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MIS: Computers, Dr. Ashish K. Gupta


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This is a basic presentation on the history and components of computers for the beginners in the field

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MIS: Computers, Dr. Ashish K. Gupta

  1. 1. 8/10/2013 1 Computers Dr. Ashish K. GuptaDr. Ashish K. Gupta MBBS, MS-Surgery, PGDHHM, MBA-HCA (FMS) Gold Medalist, MAHA, PG in Quality Management & AHO, Consultant Surgeon, Hospital Consultant, NABH-Assessor, CMD Blue Ocean Consultants Director Programs AHA Study Objectives: 1. History 2. Computers- Structure & Functions 3. Computer Functions 1. Processing data 2. Data Storage 3. Data Movement: 4. Control Mechanism: 4. Computer Subunits 1. Central Processing Unit CPU 2. Main Memory 3. Input Output Units 4. Interconnections 5. Computer Speed 6. Gates & Memory Cells 7. Microchip Speed 8. Microchip 9. CPU 10. Main Memory 11. Secondary Memory 12. Input Output Devices Saturday, August 10, 2013 2 (Study Duration= 1 Hour) History • Computers have brought about a revolution in the field of computing as a result of technological advancement in the field of electronics • ‘Abacus’ the first mathematical devices used to facilitate arithmetical computation was invented by the ancient Chinese before the birth of Christ • Abacus used beads strung of wires & is even today in use Saturday, August 10, 2013 3 First Mechanical Computer • Also KA ‘Analytical Engine’ • Designed by Charles Babbage • Between 1830 & 1850 marked the birth of computer age • It was able to perform basic arithmetical functions Saturday, August 10, 2013 4 Five components of Charles Babbage’s Analytical Engine • A store to hold numbers • An arithmetic unit (which he called the ‘Mill’) to perform arithmetical operations • A control unit to control & coordinate various activities in the correct sequence • An input device to transfer both numbers & instructions into the computer • An output device to display the results of computation Saturday, August 10, 2013 5 Remarkably.. • Even today’s computers are built around the same concepts • Modern computers however provide three major advantages: – Enabling the computer to operate at electronic speed (an electron travels 1 foot in I billionth of a second – Providing tremendous reliability – Making the computer a general purpose machine Saturday, August 10, 2013 6
  2. 2. 8/10/2013 2 History Contd.. • The first computer was KA UNIVAC (Universal Automatic Computer) using vacuum tube circuits & was used by the US Census Bureau in 1951. this belonged to the First Generation of Computers • Invention of transistor by Bell Labs USA gave birth to Second Generation Computers which used transistors instead of vacuum tubes. IBM 1401 • Third generation computers introduced in mid 1960s with the invention of tiny integrated circuits on silicon chips. IBM released its 360 series computers • Computers with large scale ICs became available in 1969 & were KA fourth generation computers. But there is no general agreement on what constitutes a Fourth Generation Computer Saturday, August 10, 2013 7 History Contd.. • Invention of the micro-processor in 1972 changed the computing scene dramatically • A Microprocessor when integrated with memory & input/ output units became a micro-computer • Micro-computer is very small in size, at the same time is very powerful & provides a user friendly atmosphere for users to interact with it • The first business microcomputer KA APPLE 11 was released in USA in 1977 Saturday, August 10, 2013 8 History Contd.. • Recent advances in the field of artificial intelligence are being used to design a ‘thinking computer’ • It has been tried to infuse intelligence into the computers • These are KA Fifth generation computers • A special feature anticipated in these computers is their ability to respond to spoken words Saturday, August 10, 2013 9 ComputersComputers-- Structure & FunctionsStructure & Functions • Structure & functions of computers are simple • A computer is expected to perform four operations: – Data processing – Data storage – Data movement – Control Saturday, August 10, 2013 10 ComputerComputer FunctionsFunctions Saturday, August 10, 2013 11 Data Movement Control Mechanism Data Processing Data storage Computer FunctionsComputer Functions 1. Processing data: From the point of view of a user this data may take a variety of forms & the range of processing requirements are very broad, but fundamentally within the computer there are very few types of data processing 2. Data Storage: Essential for a computer. Even when the processing is being done on the fly & the results are being generated as the data is being fed, there is some form of temporary storage required. Storage requirements are therefore for short & long term Saturday, August 10, 2013 12
  3. 3. 8/10/2013 3 Computer FunctionsComputer Functions 3. Data Movement: From outside world & manipulated data back to the outside world. The movement of data can be both to the devices directly attached to the computer i.e. peripherals or to the remote devices. The form of movement is KA Input, Output & when to the remote devices, data communications Saturday, August 10, 2013 13 Computer FunctionsComputer Functions 4. Control Mechanism: All of the above requires some measure of control. Computers run several programs at the same time, for many users at the same time. Inputs from one user must be segregated from the inputs of others & ditto for the outputs. This control is exercised by the instructions supplied by the users of the computers themselves. Within the computer there is a control unit that manages the resources & aligns the functioning of various parts in accordance with these instructions Saturday, August 10, 2013 14 Computer Subunits: HardwareComputer Subunits: Hardware Corresponding to these functions there are sub- units within a computer to accomplish these. They are; 1. Central Processing Unit CPU 2. Main Memory 3. Input Output Units 4. Interconnections Saturday, August 10, 2013 15 ComputerComputer SubunitsSubunits Saturday, August 10, 2013 16 Input/ Output Inter connections Central Processing Unit Main Memory Computer Computer SpeedComputer Speed • We have seen that computers have been increasingly becoming faster & cheaper • Obvious questions are: – What is the speed of a computer? – How is it related to the size of the computer? • The four functions of data processing, data movement, data storage & data control inside a digital computer are provided by only two fundamental structures: – Gates & – Memory cells, interconnected to each other Saturday, August 10, 2013 17 Gates & Memory CellsGates & Memory Cells • These are constructed out of simple electronic components like: – Resistors – Capacitors etc. – These are now fabricated on a single silicon chip – Small scale integration combines thousands of these components at a time & today a very large scale integration can combine millions of these components on a single chip Saturday, August 10, 2013 18
  4. 4. 8/10/2013 4 Gates & Memory CellsGates & Memory Cells This means: • Gates & memory elements can be placed much closer to each other reducing the time electrical impulses to travel hence increasing speed • More & more gates & memory can be placed in the same space increasing speed for the same size • There is a reduction in power & cooling requirements • The computer becomes smaller • The interconnections become more & more reliable Saturday, August 10, 2013 19 Microchip SpeedMicrochip Speed • Microchips work with an arrangement of clock speed or frequency, in one cycle they execute one operation • Speed is measured in hertz, i.e. cycles per second Saturday, August 10, 2013 20 1 Kilo Hertz= 10 3 Hertz 1000 Hertz 1 Mega Hertz= 103 Kilo Hertz 1000000 Hertz 1 Giga Hertz= 103 Mega Hertz 1000000000 Hertz MicrochipMicrochip • Microchip is the brain behind the computer • Processing unit works along the Main Memory & Input Output Unit to perform tasks that we see computers performing • The processing unit is also KA Central Processing Unit CPU Saturday, August 10, 2013 21 CPUCPU • CPU is the most important component of a computer’s hardware & has an arithmetic logic unit (ALU) & a control unit • ALU performs all the arithmetical (+, x, ÷) & logical (Is A=B? Is a given character equal to M for Male & F for Female?) operations • All arithmetic & logical operations are performed in the CPU in a special storage area called registers • The size of register is a very important consideration in determining the speed of processing • Register size means the amount of information that can be held by the register at a time for processing- Larger the Faster Saturday, August 10, 2013 22 CPU Contd..CPU Contd.. • CPU’s processing power is measured in million instructions per second (MIPS) • Speed of CPU was measured in – Milliseconds (1/1000th of a second) on first generation computers – Micro-seconds on second generation computers (one millionth of a second) – Nano-seconds on third & fourth generation computers (one billionth of a second) – It is expected to be measured in pico-seconds (one 1000th of a nano- second) in near future fifth generation computers. Saturday, August 10, 2013 23 Architecture of Computer HardwareArchitecture of Computer Hardware Saturday, August 10, 2013 24 Input Device Output Device Control Unit ALU e.g. Keyboard, Mouse, Mike, Camera, Scanner, CD/DVD Rom CPU e.g. Printer, Display Screen, Speakers,
  5. 5. 8/10/2013 5 CPU: Control UnitCPU: Control Unit • Control unit in CPU controls & coordinates all operations of a CPU • It ensures that required information is transferred between main memory, ALU, Input devices & Output devices in required & desired sequence • It also contains logic circuits & storage needed for control of multiple input output devices • When a program begins an input operation, control unit identifies the input devices & sets up electronic data path for the data & instructions to enter CPU • Subsequently control unit executes various operations in CPU in desired manner • Upon completion of job, control unit identifies the required output devices & sets up data paths for supplying the output informationto the desired output devices Saturday, August 10, 2013 25 Main Memory (MM)Main Memory (MM) • MM stores a variety of critical information required for processing by CPU How does it store information? • A computer works on electricity • A binary number system that uses only two digits, namely 0 & 1 is a convenient way to represent information • 1 represents presence of an electric impulse & 0 represents its absence • Information in a computer consists of data (numerical & non- numerical) & instructions that are made up of large number of characters like decimal numbers 0 to 9, alphabets A to Z, arithmetic operations +, -, x, ÷ etc., relational operators etc. & many special characters like (, . ? “ ; :) etc. Saturday, August 10, 2013 26 Main MemoryMain Memory • With two binary digits we can represent four different characters (00, 01, 11) • With three digits we can represent eight different characters (000, 100, 010, 001, 110, 011, 101, 111) • Computers use eight binary digits (bits) to represent informationinternally, allowing up to 256256 different characters • A collection of eight bits is called a byte • One byte is used to represent or store one character internally • Most computers use 2 or 4 bytes to represent numbers (positive & negative) internally Saturday, August 10, 2013 27 Main MemoryMain Memory • Memory unit stores all information in memory cells, KA memory locations, in binary digits • Each memory location has a unique address • Contents of a memory location are provided to the central processing unit by referring to the address of the memory location • The amount of information that can be held in the main memory is KA Memory capacity • This capacity is measured in Kilobytes (KB) • 1 KB stands for 103 which are approximately 1000 bytes • A mega byte stands for 106 which are approximately one million bytes or 1000 KB Saturday, August 10, 2013 28 Main MemoryMain Memory • Earlier computers used magnetic core memory • Modern computers use semi-conductor memory, which is faster & cheaper than magnetic core memory • Semi-conductor memory is also available in a small board • This has made SC Memory more popular & attractive • Only drawback of SC memory is that it is volatile i.e. it loses its contents in the event of power failure. However this is not a serious drawback & is overcome by back-up power • SC memory is also KA RAM (Random Access Memory) • RA means that any part of the memory can be accessed for reading & writing • RAM capacity is a useful indicator to compare the main memory capacity of various computers Saturday, August 10, 2013 29 Main MemoryMain Memory • Another part of main memory is ROM (Read Only Memory) • ROM allows its contents to be read only, a does not allow users to store their programs • Usually ROM contains utility programs supplied by manufacturers Saturday, August 10, 2013 30
  6. 6. 8/10/2013 6 Secondary MemorySecondary Memory • SM is essential to any computer due to its limited MM • Three types of SM available: 1. Serial access memory: This provides only a serial access to retrieve information stored in it 2. Random access memory: Provides a random access to retrieve information stored in it 3. Index sequential method: The file here is accessed by certain tables that divide the file into definite areas. The read/ write head is taken to the beginning of the concerned area & therefore the file is accessed sequentially • Like a cassette tape provides serial access & LP record providing a random access memory • Computers use magnetic tapes to provide serial access memory & magnetic discs to provide random access memory Saturday, August 10, 2013 31 Input & Output DevicesInput & Output Devices • The input or output units of a computer system establishes the communication between the system & its users. • A large number of input output devices are available. • Few devices are: – Punched card: Most ancient input medium. A card reader is reqd. – Terminals: Very popular input, output units. Directly connected to CPU is used to send in information & extract information either as a print on a paper (Hard copy terminal) or on a display screen (Soft copy terminal) – Key-to-tape, key-to-disk & key-to-diskette: are stand alone data entry stations and are convenient to use – A graphic display terminal: Displays information in both character & graphic forms. These are extensively used for CAD/CAM (Computer Aided Design/ Manufacture) applications Saturday, August 10, 2013 32 Input & Output DevicesInput & Output Devices – A plotter: Is used to obtain printed copies of graphic outputs. Used by architects & designers – Printers: Popular output devices. Classified as line printers, dot printers. Line printer prints one line at a time while the dot matrix printer prints one character at one time – Daisy Wheel printers & Letter Quality Printers: These are also character printers, but they produce excellent quality output. Very expensive & slow – All the printers discussed above are impact printers as they make physical contact with the paper while printing; a non impact printer transfers information to paper without any physical contact. E.g. Laser printers, Xerographic printers, Electrostatic printers Saturday, August 10, 2013 33 Input & Output DevicesInput & Output Devices • Source data automation: This is the recent trend for data input. The equipments used for source data automation capture data as a by-product of a business activity thereby completely eliminating manual input of data – Magnetic Ink Character Recognition: Used by banking system to read account numbers on cheques directly & to do necessary processing – Optical Mark Recognition Devices: Can sense marks on computer readable paper. Used in academic & testing institutions to grade aptitude tests wher candidates mark the answers on a special sheet of paper that are directly read by the optical mark recognition devices; Another example if Bar Code Reader. Saturday, August 10, 2013 34 Questions? Saturday, August 10, 2013 35