Computer System : Class 11 NEB Notes

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Concept, Importance and Characteristics of Computer

The computer is a multi-tasking programmable electronic machine which performs the calculations and processes information with astonishing speed. It can calculate thousands of informations with flash speed and almost unfailing accuracy. The computer can perform both computation and logical action at enormous speed. The two principle characteristics of a computer are:

• It responds to a specific set of instructions in a proper manner.
• It can execute a prerecorded list of instruction (a program)

A computer is an electronic device that manipulates information, or data. It has the ability to store, retrieve, and process data.

Hardware and software

• Hardware is any part of your computer that has a physical structure, such as the keyboard or mouse. It also includes all of the computer's internal parts, which you can see in the image below.
   
• Software is any set of instructions that tells the hardware what to do and how to do it. Examples of software include web browsers, games, and word processors. Below, you can see an image of Microsoft PowerPoint, which is used to create presentations.

IMPORTANCE OF COMPUTER

The computer is important in a variety of ways. For example, a difficult and time-consuming task can be done in no time and in an easy way. The computer provides better and effective way to manage a large amount of information to every individual, organization, business, government and institution. The value of computer lies in the ability to perform quickly and accurately. The computer can help in producing better quality products, help in teaching and assist in elimination human error.

a.) Solving numerical problems

One of the most difficult and most important jobs performed by computers is the solution of complicated problems involving numbers. computers can solve those problems amazingly and quickly. The computer can perform a simple numerical problem to complicated numerical problem.

b.) Storing and retrieving information

People use computers to store large quantities of information. information stored on a computer is sometimes called a database. The database can be enormous. For example, a country's entire census might be contained in a single database. A computer can search a huge database to find a specific piece of information. In addition, the information can be changed easily and quickly. The efficiency with which computers store and retrieve information makes them valuable in a wide range of professions.

c.) Creating and displaying document and picture

Computers can store a huge number of words in a way that make it easy to manipulate them. For this reason, word processing is one of the most important and widespread uses of a computer. Computers are also important in the publishing industries. For example, most books and magazine are typed on a computer. Graphics is the use of a computer to make pictures.

CHARACTERISTICS OF COMPUTER

The computer is not just adding machines; they are capable of doing complex activities and operations. They can be programmed to do complex, tedious and monotonous tasks. Computers are what they are because of the following characteristics:

i.) Word length

A digital computer operates on binary digits i.e 0 and 1. It can understand information only in terms of 0s and 1s. A binary digit is called a bit. a group of 8 bits is called a byte. The number of bits that a computer can process at a time in parallel is called its word length. Commonly used word length are 8,16,32 or 64 bits. Word length is the major of the computing power of a computer. When we talk of a 32-bit computer, it means that it's word length is 32 bits.

ii.) Speed

The calculation in the computer is at very high speeds. For example, a micro computer can perform millions of instructions per second as many times without any mistake. The speed increases, as the power of computer increase. For example, a super computer can operate at speed measures on nanoseconds and even picosecond.

iii.) Storage

The computer has main memory and auxiliary memory. The computer can store a large amount of data. With more and more auxiliary storage devices, which are capable of storing huge amounts of the data, the storage capacity of a computer is virtually unlimited. The reason that makes computer storage unique is not that it can store huge amount of data, but the fact that it can retrieve the information that the user wants in a few seconds. For example, computer dictionaries are available and the contents of this software version are the same as that of the printed dictionary.

iv.) Accuracy

The accuracy of a computer is very high unless the input is given correctly. In most cases, the error is because of human factor rather that technology mistake. For example, if the person input wrong code or the data is corrupted,the processing result is also wrong or corrupted. So if wrong input is given, the output also will be wrong- GIGO (Garbage In Garbage Out)

v.) Versatility

Computers can perform activities ranging from simple calculation like arithmetic calculation, to a complex calculation like launching a missile, which it makes a computer a versatile machine. some application area of computers like a business, bank medical diagnosis, science and technology,communication and astronomy, so it is a versatile machine.

vi.) Diligence

Diligence means being constant and determined in effort and application. The computer can perform the repetitive task without being a bore and it never gets tired. It can work continuously for several hour or day without getting bored and tired. Unlike human beings, a computer is free from tiredness, weakness, lack of concentration and monotony. Computers can perform activities ranging from simple calculation like arithmetic calculation, to a complex calculation like launching a missile, which it makes a computer a versatile machine.

vii.) Automation

A computer is an automatic machine, capable of functioning automatically once they are an appropriate set of instruction and data provided to the computer. Once the task is initiated on a computer it can proceed continuously. The computer can be programmed to perform a series of a task involving multiple programs. Computers are capable of these levels of automation if the instruction is provided correctly.

viii.) Reliability

Computers are used widely as they are reliable. The computer never gives the wrong result as long as the input is given correctly. The probability of error in the computer is negligible. A Huge amount of verities of data like monetary transaction, banking account, personal information is stored in a computer with the strong reliability to the computer.

The computer has become an integral part of our lives and is helping us in improving the standard living, enhancing the quality products, providing better healthcare, assisting in teaching and learning and other however computer have many limitations like lack of intelligence, lack of reasoning capabilities and other.

i.) Word length

A digital computer operates on binary digits i.e 0 and 1. It can understand information only in terms of 0s and 1s. A binary digit is called a bit. a group of 8 bits is called a byte. The number of bits that a computer can process at a time in parallel is called its word length. Commonly used word length are 8,16,32 or 64 bits. Word length is the major of the computing power of a computer. When we talk of a 32-bit computer, it means that it's word length is 32 bits.

ii.) Speed

The calculation in the computer is at very high speeds. For example, a micro computer can perform millions of instructions per second as many times without any mistake. The speed increases, as the power of computer increase. For example, a super computer can operate at speed measures on nanoseconds and even picosecond.

iii.) Storage

The computer has main memory and auxiliary memory. The computer can store a large amount of data. With more and more auxiliary storage devices, which are capable of storing huge amounts of the data, the storage capacity of a computer is virtually unlimited. The reason that makes computer storage unique is not that it can store huge amount of data, but the fact that it can retrieve the information that the user wants in a few seconds. For example, computer dictionaries are available and the contents of this software version are the same as that of the printed dictionary.

iv.) Accuracy

The accuracy of a computer is very high unless the input is given correctly. In most cases, the error is because of human factor rather that technology mistake. For example, if the person input wrong code or the data is corrupted,the processing result is also wrong or corrupted. So if wrong input is given, the output also will be wrong- GIGO (Garbage In Garbage Out)

v.) Versatility

Computers can perform activities ranging from simple calculation like arithmetic calculation, to a complex calculation like launching a missile, which it makes a computer a versatile machine. some application area of computers like a business, bank medical diagnosis, science and technology,communication and astronomy, so it is a versatile machine.

vi.) Diligence

Diligence means being constant and determined in effort and application. The computer can perform the repetitive task without being a bore and it never gets tired. It can work continuously for several hour or day without getting bored and tired. Unlike human beings, a computer is free from tiredness, weakness, lack of concentration and monotony. Computers can perform activities ranging from simple calculation like arithmetic calculation, to a complex calculation like launching a missile, which it makes a computer a versatile machine.

vii.) Automation

A computer is an automatic machine, capable of functioning automatically once they are an appropriate set of instruction and data provided to the computer. Once the task is initiated on a computer it can proceed continuously. The computer can be programmed to perform a series of a task involving multiple programs. Computers are capable of these levels of automation if the instruction is provided correctly.

viii.) Reliability

Computers are used widely as they are reliable. The computer never gives the wrong result as long as the input is given correctly. The probability of error in the computer is negligible. A Huge amount of verities of data like monetary transaction, banking account, personal information is stored in a computer with the strong reliability to the computer.

The computer has become an integral part of our lives and is helping us in improving the standard living, enhancing the quality products, providing better healthcare, assisting in teaching and learning and other however computer have many limitations like lack of intelligence, lack of reasoning capabilities and other.

GENERATIONS OF COMPUTERS

Computer generations classification is mainly based on the basic devices used. Also, the considerations are the architecture, languages, modes of operation, etc. The function performed by the computer and the speed of their operations have been changing since the old days to the most modern computer. Based on the period of development and the features incorporated, the computers are classified into different generations- First generation to Fifth generation. This is called the computer generation.

The classification and time periods are given below:

1. First Generation Computer (1945-1955)
2. Second Generation Computer (1957-1963)
3. Third Generation Computer (1964-1971)
4. Fourth Generation Computer (1972 onward)
5. Fifth Generation Computer (Present and future)

1.) First Generation Computer (1945-1955)

First generation computers were characterized by the fact that operating instructions were made to order for the specific task for which the computer was to be used. It was operated on the ' Principle of Thermionic Emission".

In the first generation computer, vacuum tubes as CPU, magnetic drum for data storage , and machines languages were used for giving instruction.The computer of this generation was very large in size called room-sized computers.

The programming of first generation computers was done in machine languages (0s and 1s). Afterward, assembly languages were developed and used in first generation computer.

Features of first generation computers:

• Technology used: vacuum tube
• Machines languages were used to instruct the computer.
• Magnetic core memory was used as primary memory.
• Electrostatic tubes, Parer tape, punch card, magnetic tape
• Punched card, printing devices were used for input/output operations and store the result.
• It occupies very large space, slow processing, inefficient and unreliable due to low accuracy.
• Power consumption was very high and it generated much heat.
• It could only perform straight forward simple numerical calculation.
• Computer used to be much expensive.

The example of first generation computers is ENIAC, UNIVAC,EDVAC, and EDSAC.

2.) Second Generation Computer (1957-1963)

Second generation computer replaced machine language with assembly language, allowing abbreviated programming codes to replace long, difficult binary codes.

The transistor was developed in this generation. A transistor transfers electric signals across a resistor. A transistor was highly reliable compared to tubes.

The transistor was far more superior in performance on account of their miniature size, smaller power consumption, and heat production rate. The second generation computer used these semiconductor devices.

Some of its features are:

• Technology used: Transistor
• Operating speed was in terms of a microsecond.
• Assembly language and machines independent language such as COBOL (Common Business Oriented Language) and FORTRAN (Formula Translation) were introduced the size of the computer.
• Magnetic core memory was used as primary memory.
• Magnetic drum and magnetic tape were used as secondary memory.
• Power required to operate them was low.
• It could perform scientific calculation such as solving differential equations.
• Storage capacity and use of computers are increased.

3.) Third Generation Computer (1964-1971)

Transistors were an improvement over the vacuum tube, but they still generated a great heat, which damaged the computer's sensitive parts. The quartz eliminated this problem.

Transistors were replaced with an integrated circuit known popularly as chips. Scientist managed to fit many components on a single chip. As a result, the computer became ever smaller as more components were squeezed on the chip.

IC was first designed and fabricated by Jack S Kilby at Texas Instrument and by Robert S Noyce at Fairchild independently. IC is a circuit consisting of a large number of electronic components placed on a single silicon chip by a photo-lithographic process.

Magnetic disks began to replace magnetic tape for auxiliary and video display terminals were introduced for the output of data. Keyboards were used for the input of data. A new operating system was introduced for automatic processing and multi-programming.

These computers were highly reliable, relatively expensive and faster. High-level programming languages continued to be a developer. The example of third generation computers is IBM-360 series, ICL-900 series, and Honeywell 200 series.

 

Features of the third generation computers are:

• The technology used: IC (Integrated Circuit).
• Transistors were replaced by IC in their electronic circuitry.
• High-level languages like FORTAN , BASIC and other are used to develop programs.
• Semiconductor memory like RAM and ROM were used as primary memory.
• Monitor and keyboard were introduced for data input and output respectively.
• Multiprogramming facility was developed.
• The computer was used in census calculation, military, banks and industries.
• Size, cost, power requirement and heat generation decreased.

4.) Fourth Generation Computer (1972 onward)

The invention of microprocessor chip marked the beginning of the fourth generation computers. Semiconductor memories replaced magnetic core memories. The invention of microprocessors led to the development of microcomputer or the personal computer.

The first microprocessor called Intel 4004 was developed by American Intel Corporation 1971.

This computer has faster generation language and application software for microcomputers became popular and allowed home and business users to adapt their computers for word processing, spreadsheet manipulating, file handing and graphics.

In this generation, the concept of computer networks and CD-ROMs came into existence.

Features of the fourth generation computer are:

• Technology in use: VLSI is introduced and used Microprocessor-based technology.
• Problem-oriented fourth generation language (4GL) is used to develop the program.
• Semiconductor like RAM, ROM and cache memory is used as a primary memory.
• Magnetic disks like hard disk, optical disk (CD,DVD), Blue-ray disk, flashes memory (memory chip, pen drive) are used as secondary memory.
• E-mail, Internet and mobile communication are developed.
• Advanced, user-friendly, web page software are developed.
• Size, cost, power requirement, heat generation decreased compared to the previous generation.
• Operating speed, storage capacity ,use of computer increased compared to the previous generation

The example of the fourth generation computer is IBM-PC, HP laptops, Mac notebook etc.

5.) Fifth Generation Computer (Present and future)

The aim is to bring machines with genuine IQ, the ability to reason logically and with real knowledge of the word. Thus, this computer will be totally different, totally novel and totally new than last four generations of computer.

Fifth generation computer are based on Artificial Intelligence (AI) and that is still developing process, but not yet a reality i.e this computer is incomplete. The scientists are working on it still.And till date many differnt Ai systems are developed and are being used in different application fields.

These computers will be able to converse with people and will be able to mimic human sense, manual skills, and intelligence.

Features of the fifth generation computers are:

• Technology to be used: These machines will incorporate Bio-chip and VVLSI (Very Very Large Scale Integration) or Ultra-Large Scale Integration (ULSI)
• The computer will have Artificial Intelligence (AI).
• Natural language will be used to develop programs.
• The computer will have parallel processing in full fledge.
• The operating speed will be in terms of LIPS(Logical Inference per Second)
• These aim is to solve highly complex problems, which require great intelligence and expertise when solved by people.
• Quantum computation, molecular and nanotechnology will be used completely.

Components of Computer System: Input, output, Processor and Storage

COMPONENTS OF COMPUTERSYSTEM

The computer is a device that operated upon information or data. It is an electronic device which accepts inputs data, stores the data, does arithmetic and logic operations and provides the outputs in the desired format. The computer receives data, process it, produces output and stores it for further references. So, a computer should have at least four major components to perform these tasks. A block diagram of the basic computer organization has the following functional units.

Fig(i->p->o)

Input Unit

The input unit is formed by the input devices attached to the computer. Input devices are used to interact with a computer system or used enter data and instructions to the computer. These devices convert input data and instructions into a suitable binary form such as ASCII, which can be acceptable by the computer. In brief, an input unit performs the following function:

• It accepts data and instruction from the outside worlds.
• It converts these data and instruction into computer understandable from a binary form.
• It supplied the converted data and instruction to the computer system for further processing.

E.g of input devices are keyboard, mouse, scanner etc.

Memory Unit

This unit is also called storage unit. The data and instructions, which are entered through an input unit must be stored on the computer before the actual processing starts. The result produces by the computer after processing is also kept somewhere before passed to the output units. If intermediate results are produced during processing, it should be stored in somewhere in memory. The storage unit of a computer performs all these needs. In brief, the specific functions performed by the storage unit are as follow:

• It stored data and instructions, which are entered through input devices.
• It stores an intermediate result of processing.
• It stores the final result of processing before these results are passed to an output device.

The storage unit of computers consists of two types of memory or storage: primary and secondary storage:

i. Primary Storage

Memory storage that communicates directly with CPU is called main memory. It enables the computer to store, at least temporarily data and instruction. It is mainly used to hold data and instructions and as well as the intermediate result of processing which the computer system is currently working on. Primary memory is volatile, that is, it lose its content when power supply is off. The Random access memory (RAM) is an example of a primary to main memory.

 

ii. Secondary Storage

Auxiliary storage is also known as secondary storage. It is the memory that supplements the main memory. These are a non-volatile memory. It is mainly used to transfer data to program from one computer to another computer. There is high capacity storage devices used to store data and program permanently. These are also used as backup devices which allows to store the valuable information as backup on which you are working on. The examples of secondary memory are Magnetic Disk, Optical disk, etc.

 

Central Processing Unit (CPU)

CPU is the component that actually responsible for interpreting and executing most of the commands from the computer hardware and software and also controls the operation of all other components such as memory unit, input and output devices. It simply accepts binary data as input and processes data according to those instructions and provides the result as output. It is the logic machine. So, its main function is run the program by fetching instructions from the RAM, evaluating and executing them in sequence. In summary, the function of CPU are as follow:

• Read instruction from memory
• Communicate with all peripherals using the system bus.
• It controls the sequence of instructions.
• It controls the flow of data from one component to another component.
• Performs the computing task specified in the program.

The CPU has three components responsible for different function, these components are Control units, arithmetic-logical unit (ALU) and Register.

fig(components of cpu)

Control Unit

The control unit provides the necessary timing and control signals to all the operations on the computer. It controls the flow of data between the CPU, memory and peripherals. It also controls the entire operation of a computer. It obtains the instructions from the program stored in the main memory, interprets the instructions and issues the signals, which cause the other units of the system to execute them. So, it is considered as a central nervous system of a computer that provides status, control and timing signals necessary for the operation of other parts of CPU, memory and I/O devices. The main functions of control units are given below:

• It performs the data processing operations with the aid of program prepared by the user and send control signals to various parts of the computer system.
• It gives commands to transfer data from the input devices to the memory to an arithmetic logic unit.
• It also transfers the results from ALU to the memory and then to the output devices.
• It stores a program in the memory.
• It fetches the required instruction from the main storage and decode each instruction and hence execute them in sequence.

Arithmetic Logic Unit

This is the area of CPU where various computing functions are performed on data. The ALU performs arithmetic operations such as addition, subtraction, multiplication and division and logical operation such as comparison AND, OR and Exclusive OR. The result of an operation is stored in Accumulator or in some register. The main functions of ALU are as follow:

• It accepts operands from registers.
• It performs arithmetic and logic operations.
• It returns a result to register or a memory.

The logical operations of ALU give the computer the decision-making ability.

 

Registers

Registers are the high-speed temporary storage locations in the CPU made from electronic devices such as transistors, flip-flops, etc. So, registers can be thought as CPU’s working memory. Register are primarily used to store data temporarily during the execution of a program and are accessible to the user through instructions. These are the part of Control unit and ALU rather than of memory. Hence, their contents can be handled much faster than the contents of memory. Although the number of registers varies from computer to computer. There are some registers which are common to all computers. Five registers that are essential for instruction execution are:

• Program Counter (PC): Contains the address of the next instruction to be fetched.
• Instruction Register (IR): Contains the instruction most recently fetched.
• Memory Address registers (MAR): Contain the address of a location in memory for read and write operation.
• Memory Buffer Register (MBR): It contains the value to be stored in memory or the last value read from memory.
• Accumulator (ACC): An accumulator is a general purpose register used for storing temporary result and result produced by the arithmetic logic unit.

 

Output Unit

The output unit is formed by the output devices attached to the computer. Output devices are used to present result produced by the computer to the users. The output from the computer is in the form electric signals, which is then converted into human understandable form into human readable form.

The examples of output devices are the monitor, printer and speaker.

The main functions of the output unit are as follow:

• Accepts the result produced by the computer which is in electric binary signals.
• It then converts the result into human readable form.
• Finally, it supplied the converted results to the outside word.

 

We can also discuss some of the categories of a computer system. Some of the categories of computer system are:

• Hardware
• Software
• Data or information
• Procedure (data which the computer converts)
• User
• Communication

1. Hardware

Hardware refers to the part of the computer which we can touch. It is the physical devices of the computer. It consists of interconnected electronic equipment that controls everything the computer does. It includes input devices, input devices, output devices, processing devices and storage devices. Example of hardware are keyboard, monitor, CPU, hard disk and RAM.

2. Software

The software is the term used to describe the instruction that tells the hardware, what and how to perform a task. Without software, the hardware is useless. Examples of software are Window 7, MS office, Internet explorer, etc.

3. Data/Information

The function of a computer system is to convert data into information. Data can be considered as the raw facts whether in a paper, electronic or the other form that is processed by the computer. In other words , data consist of the raw facts and figures that are processed to form information. Information is summarized data or manipulated or processed data.

4. People

People constitute the most important parts of the computer system. People operate the computer hardware and create the computer software. They also follow a certain procedure when using the hardware and software.

5. Procedure

The procedure is a description of how things are done, step for accomplishing a result. Procedure for a computer system appears in documentation manual, also known as reference manual which contains instruction, rules, and guidelines to follow when using hardware and software. When you buy a microcomputer or software package, it comes with one or more documentation manuals.

6. Communication

When one computer system is set up to share data and information electronically with another computer system, communication becomes a system element. In other words, the manner on which the various individual system are connected by wires, cables, phone lines, microwave, Wi-Fi or satellite is an element of the total computer system.

CLASSIFICATION OFCOMPUTER ON THE BASIS OF SIZE

1. Super Computer
2. Mainframe Computer
3. Mini Computer
4. Micro Computer

1) Super Computer

Super computer is one of the most powerful computers which is used to perform the complex calculations. They are the fastest computer which works in nanosecond even in a picosecond too. This computer is used for a special purpose. Usually, such computer uses parallel processors. Nowadays, the computing capability of a super computer is equal to that of 40,000 micro computers. Mostly super computers are used by government agencies. These computers are used in research and other operations where there is a huge numerical calculation. Different industries also use this huge computer for designing their products. It is also used in Hollywood movies for animation purposes. It requires large space and temperature control room. CRAY X-MP/24, NEC-500, PARAM, etc are some of the examples of a super computer. Today's super computers are designed by companies such as HP, IBM, Cray Inc.

2) Mainframe computers

Mainframe computers are powerful multi-user computers capable of supporting many hundreds of users simultaneously. It is also large in size. This computer has slower processing speed than a super computer but faster than a mini and micro computer. It is designed for large-scale data processing and a huge amount of data storage. They are used in a big organization such as bank, insurance companies, airlines, railway reservation system, e-mail service providers, web hosting, etc. It needed a large area approximately 1000 sq.ft. It supports a large number of I/O terminals, more than 100 terminals.

 

In a mainframe, each user accesses the mainframe’s resources through a device called a terminal. Their terminals are attached to the mainframes to perform the different types of task in FIFO.

Dumb terminal and intelligent terminal are the two kinds of terminals. A dumb terminal is the input/output device that functions as a window into a computer located somewhere else. An intelligent terminal can perform some processing operations, but it usually does not have any storage.

IBM 1401, ICL 2950/10,CYBER 170, etc are some of the examples of mainframe computers.

3) Minicomputer

Minicomputer is also a multi-user computer capable of supporting ten to hundreds of users simultaneously. Due to the smaller size and its cost compared to mainframe and a super computer, it got its name as a minicomputer. It is also known as midrange computer. Minicomputer can handle more input and output than a micro computer. It can support about 50 terminals and requires an area around 100 sq ft. This computer is useful for medium sized business, organizations, industries, universities and banks. It is cheap and easy to operate than a mainframe computer.

Prime 9755, VAX 7500, HCL, MAGNUM, CDC-1700, etc. are some of the examples of a mini computer.

4) Microcomputer

A computer which is based on a microprocessor is called microcomputer. They are small and single user computer. This computer has a keyboard for entering data, a monitor for displaying and a storage device for storing the data. It requires less area compared to other computers.

This computer consists of central processing unit and a single chip. It is mainly used in office, school, house, shop, etc.The smallest of this category are a laptop, notebook, palmtop and PDA. IBM PC, Apple/Macintosh, etc. are the examples of the microcomputer. The microcomputer is categorized as a non-portable and portable category.

Some of the examples of microcomputer are described below:

• Desktop

  • The desktop computer is the kind of personal computer (PC), which is a common type of computer used by many people today. They are a non-portable computer.

    The term “desktop computer” means the concept of such a computer actually sitting on top of a desk. A computer is known as “workstation” is actually a relatively powerful kind of desktop.

    This type of desktop has a faster processor, more memory and other advanced features compared to another desktop. Common desktops often have much computing capability compare to the workstation.

• Laptop

  • A ‘laptop’ computer is a light, compact and portable PC. It contains a rechargeable battery. They also contain a built-in LCD monitor. It is a portable computer.

    To make them as portable as possible; most laptops try to avoid any sort of cable or wire. In laptop, instead of a mouse, a trackpad is used. Instead of wired connection to a network or printer, ‘wireless’ radio connection are used.

    A laptop is also known as a notebook, which is another kind of personal computer used by many people today. It has usually a flat-screen monitor and keyboard attached to the computer.

    Most of the laptop have a clam-shell case design, which means that the case opens in a way similar to a clam. Some of the laptops are in the form of a tablet.

• Handheld

  • A handheld computer is a kind of portable computer that is intended to be held and used in a hand. A handheld computer is becoming more and more common in modern society.

    This computer includes various kinds of PDA (Personal Digital Assistant) computers, such as those running palm OS or windows mobile. Nowadays, mobile phones have slowly replaced by smartphones and similar handhelds with mobile phone capabilities.

    Those phones which contains the running of Google Android, windows mobile and also the iPhone are the handheld computer which has the function of mobile phones.

 

 

 

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