Computer Fundamentals
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  • 1. 1. GENERATIONS OF COMPUTERS:The tem generation indicates the type of technology used in thecomputer construction. As new technology was emerging, it wasbeing used in the making of computer. The new technology improvedthe speed, accuracy and storage capacity of the computers.Different technologies have been used for computers in differenttimes.Therefore, computers can be divided into five generationsdepending upon the technologies used. These are:First Generation (1942 – 1955)Second Generation (1955 – 1964)Third Generation (1964 – 1975)Fourth Generation (Since 1975)Fifth Generation (Since 1980)1. First Generation Computers (1942 – 1955):The vacuum tube technology was used in first-generationcomputers. Mark-1m, ENIAC, EDSAC, EDVAC, UNIVAC-1 etc.machines belong to the first generation of computers. The machinelanguage only was used in first-generation computers.Principle:-The vacuum tubes consisted of filaments inside it which on heatingemit electrons. These electrons were responsible for theamplification and deamplification of electrical signals.Input:-Punched cardsOutput:-Print-outsAdvantages:
  • 2. *These computers were the fastest of their time.*They were programmed using machine language.*The electronic digital computers were introduced due to thevacuum tube technology.Disadvantages:*Very large in size*Not reliable*Consumed large amount of energy*Constant maintenance required*More heat generated and air-conditioning was required*More costly*Very slow in speed (data processing)*It was difficult to programmed, because they used only machinelanguage*Non-portable*Limited commercial use2. Second Generation Computers (1955 – 1964):The transistor technology was used in second-generationcomputers. The electronic component transistor was invented in1948 at Bell Laboratories. The transistor is smaller in size andmore reliable than vacuum tube. Therefore, the transistortechnology was used in computer in place of vacuum tubetechnology. The programming assembly language was also introducedin second-generation of computers.The transistors consisted of BASE, COLLECTOR and EMITTER.Their functions include:-BASE: input gate for the transistor.COLLECTOR: collect the amplified signalsEMITTER: output gate for emitting the amplified signals to theexternal environment.
  • 3. Advantages:*Low in cost*Smaller in size*Fast in speed*Less heat generated more reliable and accurate in calculations*Consume low power etc.*Used for commercial purposes*Portable*Assembly language was introduced. This language is easy to writeprogram than machine languageDisadvantages:*Air-conditioning required*Commercial production was difficult and these were very costly*Constant (or frequent) maintenance required*Only used for special purposes3. Third Generation Computers (1964 – 1975):The IC (Integrated Circuits) technology was used in third-generation computers. In a small IC chip (5 mm square size) acircuit is designed having large number of electronic componentslike transistors, capacitors, diodes, resistors etc. Initially, an ICcontained only about ten to twenty components. Thus the ICtechnology was named as Small Scale Integration (SSI). The third-generation was based on IC technology and the computers weredesigned using this technology.Advantages:*Smaller in size*Production cost was low*Very fast in computational power
  • 4. *More reliable*Low power consumption*Maintenance cost was low because failure rate of hardware wasvery low*Magnetic disk, used for external storage*More storage capacity*Easily portable*Easy to operate*Upgraded easily*Widely used for various commercial applications all over the world*Lower heat generated*High-level languages were commonly used*Many input/output devices were introduced such as mouse andkeyboard etc.Disadvantages:*Air-conditioning required*Highly sophisticated technology required for the manufacturerchips4. Fourth Generation Computers (1975 onwards):The microchip technology was introduced in this generation ofcomputers. With the advancement in IC technology, LSI (LargeScale Integration) chips were developed. It was possible tointegrate over 30,000 or more components on to single LSI chip.After LSI, the VLSI (Very Large Scale Integration) was developedand the development of microprocessor possible. It is expectedthat more than one million components will be integrated on a singlechip of VLSI. Using VLSI technology, the entire CPU is designed ona single silicon chip. The use of microprocessor as CPU introducedanother class of computers called the microcomputers. Thusfourth-generation may be called Microcomputer generation. IBM
  • 5. introduced its personal computer for use in 1981.Advantages:*Smaller in size*Production cost is very low*Very reliable*Hardware failure is negligible*Easily portable because of their small size*Totally general purpose*Air conditioning is not compulsory*Very high processing speed*Very large internal and external storage capacity*Used advanced input & output devices such as optical readers,laser printers, CD-ROM/DVD-ROM drives etc.Disadvantages:*Highly sophisticated technology required for the manufacturer ofmicroprocessor chips5. Fifth Generation Computers (In process):The main drawback of first to fourth generation computers is thatthe computers have not their own thinking power. These are totallydepending upon the instructions given by the users.Fifth generation computers are supposed to be the ideal computers,but do not exist. The scientists are working to design suchcomputers that will have the following features.*Having their own thinking power*Making decisions themselves*Having capabilities of learning*Having capabilities of reasoning*Having large capacity of internal storage
  • 6. *Having extra high processing speed*Having capabilities of parallel processingTechnologies used in fifth generation computers:*ULSIC (Ultra Large Scale Integrated Circuits) technology*Artificial Intelligence (AI) technology also called the knowledgeProcessor. The AI means automatic programs that let the machinesto think and decide themselves. The programming languages LISP(List Processor) and PROLOG (Programming with Logic) are used forartificial intelligence. The scientists at ICOT in Japan use thePROLOG to develop the Artificial Intelligence software.Advantages:*Laptops, Pocket computers and PDA were developed.*Development of parallel processors*Development of centralized servers*Development of optical disc technology*Invention of internet and its advantages.2. CLASSIFICATION OF COMPUTERS:Computers can be classified based on the following criteria:According to Technology: $Analog Computers $Digital Computers $Hybrid ComputersAccording to Purpose: $General purpose Computers $Special ComputersAccording to size: $Supercomputers
  • 7. $Mainframe Computers$Minicomputers$Microcomputers, or Personal ComputersBased on operating principles and technology:Analog computers:$These computers represent data in the form of continuouselectrical signals.$These are fast and multi-tasked.$Results displayed by these computers are less accurate.$Powerful in solving differential equations.$These computers use OP-AMP (Operational Amplifier).$The features of OP-AMP include: *High voltage gain. The voltage gain is defined as the ratio ofoutput voltage to input voltage. *Infinite input resistance. The input resistance is defined as theratio of change in input voltage to the change in input current. *Zero output resistance. The output resistance is defined as thenominal resistance measured with nil loads.$The basic OP-AMP circuit is represented as:Wherein, Rin is the input resistance, RF is the feedback resistanceA is the amplifier which is used to invert the incoming signals of
  • 8. voltage Vin to Vout.Digital computers:$These are called the Digital information processing systems.$These systems store and process the data in digital form (stringsof 0s and 1s)$They are capable of processing analog signals but the analogsignals have to be converted into digital signals using an ADCbefore feeding into the digital computers.Hardware components:$Arithmetic Logical unit (ALU)$Control unit$Memory unit$Input unit$I/O unitsHybrid computers:$These are the combination of both Analog and Digital computersencompassing the best features of both the computers.$Fast, efficient and reliable computer systems.$The Data is measured and processed in the form of electricalsignals and stored with digital components.$The input is accepted in the form of varying electrical signals andis converted into discrete values for performing operations.$They are used in hospitals to measure heartbeat and haveengineering and scientific applications.Based on Applications:General purpose computers:$Work in all environments$Versatile computers$Store number of programs to perform distinct operations
  • 9. $More expensive$Not efficient and consume large time to generate resultsSpecial purpose computers:$Work on specific tasks$Non-versatile$Speed and memory of these computers depend on the taskperformed$More efficient and consumes less time to process results$Less expensiveBased on size and capability:Micro-computers:$These are small cheap digital computers for individualsHardware components:Microprocessor, storage unit, I/O channels, power supply,connecting cables.Software components:Operating System (OS), Utility software, Device driversAvailable in the forms of:PCs, Work stations, Notebook computers.The various components are:Microprocessors:$This incorporates all functions of the CPU into a single unit. Thevarious units of microprocessor are:$ALU: performs arithmetic and logical operations.$Registers: Store data and instructions temporarily needed by theALU.It includes several types like: Accumulator (ACC), ProgramCounter (PC), etc.$CU: Control unit-Used to manage and control the functions ofmicroprocessors, I/O devices
  • 10. $Memory:Used to store data and instructions. It is of two types: *Primary memory: It stores temporarily the data and instructionsneeded by the microprocessor *Secondary memory: It stores data permanently. Examples includemagnetic tapes, floppy, CD, USB, etc,Peripheral devices: $Input devices: They are used to transfer data into thecomputer. Examples: keyboard, mouse, etc, $Output devices: Used to display the results processed by thecomputer. Examples: Monitor, printer, etc,System bus:$It is also called the FRONTSIDE BUS, MEMORY BUS, LOCAL orHOST BUS.$It is used to connect microprocessor, memory and peripheraldevices into a unit. SYSTEM BUS= ADDRESS BUS+DATA BUS+CONTROL BUS$Address bus: Unidirectional bus to identify the peripheral devicesand memory.$Data bus: Bi-directional bus used to transfer data among themicroprocessor, peripheral devices and memory.$Control bus: bus used by the microprocessor to send control
  • 11. signals to various devices.Depending on size, Microcomputers are of three types:*Desktop computers:They are used in single location, cheap, and have good storage.Examples include: Apple, IBM.*Laptop computers:Portable computers also called as the notebook computers or mobilecomputers. They are smaller in size, more expensive and arerechargable.Examples include Apple, Acer, Hewlett Packard (HP)*Hand-held computers:Also called as Personal Digital Assistants (PDAs), Palmtop orMobile device. They are smaller in size, have smaller display andinput device is generally an electronic stylus. Their storagecapacity is small. Examples include Apple Newton, Franklin eBookman.Mini computers:$These were introduced by Digital Equipment Corporation (DEC) in1960.$They can process more data and can support more I/O devicesThey are less powerful than mainframe computers but morepowerful than micro computers. Hence they are called MID-RANGECOMPUTERS.They cater to the needs of 4-200 users at a time$They are used in business as a centralized computer or as aninternet server$They are less expensive than Mainframe computers. Examplesinclude PDP 11, IBM 8000 series, etc,Mainframe computers:$These are capable of handling millions of records a day.$These are bigger and more expensive than mini-computers
  • 12. $They require a large space and closely monitored humidity andtemperature.Characteristics: *A typical mainframe computer consists of 16 microprocessors andeven more than that. *RAM capacity is 128MB to 8GB *They can run multiple operating systems. Hence they are called-VIRTUAL MACHINES *They handle a large amount of I/O devices which are arranged inseparate CABINETS or FREMES and hence the name.Applications: *they are used in large financial transactions *Enterprise Resource Planning (ERP) *Industry and consumer statistics *CensusSupercomputers:$These are the fastest and complex computers with very highspeed$First Supercomputer was presented by SEYMOUR CRAY in 1960 inControl Data Corporation (CDC)$Used exclusively in applications where large complex calculationshave to be performed to get the output$These are very expensive and designed to perform only smallnumber of programs at a time$The manufacturers of Supercomputers are: IBM, SILICONGRAPHICS, FUJSTU, INTEL, etc.These are the fastest as they employ 1000s of processors, 100’sof GB of RAM, 1000’s of GB of secondary storage$the principles used in these computers are: *Pipelining: This enables the processor to execute secondinstruction even before the first is completed provided, it has therequired resources
  • 13. *Parallelism: Enables the processor to execute several instructionsat a time$Examples include: CRAY 3, Cyber-205, PARAM, etc.3. Characteristics of computers:Computers have distinguishing characters which make them idealmachines. But they do not certain characters which human possess.Some of the important characteristics of computers are:(I)Automatic:#Computers are automatic machines which once started a job,carry it on until it is complete provided they are given the requiredinstructions by the users.(II)Speed:#The computers are capable of taking logical decissions,performing arithmetic and non-arithmetic operations on alphabetsand copying at an unbelievable speed#The units of speed for a computer are in microseconds (10 -6) oreven in nano and Pico second (10 -9 or 10 -12)#A powerful computer can perform 3 to 4 million arithmeticoperations per second#The speed of the computers is attributed to the fact that THECOMPUTERS ARE ELECTRONIC DEVICES WORKING ONELECTRICAL PULSES WHICH TRAVEL AT HIGH SPEED.(III)Accuracy:#The computer produces highly accurate and reliable results#The errors in the calculations may be due to the error in thelogic of the human but not due to the computer.#The computers perform accurate calculations n number of times(IV)Versatility:#A computer is capable of performing a wide variety of functions
  • 14. #It can accept data and produce results.#It can perform the basic arithmetic and logic operations#It can transfer data internally#Several applications can be run at a time. For example MS paintAdobe Photoshop and VLC media player can be run at a time.(V)Diligence:#A computer is capable of performing the same task over and overagain with the same degree of accuracy and reliability as the firstone#This is because, unlike human beings, computers are free frommonotony, tiredness, lack of concentration, etc, and can workhours together without creating bugs.(VI)Large and perfect memory:#A computer can store and recall any amount of informationbecause of its secondary storage capability with perfect accuracyunlike human beings.#The storage capacity of the computer is enormous and is perfect#A computer recalls a data with greater accuracy even afterseveral times and does not lose any information unless it isprompted to do so.(VII)No I.Q and feelings:#A computer is not intelligent on its own and cannot think on itsown#It can only perform the tasks specified by the human but thedifference is that it does this with greater accuracy and speed.#It cannot decide on its own and only the user can determine whatthe computer must do#A computer has no feelings but a human does.4. Basic computer organization:
  • 15. The organization of computers involves the interfacing of variouscomponents of the computer and the co-ordination of theoperations performed by them. The various functional units of acomputer include:(I)Input unit(II)Memory unit(III)Central processing unit(IV)Output unitBASIC COMPUTER ORGANISATIONInput devices:@These devices are used to feed the data inside the computer.@The most commonly used input devices are:*keyboard*mouse
  • 16. *light pen*digitizer*trackball*joystick*OCR (Optical Character Recognizer)*MICR (Magnetic Ink Character Recognizer)*OMR (Optical Mark recognizer)Keyboard:@It is used to enter alphanumeric data into the computer and toperform special functions:@Alphanumeric keys: Used to enter alphabets and Numbers@Function keys: Used to perform special functions. These includeF1 to F12.For example F5 is used for refreshing a page or desktop@Modifier keys: SHIFT and CONTROL keys are called modifierkeys and they perform special functions. For example CTRL+X forcut@Spacebar key: Used to move by one space in a document orworksheet or DBMS.@Enter key: Used to open something like a file or a web-page orto move to the succeeding line in a document.
  • 17. Mouse:@It is an electronic device used for selecting and pointingpurposes. Hence it is called the POINTING DEVICE.@Left mouse button: Used for selection purpose@Right mouse button: Used to perform special functions like OPEN,EXPLORE, COMPRESS, etc.@Ball at the bottom: The ball at the bottom of the mouse movesand the cursor moves on the screen in whichever direction the ballrotates@Wheel at the top: To scroll a web-page or a document.Scanner:@Used to scan images and documents@The scanned images are converted into the DIGITISED IMAGESunderstandable by the computers.@Color images can also be scanned using the scanner dependingupon the RED GREEN BLUE (RGB) PROPORTIONS@The principle used in the BARCODE READER is similar to that ofa scanner.Memory unit:
  • 18. MEMORY PYRAMID OF A COMPUTERThe memory unit is used to store data on a temporary orpermanent basis. The various types of memory can be depicted as: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
  • 19. MEMORY:PRIMARY MEMORY
  • 20. @Read only memory *MASK PROM *PROM *EPROM *EEPROM@Read/Write memory *Static RAM *Dynamic RAM *Cache memorySECONDARY MEMORY@Disk Drives *Floppy *Hard disk *CD-ROM (Read only and Rewritable)@Tape drives: *Cartridge Drive *Cassette driveINTERNAL PROCESSOR MEMORY@Registers *ACC *PC
  • 21. *IR *MAR *MBR *MDRPrimary memory:@This memory is also called as MAIN MEMORY.@The information stored in this memory that are needed by themicroprocessor during the time of processing are temporary andthe information in the ROM are permanentRead Only Memory (ROM):@It is a non-volatile memory@The contents of this memory are permanent@These are cost-effective@They are available in high storage capacity@Processing speed is very low@Generally, the OS supporting programmes and the Basic InputOutput System (BIOS) programs are stored in this@In this trigonometric and logarithmic functions are also stored@In PROM (Programmable Read Only Memory), The flexibility ofdata alteration is also provided.
  • 22. Random Access Memory (RAM):@This is the part of computers temporary storage where the ALLTHE DATA, INSTRUCTIONS NEEDED BY THE MICROPROCESSORAND THE RESULTS EXECUTED BY IT are stored.@It is a volatile memory@The contents are temporary@Cost is very high@They are available in small storage capacity@processing speed is high@User defined programmes can be stored at any timePrinciple:-Each bit in a RAM stores information by means ofelectric charge, where the presence of electrical signals indicate1and the absence of electrical signals indicate0.Types of RAM:DYNAMIC RAM:@The electric charges tend to be leak out in a few milliseconds, sothe information present in RAM is lost@Hence, the set of data stored in Dynamic ram has to berefreshed periodically before all the charges have leaked.STATIC RAM:
  • 23. @Special refresh circuitry is provided@They are not leaky and hence do not require any refreshingCache memory:A small memory between the CPU and the main memory is calledthe cache memory.@It is faster than main memory and the access time of thismemory is close to the processing speed of the CPU@It acts as a HIGH-SPEED BUFFER between the CPU and themain memoryIt is used to store temporary and active (most frequently used)data during the time of processingThe other components of primary memory include:@PROM (Programmable Read Only Memory)@EPROM (Erasable PROM)@EEPROM (Electrically Erasable PROM)Secondary memory:@The secondary memory is also called as the AUXILLARYMEMORY@It may be in-built or may be introduced into the computer and is
  • 24. used to store the data on a PERMANENT basis@The various types of secondary memory include:Magnetic storage device:@Use magnetism property to store data@The data stored in these devices can be stored, erased,rewritten many number of times@Examples include: Magnetic tapes, magnetic disks, floppy disk,etcOptical storage device:@Uses the LASER BEAMS to store data@The data stored in these devices can be erased and rewrittenmany number of times@Examples include: CD, CD-ROM-CD-RW, DVD, etc.Magneto-Optical storage device:@This uses both MAGNETISM and LASER BEAMS to store data@These devices are generally used in the cases of BACKUP, DATARECOVERY, etc,@The data stored in the can be erased and rewritten many times
  • 25. CU (CONTROL UNIT) ALU (ARITHMETIC LOGICAL UNIT) Universal Serial Bus (USB): @These are commonly called as pen drives @These are compact and store large data than the other storage devices @These are connected to the USB PORT in the CPU Central processing unit: The CPU is the main functional unit of the computer. The basic functions of CPU include: @fetch the data from the user @Decode the data into a computer-understandable form @Process the data or execute the operation @Store the result This sequence of functions is called the INSTRUCTION CYCLE and is represented as:
  • 26. MAIN MEMORY EXECUTEFETCHThe various units of the CPU include:ARITHMETIC LOGICAL UNIT (ALU):@It is used to perform the various arithmetic and logicaloperations.@Arithmetic operations like +,-,*, / are performed by ALU@Logical operations like >, <, =, =/= are performed by the ALUwith the help of logical gates like NOT, OR, AND, etc.@The three basic concepts of the ALU include:@Opcodes: The data on which the operation is to be executed@Operands: The operations to be performed on the data@Format code: The format in which the data is represented, For
  • 27. example like, STATIONARY POINT OR FLOATING Pointed, etcCONTROL UNIT (CU):@The CU control the flow of information@It is called THE BRAIN OF THE CPU@It directs the tasks performed by the ALU and also thefunctions carried out by the I/O DEVICESREGISTERS:@The CPU contains certain temporary storage units called as theREGISRES.@The various types of registers and their functions are:@Program Counter (PC): Stores the next operation to be performed@Information Counter(IC): Store the information or data to beprocessed by the CPU@Memory Address Register (MAR): Stores the address of the nextlocation in the memory@Memory Buffer Register: Stores the data received from or sentto the CPU@Memory Data Register (MDR): Stores Operands and DataOutput units:
  • 28. @These are electronic or electromechanical devices which give thedesired result or output to the user in the USER-UNDERSTANDABLE format.@The various output units include:*Visual Display Unit (VDU) or Monitor*Printer*Computer Output Micro file*PlotterMonitor:@The monitor is a visual display unit used to display the output tothe user and is often referred to as the ELECTRONIC MEDIAPrinciple:-When the beams of electrons in the electrical signalsstrike the inner side of the monitor containing RED, BLUE andGREEN PHOSPHOROUS, the color and detail of the object isvisible depending on the PROPORTIONS OF THE COLOR and theINTENSITY OF THE ELECTRON BEAMS@The types of monitor include: Cathode Ray Tube (CRT) and LiquidCrystal Display (LCD)@Cathode ray is better at picture perception when compared toLCD
  • 29. @The CRITICAL PARAMETERS of the monitor include:*SIZE (length, breadth, thickness)*RESOLUTIONS (pixels)@Video card is to be installed for better graphical perceptionPrinter:@printer is used to get a printed or PHOTOCOPY of the documentor image present in the system.@The types of printers include:@DOTMATRIX PRINTERS: High speed printers but the quality ofthe image is poor@INKJET PRINTERS: Slower than the Dot-Matrix printers buthave good picture quality@LASER PRINTERS: Since these printers have their own ROM,RAM and MICROPROCESSOR and hence produce HIGH QUALITYIMAGES WITH GOOD SPEED.Quality of printers is measured using the CRITICAL PARAMETERS:*DOT PER INCHES (DPI)*PAGES PER MINUTE (PPM)Speaker:@It is an electromechanical device that converts ELECTRICAL
  • 30. SIGNALS into SOUND WAVES@AUDIO DEVICE DRIVER has to be installed for the speaker toperform@Speaker may be in-built or it may be separately attached to thecomputer@Quality of the speaker is dependent on the SOUND CARDinstalled in the computer@Sophisticated Speakers contain SUB-WOOFER SYSTEM toincrease the BASS OUTPUT5. MEMORY UNIT OF THE COMPUTER AND VARIOUS TYPES OFMEMORY (REFER MEMORY UNIT IN THE ORGANISATION OFCOMPUTERS)6. EVOLUTION OF COMPUTERS: • In earlier years, people used fingers, stones, pebbles, and notches in sticks and knots in ropes to perform simple arithmetic calculations. • SAND TABLE:(EARLIER PERIOD)  Used stones for calculations  It contains three channels filled with sand and each chamber can hold a maximum of 10 stones • ABACUS:(2500 BC)  It was invented by ASIA MINOR in 2500 BC.
  • 31.  It consisted of a wooden frame with strings and beads which were used for calculations.• NAPIER’S BONE:(1614)  This is a complicated manual device calculated by JOHN NAPIER in 1614  This device consisted of a board with nine rods  The rod on the left corner consisted of digits from 1 to 9  The rod at the extreme right consisted of ZEROS and was called the CONSTANT ROD  It was exclusively used for multiplying or dividing two numbers only if one of the numbers is a single digit• SLIDE RULE:(1620)  It was devised by EDMUND GUNTER in 1620  It consisted of two graduated scales sliding over each other  It was used to perform not only simple arithmetics, but also complex calculations like LOGARITHM and TRIGNOMETRIC ROOTS, etc.• PASCALINE:(1642)  It was devised by BLAISE PASCAL in 1642  It was also called as the ROTATING WHEEL CALCULATOR or NUMERICAL WHEEL CALCULATOR  It was designed to handle numbers up to 999,999.999• STEPPED RECKONER:(1694)  Pascaline was improved by a German mathematician, GOTFRIED WILHELM VON LEIBNIZ into a stepped reckoner  It performs multiplication, division and also SQUARE ROOT of a number• DIFFERENCE ENGINE:(1822)  It was devised by CHARLES BABBAGE in 1882
  • 32.  It used the features of the modern digital computers like INPUT,OUTPUT,STORAGE,PROCESSOR and CONTROL UNITS  It was designed to perform mathematical calculations by getting two inputs from the user(a)a set of programs that contains the instructions to be executed(b)a list of variables on which the operation is to be performed  It was a digital automatic programmable general purpose computer  Its disadvantage was that it was a slow engine taking 3 minutes to multiply 2 numbers of 20 digits each• 1883-The idea of analytical difference engine was given by CHARLES BABBAGE• 1889-The idea of punched cards as input was introduced by HERMAN HOLERITH• MARK-I(1994):  It was devised by Aiken,an American mathematician in 1937 and completed in 1994  It is faster than difference engine. For example, it can multiply two digits of 20 digits each within 6 seconds  But it was slow in processing the results(RATE OF RESULT=ONE RESULT/SECOND)  It was noisy and large in size• COLOSSUS(1994):  It was devised by ALAN MATHINSON, a British mathematician in 1994  It was a pure electronic digital programmable computer  It used VACUUM TUBE TECHNOLOGY
  • 33.  It was designed to perform only specific operations• ENIAC(1946):  Electronic Numerical Integrator And Calculator developed by John Eckert and John Mauchley in 1946  Used Vacuum tube technology for basic circuits  Consisted of 17468 vacuum tubes, 7200 crystal diodes, 10000 capacitors, 1000 relays  1000 times faster than MARK-I  Perform simple arithmetic and advanced operations  Used DECIMAL SYSTEM for representing and processing values• EDVAC(1949):  Electronic Discrete Variable Automatic Computer devised by Eckert and Mauchley in 1949  Worked on the principles of STORED PROGRAMS(program and data are considered as strings of BINARY DIGITS)  Units are: Magnetic tape, Control unit, Dispatcher unit, Processor, Timer, Dual memory, Three temporary tanks to hold a single word• EDSAC(1949):  Electrical Delay Storage Automatic Calculator developed by Maurice Wilkes in 1949  Vacuum tube technology used for basic circuits and MERCURY DELAY LINES for memory construction  Input unit- Punched cards  Output unit- Teleprinter  Able to carry out 650 instructions per second• UNIVAC(1951):  Universal Automatic Computer developed by ECKERT-MAUCHLEY corporation in 1951  5200 Vacuum tubes were used for basic logic
  • 34. circuits and MERCURY DATA LINES for memory construction It can process numbers and alphabets Since it provided separate processors for handling input, output and processing units, it was UNIQUE among the early computers