COS 101: Introduction to Computing

Brief History of Computing

• The computer has a profound impact on our lives, and its development is a long process
• The development of computers can be divided into three directions: miniaturization, speed, and affordability

Early History of Computing

• Abacus (2500 BC): the first known calculating machine used for counting, addition, and subtraction
• Slide Rule (1633 AD): invented by William Oughtred, used for multiplication and division by method of addition and subtraction
• Napier's Bones (1614 AD): invented by John Napier, used for multiplication and division by reducing complexity to simpler operations
• Rotating Wheel Calculator (1642 AD): developed by Blaise Pascal, a predecessor to today's electronic calculator

20th Century Devices

• Differential Analyzer (1920s-1930s): developed by Vannerver Bush, an analog computer that solved differential equations
• Harvard Mark 1 (1944): developed by Howard Aiken, an electromechanical machine that was the world's first computer
• ENIAC (1946): developed by John W. Mauchly, the first general-purpose electronic computer that used vacuum tubes
• EDSAC (1949): developed by Mauchly and J. Presper Eckert, a binary electronic computer that used stored-program concept
• UNIVAC (1951): developed by Eckert and Mauchly, the first commercial computer that handled numbers and alphabet characters

Generations of Computers

• First Generation (1937-1953): used vacuum tubes, large, expensive, and unreliable
  • Features: vacuum tube components, large in size, consumed a lot of energy, generated a lot of heat
  • Examples: abacus, Pascaline, UNIVAC, ENIAC, EDVAC
• Second Generation (1954-1962): used transistors, smaller, faster, and more reliable
  • Features: transistor components, smaller in size, consumed less energy, generated less heat, supported machine and assembly languages
  • Examples: IBM 1620, TADIC, IBM 704, IBM 7030, IBM 7094
• Third Generation (1963-1972): used integrated circuits, even smaller, faster, and more reliable
  • Features: integrated circuit components, even smaller in size, consumed less energy, generated less heat, supported high-level languages
  • Examples: IBM-360 series, Honeywell-6000 series, PDP, IBM-370/168, TDC-316
• Fourth Generation (1972-1984): used large-scale integrated circuits and very large-scale integrated circuits
  • Features: microprocessor components, very small in size, very cheap, easily available, portable, and reliable
  • Examples: DEC 10, STAR 1000, PDP 1, CRAY-11, CRAY-X-MP, APPLE 1, IBM PC, MACINTOSH
• Fifth Generation (1983-1990): based on parallel processing hardware and artificial intelligence software
  • Features: ultra-large-scale integration technology, artificial intelligence, natural language processing, parallel processing
  • Examples: IBM PC-AT, Intel 80486, video toaster
• Sixth Generation (1990-till date): marked by gradual improvements over established systems
  • Features: World Wide Web, HTML, Web TV, DVD, YouTube, and many more
  • Examples: Power Book by Apple, Pentium microprocessors by Intel, Sun Ultra workstation

What is a Computer?

• A computer is an electronic device that can: accept data, process data according to specified rules, provide information in a useful format, and store results for future use

• It is an automatic machine capable of processing data and producing information### Information and Computers

• Information is data that is processed and presented in an organized manner.

• Examples of information include names of students in alphabetical order, total and average marks calculated and presented in a tabular form.

Computer Functionalities

• A computer works as an Input-Process-Output (IPO) system.
• The five functions of a computer are:
  • Input: taking data as input and command from the input device to the computer.
  • Processing: converting input data into required output form with the help of computer program and hardware.
  • Output: generating output which is displayed by the computer to the user, either in hard copy or soft copy.
  • Storage: storing data/instructions in its memory and using them as required inside or outside the computer.
  • Control: controlling all the above four steps.

Advantages of Computers

• High speed: computers can perform millions of calculations in a few seconds.
• Accuracy: computers perform thousands of operations with 100% accuracy provided the input is correct.
• Storage capability: computers have much more storage capacity than human beings.
• Diligence: computers can perform jobs for a long time obediently, free from monotony, tiredness, and lack of concentration.
• Versatility: computers can be used to solve multiple tasks in various domains at the same time.
• Reliability: computers do exactly what they are told to do without human intervention.
• Automation: computers can perform a given task automatically under the control of a stored program.
• Communication: computers can connect to share resources.
• Power: the larger the word length of a computer, the more powerful it becomes.
• Paperless processing: data can be processed using computers instead of papers.

Disadvantages of Computers

• No IQ: a computer cannot take any decision on its own.
• No self-correction: a computer cannot correct any wrong instruction fed in by an operator.
• Dependency: a computer functions only when programmed; thus, it is fully dependent on humans.
• No decision-making: a computer cannot decide how it is to be programmed or provide input.
• No feeling: computers have no feelings or emotions and so cannot make judgments based on feeling, taste, experience, and knowledge.

Computer Hardware Components

• A computer is made up of two constituents: hardware and software.
• The term hardware refers to all the physical devices, or components, that a computer is made of.
• A computer is not one single device, but a system of devices that all work together.
• The five major categories of hardware components are:
  • Processing devices
  • Secondary storage devices
  • Input devices
  • Main memory
  • Output devices

Processing Devices

• The processing unit consists of the central processing unit (CPU), arithmetic logic unit (ALU), control unit, and main memory.
• The CPU is the part of a computer that runs programs.
• ALU is where all arithmetic operations and logical functions are performed.
• The main memory stores data, program instructions, internal results, and final output temporarily before it is sent to an appropriate output device.

Input Devices

• Input devices collect data and send it to the computer.
• Examples of input devices include:
  • Keyboard
  • Mouse
  • Scanner
  • Microphone
  • Digital camera
  • Bar code reader
  • Light pen
  • Touch sensitive screen
  • Magnetic ink character recognition (MICR)
  • Magnetic reader
  • Optical character recognition (OCR)
  • Optical mark reading and recognition (OMR)
  • Smart cards
  • Notes taker
  • Microphone

Output Devices

• Output devices present information from a computer.
• Examples of output devices include:
  • Monitors
  • Printers
  • Disk drives
  • CD recorders
  • Speakers
  • Plotters
  • Projectors

Monitors

• A monitor is a commonly used output device.
• Monitors provide a visual display of data.
• Types of monitors include:
  • CRT monitor
  • LCD monitor
  • Laptop screen

Printers

• A printer is an output device that prints text or images on paper or other media.
• Types of printers include:
  • Impact printers
  • Non-impact printers
  • Line printers
  • Dot matrix printers
  • Thermal printers
  • Laser printers
  • Inkjet printers### Storage Devices
• Secondary storage is a type of memory that can hold data for long periods, even when there is no power to the computer.
• Secondary storage devices:
  • Magnetic tapes
  • Floppy disks
  • Hard disks
  • Optical disks (e.g. CD, DVD, Blu-ray)
• Characteristics of secondary storage devices:
  • Access time: the time required to reach a storage location and obtain its contents
  • Hard disk:
    • Magnetic disk with high-speed rotating surfaces
    • Data is arranged in concentric rings (tracks) and sectors
    • Read and write heads are combined into a single head unit
    • Smallest unit that can be written to or read from the disk is a sector
  • Magnetic tape:
    • A recording medium consisting of a thin tape with a magnetic coating
    • Data is stored in frames across the width of the tape
    • Frames are grouped into blocks or records separated by gaps
  • Floppy disk:
    • A thin circular disk for data storage
    • Rotates at 360 rpm
    • Data is recorded in tracks and sectors
    • Can be write-protected
  • Optical disk:
    • A storage medium from which data is read and written using lasers
    • Random access storage medium
    • CD-ROM stands for Compact Disk - Read-Only Memory

Computer Software

• Software refers to various kinds of programs used to operate computers and related devices.
• Categories of software:
  • System software:
    • Operate, control, and extend the processing capabilities of the computer
    • Provide an environment to run application programs
    • Examples: operating system, translators, utility programs
  • Application software:
    • Designed to solve a user problem in a particular area
    • Examples: word processing, spreadsheet, database management

Operating System (OS)

• An integrated set of specialized programs that manage the overall operations of a computer.
• Primary goals of the OS:
  • Optimize resources
  • Provide a user-friendly environment
• Functions of the OS:
  • Process management
  • Memory management
  • Device (I/O) management
  • File management
  • Job scheduling
  • Interpretation of commands and instructions
  • Monitoring performance
  • Security management

Application Software

• General-purpose application programs:
  • Developed to suit the needs of research workers/scientists in different fields
  • Examples: word processor, spreadsheet, database management system, graphics
• Word processing software:
  • Enables creating, editing, formatting, storing, and printing text and graphics
  • Examples: Microsoft Word, WordStar, WordPerfect
• Spreadsheet software:
  • Computer equivalent of a paper worksheet to organize numeric data
  • Examples: Lotus 1-2-3, Corel's QuattroPro, MS Excel

Database Applications

• A collection of related information about a particular subject stored in a way that can easily be accessed, managed, and updated.
• Examples: computerized banking system, automated teller machine, airlines, and railway reservation system
• Database management systems:
  • MS-Access
  • ORACLE
  • MySQL

Types of Computer

• Classification of computers based on size, speed, and computing power:
  • Microcomputers
  • Minicomputers
  • Mainframe computers
  • Supercomputers
• Microcomputers:
  • Smallest range of computers with less storing space and processing speed
  • Examples: personal computers, workstations, desktops, laptops, PDAs
• Workstations:
  • Desktop computers used for engineering or graphic applications
  • Characteristics: high processor speed, high-resolution graphics screen, large amount of RAM, inbuilt network support, graphical user interface