Memory) is the internal memory of the CPU for storing data, program,
and program result. It is a read/write memory which stores data until the machine is working. As
soon as the machine is switched off, data is erased. Data in the RAM can be accessed randomly
but it is very expensive. RAM is volatile, i.e. data stored in it is lost when we switch off the
computer.
RAM is of two types:
• Static RAM (SRAM)
• Dynamic RAM (DRAM)
Static RAM (SRAM): SRAM Stand’s for static random access memory. Data remains in static
RAM as long as there is power supply.
Characteristic of Static RAM
• Long life
• No need to refresh
• Faster
• Used as cache memory
• Large size
• Expensive
• High power consumption
Dynamic RAM (DRAM): DRAM Stands for Dynamic Random Access Memory. Data can be
Stored in the DRAM only when it is refreshed frequently.
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