1. Introduction To Computer
Presented By:
Pradyumna Bhattarai
Roll no:27
Bsc.CSIT 1(st) Semester

2. Introduction To Computers
Types of Computers
Characteristics
What computer can do and can’t do?

3. Introduction Computer System:
“COMPUTER” i.e. Commonly Operated Machine Particularly Used For Trade Education And Research
Computer is derived from Latin word “computare” which means to calculate.
It is an electronic device which accepts raw data given by us , process them and gives meaningful result as output , provided that the instruction given by us is correct.
Computer does the work with 100% accuracy and works with high speed .
It work as :
Computer System:
As our body has different system , computer also has different system that helps the computer to perform its task in efficient, easier and in convenient way.
Input
Process
output

4. Computer System The computer system has mainly five components :
1.Processor:It is the brain of computer also referred as CPU.
It carries out instructions given by user or software.
2.Memory: It is like the chips which is needed to load and to
lunch the programs.
If the memory is not present then computer will be useless.
3.Input device :The devices that accepts data and instruction from users are input devices. Some examples of them are keyboard, mouse ,scanner, light pen , microphones, etc..
4.Output device: The devices that give result of the inputted data to us are output devices. Some examples of them are monitors, printers, speakers, etc..
5.Storage: It holds data and stores our files. It helps us to store large amount of data and files permanently. Some commonly used storage devices are Hard Disk drives , CD drives , etc.

5. Types of Computer
During the course of development of computer that we are using nowadays , it has undergone many changes as in size, storage capacity and many more features.
There are different types of computer according to size and power. They are :
1.Personal Computer:
A. It is the computer based on microprocessor .
B. It is small and only single use.
C. A personal computer may be a desktop computer or a laptop, Notebook,  tablet or a palm top.

6. 2.Workstation:
It is based on microprocessor but powerful than that of personal computer.
It is also an single use and has high quality monitors.
Workstations offered higher performance than mainstream personal computer , especially with respect to CPU and graphics memory capacity and multitasking capability.

7. Types of computer: 3.Minicomputers:
It is the computer which can be used by multiple user.
It is used in manufacturing process control, telephone switching and to control laboratory equipment.
It grew to have relatively high processing power and capacity. 

8. Types of computer: 4.Supercomputers:
It is the computer which can perform millions of instruction per second .
It is extremely fast than any of the others.
 It is used for a wide range of computationally intensive tasks in various fields, including quantum mechanics, 
weather forecasting climate research
oil and gas exploration molecular
modeling.

9. 5.Mainframe: A. It supports many users to perform task.
B. It is primarily used by corporate and governmental organizations for critical applications, bulk data processing.
C. Mainframes are designed to
handle very high volume input
and output (I/O) and emphasize
throughput computing.
D. Their high stability and reliability
enables these machines to run
uninterrupted for decades.

10. Characteristics of computer
1.Speed,Size and cost:
They depend upon the technology used to build them.
The computer build by using vacuum tubes has large size, less speed and high cost.
But the computers build by using transistors and IC’s are small in size , faster and are not as costly as computers build by using vacuum tubes.
Units of time
Abbreviation
Fraction of a second
Millisecond ms
Thousandth: 0.001
Microsecond µs
Millionth:
Nanosecond ns
Billionth:
Picosecond ps
Trillionth:

11. Characteristics of computer
2.Accuracy and reliability:
Computers are never tired and can run in fast speed without any errors unless the instructions given by the user is correct.
Computers built with integrated circuits are more reliable. They have a low failure rate.
Computers are most suitable to handle repetitive tasks because they do not take tea breaks and sick leaves, and they never complain.
For example, the automatic teller machines (ATM) are in operation 24 hours a day, 7 days a week.
If inaccurate data is entered, the computers will generate incorrect results. This is known as "Garbage In; Garbage Out" (GIGO).
For example, the item prices determined by scanning the bar-codes at the point-of-sale terminals in supermarkets are far more accurate than those typed in by cashiers.

12. Characteristics of computer
3.Vast storage capacity:
Computer can store large amount of data and the storage can be divided into primary and secondary storage.
A diskette of 1.44 MB capacity can store 300 pieces of composition of 500 words each.
Units of storage
Abbreviation
Number of bytes
Kilobyte KB
1,024 or (210)
Megabyte MB
1,048,576 or (220)
Gigabyte GB
1,073,741,824 or (230)
Terabyte TB
About one trillion or (240)
Petabyte PB
8 Bits
1 Byte
1024 Bytes
1 Kilobyte
1024 Kilobytes
1 Megabyte
1024 Megabyte
1 Gigabyte
1024 Gigabytes
1 Terabyte
1024 terabyte
1 petabyte

13. Characteristics of computer
4.Automatic:
Everything is performed by the computer automatically as the user provides the data and instruction.
Computer runs automatically an it loads programs automatically as the user provide the instruction.

14. Characteristics of computer
5.Diligent:
The computer can run again and again without getting tired .
The computer never becomes tired and can perform many functions .

15. Characteristics of computer
6.Versatile:
The computer is versatile machine and it can perform many functions at a time.
At the same time songs can be played , files can be copied and documents can be processed.

16. Characteristics of computer
7.Non-intelligent:
Computer cannot work itself unless the user provides data and instruction.
 It is us to decide what we want to do and in what sequence. So a computer cannot take its own decision as we can.

17. What computer can do????
A computer can do lots of mathematical problems which cannot be solved by human.
A computer can work for long time without getting tired.
A computer never makes mistake unless the data provided is correct.
A computer can do many works at a time as human cannot do.
A computer can be used in every fields to keep data and instruction.

18. What computer cannot do????
Since computer is a machine , it cannot work in its own. User has to provide data .
The computer cannot think like humans and does it works according to the information provided by the user.
The computer cannot distinguish between right and wrong and does its work according to the instruction given by user.
As human being can take care of themselves , computer cannot take care itself. It is human that take care of computer.