Study Material and Notes of Chapter 1 Computer and its components Computer Science Class 10th
• Computers were initially developed to perform mathematical operations but later on, they were used to store the result of those operations, which with the time leads to the storage of other data or information
• Data is a collection of unprocessed facts, figures, and symbols. For example: Ram, age, 32, years, old.
• Information is a processed form of data. It is organized, meaningful, and useful. For example: Ram is 32 years old.
• Definition: A computer is an advanced electronic device that takes raw data as input from the user and gives the result by processing the data using a set of instructions. The result can be used immediately or saved for future use.
Hardware and Software
• Hardware is any part of the computer that has a physical structure that can be seen and touched, though some may be so tiny that they are invisible to the naked eye.
→ Input devices, output devices, a system unit, storage devices, and communication devices are all components of computer hardware.
• Software is the instruction set that tells the computer how to perform tasks. It is intangible i.e., that cannot be seen and touched, but its effect is clearly defined.
Components of Hardware are:
• Input devices are the devices that allow a user to enter data and instructions into a computer such as keyboard, mouse, microphone, scanner, trackball, joystick, graphics tablet and digital camera.
Various functions of input devices:
→ They accept data and instructions from the user.
→ They convert these instructions and data from human readable form to machine readable form.
→ They supply the converted instructions and data to the CPU for further processing.
• Output devices are used to display the result or information to the user through monitor
or VDUs, LCDs, printers, plotters and speakers.
Various functions of output devices:
→ It accepts the results produced by the computer which is in the coded form or machine
readable form.
→ It converts these coded results into human readable form.
→ It supplies the converted results to the user.
Storage Devices
• Storage devices are the devices which are used to retrieved from and saved to the data and information such as hard drives, memory sticks (pen drives), compact discs, DVDs and tape drives.
• Floppy disks: These were developed in late 1960s. A floppy disk is made up of a circular thin plastic jacket coated with magnetic material. Its outer cover which is a hard plastic protects this plastic disk. It can hold 1.44 MB data. Nowadays, these disks are outdated.
• Hard Disk is made up of a metal disk and coated with a metal oxide used to store bulk of data. These disks can store more information than floppy disks, up to tens or hundreds of gigabytes.
• Compact disk read only Memory or CD-ROM is a read only or read-write disk. It can store large amount of data which can be distributed to large number of users. It is inexpensive and fast, but its access time is longer than that of magnetic disk.
There are two types of CDs:
→ CD-R stands for Compact Disk – Recordable which can store 700 MB of data, but only once.
→ CD-RW stands for Compact Disk – ReWriteable which can read, write and erase data as many times.
• DVD short for Digital Versatile Disc, is an optical storage disc similar to CD-ROM, as this is double sided with dual layer disc and can hold 4.7 GB of data.
• Blue-Ray Disks are used to store more than 25 GB of data with a very high speed in less amount of time.
• USB stands for Universal Serial Bus. It is a portable memory device which is used to store data that needs to be transferred to the other device using USB port of the system.
• Memory Card or flash memory card is used as an easy, fast and reliable medium to store and transfer data from one device to the other. It is used in digital cameras, game consoles, mobile phones etc.
CPU (Central Processing Unit)
• The system unit is the box that protects the internal electronic components from damage. It contains the central processing unit (CPU) and memory.
• The CPU interprets and carries out the basic instructions that operate the computer.
• CPU consists of the arithmetic and logic unit (alu) which executes most computer operations (arithmetic and logical) and the Control unit which acts as the nerve centre that sends control signal to all other units.
Memory
• There are two categories of memory:
→ Primary Memory is very fast as data and programs must be in the primary memory for execution. Random Access Memory (RAM) and Read Only Memory (ROM) are both primary memory.
♠ Random Access Memory refers to memory that can be selected and used randomly. The information stored here disappears the very moment the machine is turned off. It is also referred to as volatile memory.
→ Input devices, output devices, a system unit, storage devices, and communication devices are all components of computer hardware.
• Software is the instruction set that tells the computer how to perform tasks. It is intangible i.e., that cannot be seen and touched, but its effect is clearly defined.
Components of Hardware are:
• Input devices are the devices that allow a user to enter data and instructions into a computer such as keyboard, mouse, microphone, scanner, trackball, joystick, graphics tablet and digital camera.
Various functions of input devices:
→ They accept data and instructions from the user.
→ They convert these instructions and data from human readable form to machine readable form.
→ They supply the converted instructions and data to the CPU for further processing.
• Output devices are used to display the result or information to the user through monitor
or VDUs, LCDs, printers, plotters and speakers.
Various functions of output devices:
→ It accepts the results produced by the computer which is in the coded form or machine
readable form.
→ It converts these coded results into human readable form.
→ It supplies the converted results to the user.
Storage Devices
• Storage devices are the devices which are used to retrieved from and saved to the data and information such as hard drives, memory sticks (pen drives), compact discs, DVDs and tape drives.
• Floppy disks: These were developed in late 1960s. A floppy disk is made up of a circular thin plastic jacket coated with magnetic material. Its outer cover which is a hard plastic protects this plastic disk. It can hold 1.44 MB data. Nowadays, these disks are outdated.
• Hard Disk is made up of a metal disk and coated with a metal oxide used to store bulk of data. These disks can store more information than floppy disks, up to tens or hundreds of gigabytes.
• Compact disk read only Memory or CD-ROM is a read only or read-write disk. It can store large amount of data which can be distributed to large number of users. It is inexpensive and fast, but its access time is longer than that of magnetic disk.
There are two types of CDs:
→ CD-R stands for Compact Disk – Recordable which can store 700 MB of data, but only once.
→ CD-RW stands for Compact Disk – ReWriteable which can read, write and erase data as many times.
• DVD short for Digital Versatile Disc, is an optical storage disc similar to CD-ROM, as this is double sided with dual layer disc and can hold 4.7 GB of data.
• Blue-Ray Disks are used to store more than 25 GB of data with a very high speed in less amount of time.
• USB stands for Universal Serial Bus. It is a portable memory device which is used to store data that needs to be transferred to the other device using USB port of the system.
• Memory Card or flash memory card is used as an easy, fast and reliable medium to store and transfer data from one device to the other. It is used in digital cameras, game consoles, mobile phones etc.
CPU (Central Processing Unit)
• The system unit is the box that protects the internal electronic components from damage. It contains the central processing unit (CPU) and memory.
• The CPU interprets and carries out the basic instructions that operate the computer.
• CPU consists of the arithmetic and logic unit (alu) which executes most computer operations (arithmetic and logical) and the Control unit which acts as the nerve centre that sends control signal to all other units.
Memory
• There are two categories of memory:
→ Primary Memory is very fast as data and programs must be in the primary memory for execution. Random Access Memory (RAM) and Read Only Memory (ROM) are both primary memory.
♠ Random Access Memory refers to memory that can be selected and used randomly. The information stored here disappears the very moment the machine is turned off. It is also referred to as volatile memory.
♠ Read Only Memory is permanently built into the computer at the time of production. It permanently stores a set of instructions which instructs the computer how to work. After we switch on the computer, it uses instructions stored here to carry out a series of tasks automatically, before we can actually use the computer.
→ Secondary Memory or Auxiliary Memory: As the memory of RAM is volatile in nature so it becomes necessary to store this data for future use, somewhere else. That is why, secondary memory is used. Secondary memory is cheaper than primary memory which can store vast quantities of information.
Units of Memory
• Memory, storage, files and folder sizes are all measured in bytes.
• Computers work in the base 2 system, also called binary number system, using only the digits 0 and 1.
• A single numeric value using either 0 or 1 is called a bit.
• Bits are grouped into bytes to increase the efficiency of the computer. To describe large capacities, the terms Kilobyte (KB), megabyte (MB), gigabyte (GB), terabyte (TB) and Petabyte (PB) are used.
→ Secondary Memory or Auxiliary Memory: As the memory of RAM is volatile in nature so it becomes necessary to store this data for future use, somewhere else. That is why, secondary memory is used. Secondary memory is cheaper than primary memory which can store vast quantities of information.
Units of Memory
• Memory, storage, files and folder sizes are all measured in bytes.
• Computers work in the base 2 system, also called binary number system, using only the digits 0 and 1.
• A single numeric value using either 0 or 1 is called a bit.
• Bits are grouped into bytes to increase the efficiency of the computer. To describe large capacities, the terms Kilobyte (KB), megabyte (MB), gigabyte (GB), terabyte (TB) and Petabyte (PB) are used.
Software
• There are two primary types of softwares: Application software and Systems software.
• Application Software: It includes programs that direct the computer to carry out specific tasks. For example: To write error free documents, Word Processors are used such as OpenOffice.org Writer, MS Word etc.
→ There are some application softwares that are created to address specific needs of a group of specialized users and are, therefore, known as tailored or customized software to perform the required tasks in a specific manner. For example: Tally is used to address accounting needs.
• System software includes the programs that enable the computer’s hardware to work with and run the application software. It is the interface between user and the other programs and the computer’s hardware.
→ The operating system, also referred to as the OS, is a computer program that manages all the other programs on your computer, stores files in an organized manner, and coordinates the use of the computer hardware such as the keyboard and mouse.
→ Utility software is a form of system software. It is used to analyze, configure, optimize or maintain the computer. The various types of utility softwares are:
♠ Text editors facilitate the creation of flawless text documents. WordPad and Notepad are the commonly used text editors.
♠ Compression utilities are used to compress the selected files. It helps to save the space on the disk and to transfer heavy files on a network.
♠ Disk Fragmentation utility helps the user to arrange used and free space on the hard disk which in turn increases the processing speed of the disk.
♠ Scan disk utility checks for the problems on the hard disk such as bad sectors, viruses etc.
♠ Encryption or decryption utility is used to hide the data for secured transmission. At the source, data is encrypted and at the destination device, data is decrypted to reveal the original message. Decryption requires a secret key or password.
Computer Characteristics
• Speed: A computer computes problems much faster than a human being.
• Accuracy: With the high computation speed, computers are able to produce accurate results.
• No IQ: It is programmed to carry out tasks and performs exactly as instructed, since it has no intelligence of its own.
• Diligence: It can carry out tasks over and over again with exactly the same result every time, and it does so without tiring.
• Data Storage: Using different kinds of storage devices, it can store huge quantities of data over long periods of time.
• No Heuristics: As computer is a dumb machine, thus it never ever learns from its past experiences.
Generations of Computers
• Computers have been divided into five generations according to the development of technologies:
→ I generation (1945 – 55): Bulky, vacuum based and costly, used assembly language which was translated to machine level language for execution.
♠ These computers were used mainly for scientific calculations. Examples: ENIAC, EDSAC, EDVAC, UNIVAC.
→ II generation (1955 – 65) Smaller than vacuum based computers, but better performance-wise, used transistors instead of vacuum tubes.
♠ High level languages such as FORTRAN and COBOL were used.
♠ Punched cards continued to be used during this period.
♠ Examples: IBM 7030, Honeywell 400.
→ III generation (1965 – 75) Small Scale Integration and Medium Scale Integration technology were implemented in CPU, I/O processors etc.
♠ Faster processors with magnetic core memories that were later replaced by RAM and ROM.
♠ Database management, multi-user application, online systems like closed loop process control, airline reservation, interactive query systems, automatic industrial control, etc. emerged during this period.
♠ Examples: System 360 Mainframe from IBM, PDP-8 Mini Computer from Digital Equipment Corporation.
→ IV generation (1975 – 89) Microprocessors were introduced where complete processors and large section of main memory could be implemented in a single chip.
♠ CRT screen, laser & ink jet printers, scanners etc. were developed.
♠ LAN and WANS. C and UNIX were used.
♠ Examples: Intel’s 8088,80286,80386,80486 .., Motorola’s 68000, 68030, 68040, Apple II, CRAY I/2/X/MP etc.
→ V generation: 1989 to present Computers use extensive parallel processing, multiple pipelines, multiple processors etc.
♠ Portable notebook computers introduced.
♠ They also started using object oriented languages such as JAVA.
♠ Quantum mechanism and nanotechnology available.
♠ Examples: IBM notebooks, Pentium PCs-Pentium 1/2/3/4/Dual core/Quad core. SUN work stations, Origin 2000, PARAM 10000, IBM SP/2.
Categories of Computers
• According to how it functions, computers can be classified into three categories:
→ Analog: Computers in which continuously variable physical quantities, such as electrical potential, fluid pressure, or mechanical motion, are used to represent (analogously) the quantities in the problem to be solved are called analog computers.
→ Digital: These computers deal with data in the form of numbers.
→ Hybrid: Digital computers could not deal with very large numbers and so, a computer with characteristics of both analog and digital was created which was known as Hybrid computer.
• According to the size, computers are classified into the following categories:
→ Palmtop, better known as Personal Digital Assistants (PDAs), are small, lightweight and tightly integrated computers which usually do not have keyboards but rely on touch screen technology for user-input.
→ Laptops and notebooks are portable computers. They include a battery that provides
electrical backup for a period of time.
→ Personal computer (PC) is small in size and is designed for general use by a single
person.
→ Desktop computer is typically set up in a permanent location and is a PC that is not portable.
→ Micro-computers came into being with the invention of the micro-processor. They are not so expensive. The personal computer is a micro-computer.
→ Mini computers provide more power than micro computers in terms of speed and storage capacity. They are also less expensive. Their performance is also lower than that of mainframes.
→ Mainframe computers can also process data at very high speeds, but less than that of super computers.
→ A supercomputer is the fastest type of computer.
Applications of Computers
• Computers are used in almost all sectors.
→ In medicine and health care
→ In education and business
→ In the manufacturing and service industries
→ For science and research
Input → Proes → Output (IPO)
• Input-Process-Output cycle or IPO refers to the stages that a set of instructions undergo
to achieve the desired result.
• The information, through various input devices, is fed into the system to be processed by the CPU.
• The information is then received as output in the desired format and presented in human readable form.
Computer Ports and Cables
• PS/2 Ports: The PS/2 Ports are simple, 6-pin, low-speed serial connections commonly used to connect a keyboard and mouse.
• VGA Monitor Port: Video Graphics Array is used to connect the monitor to the computer. VGA offers images at higher resolutions. The standard VGA can produce as many as 256 colors at a time from a palette of 262,144 colors.
• Parallel Port: Printers and other devices are said to be either parallel or serial. Parallel means the device is capable of receiving more than one bit at a time (that is, it receives several bits in parallel).
• Ethernet Port: There is a built in Ethernet port on most computers to connect it to a wired network. Ethernet ports are also found on all popular broadband routers.
• S-Video Port: Short for Super-Video, a technology for transmitting video signals over a cable by dividing the video information into two separate signals: one for color (chrominance), and the other for brightness (luminance).
• USB Port: Universal Serial Bus, a protocol for transferring data to and from digital devices.
• Firewire IEEE 1394 Port: FireWire is a cabling technology for transferring data to and from digital devices at high speeds.
• Mini audio Jack: Audio connectors are used to affix cables to other audio equipment, providing electronic signal transference and grounding protection. Connectors may be plugs, jacks, or combinations, and may have an integral switch.
NCERT Solutions of Chapter 1 Computer and its components