Introduction to Computer
Computer is an advanced electronic device that takes raw data as input from the user and processes it under the control of set of instructions (called program), gives the result (output), and saves it for the future use.
A computer system is made up of both hardware and software. Software is another term for computer program. Software controls the computer and makes it do useful work. Without software a computer is useless.
Hardware refers to the physical components that make up a computer system. These include the computer's processor, memory, monitor, keyboard, mouse, disk drive, printer and so on.
Functionalities of a computer
Any digital computer carries out five functions in gross terms:
✱ Takes data as input.
✱ Stores the data/instructions in its memory and use them when required.
✱ Processes the data and converts it into useful information.
✱ Generates the output
✱ Controls all the above four steps.
Definition
Computer is an electronic data processing device which
✱ accepts and stores data input,
✱ processes the data input, and
✱ generates the output in a required format.
Advantages
Following list demonstrates the advantages of computers in today's arena.
✱ High Speed
✱ Computer is a very fast device.
✱ It is capable of performing calculation of very large amount of data.
✱ The computer has units of speed in microsecond, nanosecond, and even the picosecond.
✱ It can perform millions of calculations in a few seconds as compared to man who will spend many months for doing the same task.
Accuracy
✱ In addition to being very fast, computers are very accurate.
✱ The calculations are 100% error free.
✱ Computers perform all jobs with 100% accuracy provided that correct input has been given.
Storage Capability
✱ Memory is a very important characteristic of computers.
✱ A computer has much more storage capacity than human beings.
✱ It can store large amount of data.
✱ It can store any type of data such as images, videos, text, audio and many others.
Diligence
✱ Unlike human beings, a computer is free from monotony, tiredness and lack of concentration.
✱ It can work continuously without any error and boredom.
✱ It can do repeated work with same speed and accuracy.
Versatility
✱ A computer is a very versatile machine.
✱ A computer is very flexible in performing the jobs to be done.
✱ This machine can be used to solve the problems related to various fields.
✱ At one instance, it may be solving a complex scientific problem and the very next moment it may be playing a card game.
Reliability
✱ A computer is a reliable machine.
✱ Modern electronic components have long lives.
✱ Computers are designed to make maintenance easy.
Automation
✱ Computer is an automatic machine.
✱ Automation means ability to perform the given task automatically.
✱ Once a program is given to computer i.e., stored in computer memory, the program and instruction can control the program execution without human interaction.
Reduction in Paper Work
✱ The use of computers for data processing in an organization leads to reduction in paper work and results in speeding up a process.
✱ As data in electronic files can be retrieved as and when required, the problem of maintenance of large number of paper files gets reduced.
Reduction in Cost
✱ Though the initial investment for installing a computer is high but it substantially reduces the cost of each of its transaction.
Disadvantages
Following list demonstrates the disadvantages of computers in today's arena
✱ A computer is a machine that has no intelligence to perform any task.
✱ Each instruction has to be given to computer.
✱ A computer cannot take any decision on its own.
Dependency
✱ It functions as per a user’s instruction, so it is fully dependent on human being
✱ Environment
✱ The operating environment of computer should be dust free and suitable.
✱ No Feeling
✱ Computers have no feelings or emotions.
✱ It cannot make judgment based on feeling, taste, experience, and knowledge unlike a human being.
Interaction between User and Computer
Human–computer interaction (HCI) involves the study, planning, design and uses of the interfaces between people (users) and computers.
HCI (human-computer interaction) is the study of how people interact with computers and to what extent computers are or are not developed for successful interaction with human beings.
HCI is a very broad discipline that encompasses different specialties with different concerns regarding computer development: computer science is concerned with the application design and engineering of the human interfaces; sociology and anthropology are concerned with the interactions between technology, work and organization and the way that human systems and technical systems mutually adapt to each other; ergonomics is concerned with the safety of computer systems and the safe limits of human cognition and sensation; psychology is concerned with the cognitive processes of humans and the behavior of users; linguistics is concerned with the development of human and machine languages and the relationship between the two.
Components of computer
All types of computers follow a same basic logical structure and perform the following five basic operations for converting raw input data into information useful to their users.
Sr.No. Operation Description
⦁ Take Input The process of entering data and instructions into the computer
system
⦁ Store Data Saving data and instructions so that they are available for
processing as and when required.
⦁ Processing Data Performing arithmetic, and logical operations on data in order to convert them into useful information.
⦁ Output
Information
⦁ Control the workflow
The process of producing useful information or results for the user, such as a printed report or visual display.
Directs the manner and sequence in which all of the above operations are performed.
Input Unit
This unit contains devices with the help of which we enter data into computer. This unit makes link between user and computer. The input devices translate the information into the form understandable by computer.
CPU (Central Processing Unit)
CPU is considered as the brain of the computer. CPU performs all types of data processing operations. It stores data, intermediate results and instructions(program). It controls the operation of all parts of computer.
CPU itself has following three components
ALU(Arithmetic Logic Unit)
Memory Unit
Control Unit
Output Unit
Output unit consists of devices with the help of which we get the information from computer. This unit is a link between computer and users. Output devices translate the computer's output into the form understandable by users.
Types of Computer
Computers can be broadly classified by their speed and computing power.
S.no. Type
1. PC (Personal Computer)
Specifications
It is a single user computer system having moderately powerful microprocessor
2. WorkStation It is also a single user computer system which is similar to personal computer but have more powerful microprocessor.
3. Mini Computer It is a multi-user computer system which is capable of
supporting hundreds of users simultaneously.
It is a multi-user computer system which is capable of
4. Main Frame:- supporting hundreds of users simultaneously. Software technology is different from minicomputer.
5. Supercomputer:- It is an extremely fast computer which can execute hundreds of millions of instructions per second.
PC (Personal Computer)
A PC can be defined as a small, relatively inexpensive computer designed for an individual user. PCs are based on the microprocessor technology that enables manufacturers to put an entire CPU on one chip. Businesses use personal computers for word processing, accounting, desktop publishing, and for running spreadsheet and database management applications. At home, the most popular use for personal computers is playing games and surfing Internet.
Although personal computers are designed as single-user systems, these systems are normally linked together to form a network. In terms of power, now-a-days High-end models of the Macintosh and PC offer the same computing power and graphics capability as low-end workstations by Sun Microsystems, Hewlett-Packard, and Dell.
Workstation
Workstation is a computer used for engineering applications (CAD/CAM), desktop publishing, software development, and other such types of applications which require a moderate amount of computing power and relatively high quality graphics capabilities.
Workstations generally come with a large, high-resolution graphics screen, large amount of RAM, inbuilt network support, and a graphical user interface. Most workstations also have a mass storage device such as a disk drive, but a special type of workstation, called a diskless workstation, comes without a disk drive.
Common operating systems for workstations are UNIX and Windows NT. Like PC, Workstations are also single-user computers like PC but are typically linked together to form a local-area network, although they can also be used as stand-alone systems.
Minicomputer
It is a midsize multi-processing system capable of supporting up to 250 users simultaneously.
Mainframe
Mainframe is very large in size and is an expensive computer capable of supporting hundreds or even thousands of users simultaneously. Mainframe executes many programs concurrently and supports many simultaneous execution of programs
Supercomputer
Supercomputers are one of the fastest computers currently available. Supercomputers are very expensive and are employed for specialized applications that require immense amount of mathematical calculations (number crunching). For example, weather forecasting, scientific simulations, (animated) graphics, fluid dynamic calculations, nuclear energy research, electronic design, and analysis of geological data (e.g. in petrochemical prospecting).
Number Systems
A number system is a system representing numbers. It is also called the system of numeration and it defines a set of values to represent a quantity. These numbers are used as digits and the most common ones are 0 and 1, that are used to represent binary numbers. Digits from 0 to 9 are used to represent other types of number systems.
Types of Number Systems
There are different types of number systems in which the four main types are:
✱ Binary number system (Base - 2)
✱ Octal number system (Base - 8)
✱ Decimal number system (Base - 10)
✱ Hexadecimal number system (Base - 16)
Decimal Number System
Decimal number system is a base 10 number system having 10 digits from 0 to 9. This means that any numerical quantity can be represented using these 10 digits. Decimal number system is also a positional value system. This means that the value of digits will depend on its position. Let us take an example to understand this.
Say we have three numbers – 734, 971 and 207. The value of 7 in all three numbers is different−
In 734, value of 7 is 7 hundreds or 700 or 7 × 100 or 7 × 102
In 971, value of 7 is 7 tens or 70 or 7 × 10 or 7 × 101
In 207, value 0f 7 is 7 units or 7 or 7 × 1 or 7 × 100
The weightage of each position can be represented as follows −
In digital systems, instructions are given through electric signals; variation is done by varying the voltage of the signal. Having 10 different voltages to implement decimal number system in digital equipment is difficult. So, many number systems that are easier to implement digitally have been developed. Let’s look at them in detail.
Binary Number System
The easiest way to vary instructions through electric signals is two-state system – on and off. On is represented as 1 and off as 0, though 0 is not actually no signal but signal at a lower voltage. The number system having just these two digits – 0 and 1 – is called binary number system.
Each binary digit is also called a bit. Binary number system is also positional value system, where each digit has a value expressed in powers of 2, as displayed here.
In any binary number, the rightmost digit is called least significant bit (LSB) and leftmost digit is called most significant bit (MSB).
And decimal equivalent of this number is sum of product of each digit with its positional value.
110102 = 1×24 + 1×23 + 0×22 + 1×21 + 0×20
= 16 + 8 + 0 + 2 + 0
= 2610
Computer memory is measured in terms of how many bits it can store. Here is a chart for memory capacity conversion.
✱ 1 byte (B) = 8 bits
✱ 1 Kilobytes (KB) = 1024 bytes
✱ 1 Megabyte (MB) = 1024 KB
✱ 1 Gigabyte (GB) = 1024 MB
✱ 1 Terabyte (TB) = 1024 GB
✱ 1 Exabyte (EB) = 1024 PB
✱ 1 Zettabyte = 1024 EB
✱ 1 Yottabyte (YB) = 1024 ZB
Octal Number System
Octal number system has eight digits – 0, 1, 2, 3, 4, 5, 6 and 7. Octal number system is also a positional value system with where each digit has its value expressed in powers of 8, as shown here −
Decimal equivalent of any octal number is sum of product of each digit with its positional value.
7268 = 7×82 + 2×81 + 6×80
= 448 + 16 + 6
= 47010
Hexadecimal Number System
Octal number system has 16 symbols – 0 to 9 and A to F where A is equal to 10, B is equal to 11 and so on till F. Hexadecimal number system is also a positional value system with where each digit has its value expressed in powers of 16, as shown here −
Decimal equivalent of any hexadecimal number is sum of product of each digit with its positional value.
27FB16 = 2×163 + 7×162 + 15×161 + 10×160
= 8192 + 1792 + 240 +10
= 1023410
How to convert a number from one base to another?
Follow the example illustrations:
1. Decimal to Binary
(10.25)10
Note:- Keep multiplying the fractional part with 2 until decimal part 0.00 is obtained.
(0.25)10 = (0.01)2
Answer:- (10.25)10 = (1010.01)2
2. Binary to Decimal
(1010.01)2
1x23 + 0x22 + 1x21+ 0x20 + 0x2 -1 + 1x2 -2 = 8+0+2+0+0+0.25 = 10.25
(1010.01)2 = (10.25)10
3. Decimal to Octal
(10.25)10
(10)10 = (12)8
Fractional part:
0.25 x 8 = 2.00
Note:- Keep multiplying the fractional part with 8 until decimal part .00 is obtained.
(.25)10 = (.2)8
Answer:- (10.25)10 = (12.2)8
4. Octal to Decimal
(12.2)8
1 x 81 + 2 x 80 +2 x 8-1 = 8+2+0.25 = 10.25
(12.2)8 = (10.25)10
5. Hexadecimal to Binary
To convert from Hexadecimal to Binary, write the 4-bit binary equivalent of hexadecimal.
(3A)16 = (00111010)2
6. Binary to Hexadecimal
To convert from Binary to Hexadecimal, start grouping the bits in groups of 4 from the right-end and write the equivalent hexadecimal for the 4-bit binary. Add extra 0’s on the left to adjust the groups.
1111011011
0011 1101 1011
(001111011011 )2 = (3DB)16
No comments:
Post a Comment