Computer Overview

Computer Overview-ANNU SAINI

WHAT IS A COMPUTER?An electronic device that performs various tasks and operations or stores, correlates, or otherwise processes data as per the set of instructions given to it.

FUNCTIONING OF A COMPUTER

DATA vs INFORMATIONDATA IS RAW FACTS AND FIGURESFOR EXAMPLE MOHAN, 1977, A,-162.9, 752PROCESSED DATA IS CALLED INFORMATIONFOR EXAMPLE MOHAN WHOSE ROLLNO IS 1977, HAS GOT GRADE A

WHAT GOES IN IS DATA AND WHAT COMES OUT IS INFORMATIONTHE PROCESS OF TURNING DATA INTO INFORMATION IS ALSO KNOWN AS INFORMATION PROCESSING CYCLE. (IPO CYCLE) i.e it needs certain input, carries out a process and produces the output

FUNCTIONAL COMPONENTS OF A COMPUTER

BASIC STRUCTURE OF A COMPUTERInput Device:Punch card reader, Keyboard,Mouse, Scanner,Voice.Computer:CPU, Internal MemoryOutput Device:Monitor,Printer,Plotter,Modem,Disk Drive

External Storage:Floppy disk,Hard disk,Optical disk, Tape drive

BASIC COMPONENTS OF COMPUTER SYSTEMSUnderlying StructureLogical Structure of Digital ComputersSecondaryMemory

Input UnitData and instruction from the user to the computerConverts raw data into electronic form i.e binary form so that it can be understood by the computer

*The Central Processing Unit brain of a computerThe CPU contains:

Arithmetic / Logic UnitRegistersControl UnitSmall storage areasPerforms calculations and makes decisionsCoordinates processing steps

CENTRAL PROCESSING UNIT(CPU)Central Processor Unit (CPU)Coordinating all computer operationsPerforming arithmetic and logical operations on dataContains two subcomponentsArithmetic/Logic Unit (ALU)Carries on all types of calculation (Arithmetic and logical operations)Control Unit (CU)Controls the actions of the other components.

An integrated circuit (IC) that is a full central processing unit is called a microprocessor (p); a CPUs current instruction and data values are stored temporally inside the CPU in special high-speed memory location called registers.

Computer Output DevicesThe output information from the computer is in the form of electronic binary signals which needs conversion in some form which can be easily understood by human beingsi.e characters, graphical,or audio visualThis function of conversion is performed by output units

Common output methods:Printer output to paper using various types of printersComputer output microfilm (COM) microfilm generated for archive copies in small spaceVoice response units computer recognizes input, generates verbal response messages

Computer MemoryAll data flows to and from memory Divided into cells:Each has a unique addressMemory cell types:Byte stores one character of dataWord stores two or more characters of data

Types of memory

Measuring Memory

Each 0,1- is called a bit 1 Byte is 8 bits 1 Nibble is 4 bits 1 Kilobyte (KB) = 210 bytes (1024 bytes) 1 Megabyte (MB) =210 KB = 220 bytes(1024x1024) 1 Gigabyte (GB) = 210 MB= 230 bytes (1024x1024x1024) 1Terabyte(TB) = 210 GB=240 bytes 1 Petabyte(PT) = 210 TB=250 bytes

Types of MemoryROMRAMSRAMDRAMPROMEPROMEAPROMEAPROM

Main memoryA PC's main memory place (or primary storage) is fast storage space that is directly accessible by the CPU, used to store the currently executing program and immediate data. Main memory is usually much faster than mass storage devices like hard disks or optical discs, but cannot retain data without power. Thats why, it isnt suitable for long-term data storage. In PCs main memory usually called RAM (Random Access Memory).

Primary Memory It is the main or internal memory where execution takes place. It can be broadly categorized into two partsRAM (Random Access Memory)ROM (Read Only Memory)

RAMIt is known as the Read and Write memory. This memory is volatile.

Whatever information you store is temporary in nature and when you switch off the computer everything is erased.

Dynamic RAM

Dynamic Memory is often referred to as volatile memory. Data is stored within the capacitance of a transistor. The capacitor is unable to prevent the charge from slowly discharging. This would result in the loss of data. A solution to this problem is the introduction of additional circuitry which performs a 'memory refresh' by periodically restoring the charge. Dynamic memory is cheaper than Static memory and is used in larger memory systems.

Static RAM

Static memory is more expensive to produce than Dynamic memory, but because of its lower power consumption it is often used in small to medium sized systems. Static memory retains data within a cell until the data is overwritten or lost as a result of power being shut down.

ROM

It is a memory unit that performs the Read operation only and does not have a write capability.

The Binary information in the ROM is made permanent during the hardware production of the unit and it is not accessible to users to store information.

Secondary MemoryIt is the Permanent memory. The information stored is permanent in nature and it uses external storage devices like Floppy disk, Magnetic disk, CD-ROM etc.

When power is off, everything stored in memory is lostComputer files are used to store data long termFile storage devices:Magnetic tape drives, disk drives, floppy drivesOptical CD or DVD drives(Secondary Storage)

Sequential access filesUsually stored on magnetic tape drivesDirect access filesStored on Direct Access Storage Devices (DASD) - magnetic disk drives(Secondary Memory Storage)

Types of DASDFixed (hard) drives Figure 2.7 Diagram of a Magnetic Disk Drive

Types of DASDRemovable:Floppy drivesZip drivesNewest: portable DASD for PCs keychain/pen drive Figure 2.8 USB Keychain Drive

Winchester Disks

SRAM, DRAM, SDRAM, DDR,RDRAM, ..BLAM.. BLAMSRAMStatic Random Access Memorydoesnt need to be refreshed - but like all RAM, is erased when the power is OFFDRAM (Dynamic RAM) is a type of memory that is constantly refreshed or will loose its contents. SDRAM (Synchronous Dynamic RAM) designed to work with the CPU clock to work faster than DRAMDDR SDRAM (Double Data Rate SDRAM) works twice as fast as SDRAM10 ns speed5-10X slowerCPU

It will depend on the type of computer you have/or are buyingOlder systems are no always compatible with newer memory typesSometimes too much memory can cause problems with WindowsIt will depend on the applications you wish to runPhotoshop or other graphical applications require much more memory than simple word processingDo you wish to have many applications running simultaneously?So how much and what type of memory should you get?

Auxiliary Memory is cheaper/slower than Primary memory but is not erased when the Power Supply is OFF.Hard drive A non-removable device 20-250GB rangesFloppy disk drive- 1.44MBCDs & DVDs 600 MB. (Read vs. RW)Removable Hard drives Zip, JazzMemory Sticks To save data for later use we can store data on Secondary (Auxiliary) Memory devices

Hardware and Software

Hardware represents the physical and tangible components of the computer i.e the components that can be seen and touched. Example CPU, floppy disk, hard disk , input devices, output devices etcPeripherals are the devices that surround the system unitExample keyboard, mouse, speakers, printers, monitors etc are peripherals

A computer consists of five primary hardware components

Input devicesOutput devicesCPUStorage devicesMemoryThese components work together with software to perform calculations, organize data and communicate with other components

Software represents the set of programs that govern the operation of a computer system and make the hardware run.Its three categories are: Operating System Language Processors Application SoftwareSOFTWARESystem Software

OPERATING SYSTEM

An Operating System?What is an Operating System?A program that acts as an intermediary between a user of a computer and the computer hardware.What is the purpose of an operating system?To provide an environment in which a user can execute programs.What are the goals of an Operating System?The primary goal of an Operating System is to make the computer system convenient to use.The secondary goal is to make the computer system efficient to use.

Computer System ComponentsHardware provides basic computing resources (CPU, memory, I/O devices).Operating system controls and coordinates the use of the hardware among the various application programs for the various users.Applications programs define the ways in which the system resources are used to solve the computing problems of the users (compilers, database systems, video games, business programs).Users (people, machines, other computers).

ROLE OF OPERATING SYSTEM

OPERATING SYSTEM PERFORMS THE FOLLOWING FUNCTIONSProvides the instructions to prepare user-interface i.e way to interact with user whether through typed commands or through graphical symbolsLoads necessary programs into RAM which are required for proper functioningCoordinates how programs work with the CPU, Keyboard, mouse,printer and other hardware as well with other softwareManages the information is stored on and retrieved from disks.

Types of OSSingle UserMultiuserBatch ProcessingMultiprocessingReal TimeSupports single userCan support many usersProcesses the group of processesCan handle many CPUs at same timeBound to dead lines

LANGUAGE PROCESSORSCONVERTS HIGH LEVEL LANGUAGE INTO MACHINE LANGUAGE SO AS TO MAKE IT UNDERSTANDABLE TO THE COMPUTER

TYPES OF LANGUAGE PROCESSORSASSEMBLERINTERPRETERCOMPILER

Assembler converts the program written in assembly language into machine language

Interpreter converts HLL program into machine language by converting and executing it line by line.

Compiler converts the entire HLL program in one go, and reports all the errors of the program along with the line numbers

APPLICATION SOFTWAREAn Application software is the set of programs necessary to carry out operations for a specified application

TYPES OF APPLICATION SOFTWARECustomised Application SoftwareIt is developed to meet all the requirements specified by the userGeneral Application SoftwareIt is developed keeping in mind the general requirements for carrying out a specific task

Applications SoftwareComputer programs written to perform specified tasks. They work in tandem with specific Operating SystemsWord ProcessingSpreadsheets Database Management SystemsWeb design softwareInternet Access & E-mailGraphics Packages

STRENGTHS AND WEAKNESSES OF A COMPUTERSTRENGTHSSpeedHigh Storage CapacityAccuracyReliability (immune to fatigue & boredom)Versatility (can perform repetitive jobs efficiently)WEAKNESSESLack of decision makingIQ Zero

EVOLUTION OF COMPUTERSTHE CONCEPT OF A COMPUTER DID NOT MATERIALIZE OVERNIGHT.

LET US LOOK AT THE DEVELOPMENT OF THE COMPUTER THROUGH VARIOUS STAGES

ABACUSAn ABACUS consists of beads divided into two parts which are movable on the rods of the two parts

NAPIER LOGS AND BONESJohn Napier developed the idea of logarithm.He used logs to transform multiplication problem to addition problemThis device later became the basis for a SLIDE RULENapier also devised set of numbering rods known as Napier Bones.

PASCALS ADDING MACHINEBlaise Pascal, French mathematician invented a machine in 1642 made up of gears which was used for adding and subtracting numbers quickly. This machine was called ADDING MACHINEit worked on clock work mechanism

LEIBNITZS CALCULATORGotfried leibnitz, a German mathematician ,improved on ADDING MACHINE and constructed a machine in 1671 that was able to perform multiplication and division.

JACQUARDS LOOMJOSEPH JACQUARD manufactured punched cards at the end of American Evolution to control looms in 1801.The entire process was automatic and under a programs control.With the invention of punched cards the era of storing and retrieving information started that greatly effected later inventions.

BABBAGES DIFFERENCE ENGINECharles Babbage developed a machine called Difference Engine in 1822. It was expected to calculate logarithmic tables to a higher degree of precision.It was made to calculate various mathematical functions

BABBAGES ANALYTICAL ENGINEThis device becomes real ancestor of the modern day computerIt was capable of performing all four arithmetic operations as well as comparison.It included the concept of central processor, storage area, memory and input-output devices in his design.

HOLLERITHS MACHINEHerman Hollerith, an American fabricated the dream of Charles Babbage. This machine was used by American Department of Census to compile their data .And were able to complete compilation in 3 years which earlier used to take around 10 years.

Mark-IProf. Howard Aiken in U.S.A. constructed in 1943 an electromechanical computer named Mark-I It could multiply two 10 digit number in 5 seconds. It was the 1st machine which could perform according to pre programmed instructions automatically without manual interference. This was the first operational general purpose computer.

The Generation of Modern ComputerThe term computer Generation is used in relation to the hardware of computers. Each phase of computer development is known as separate generation of computers. Each phase of development is characterized by type of switching circuits it utilizes.

Stored Program ComputerMost computers today use the idea of stored program computer that was proposed by Dr. John Von Neumann in 1945. The Van Neumann architecture is based on three key concepts.

Von Neumann ArchitectureData & instructions are stored in a single read-write memory.The memory contents are addressable by locations.Execution takes place in a sequential fashion i.e. from one instruction to the next unless modified explicitly.

The First Generation Computers (1949-55)

Key Features of First Generation ComputersUsed vacuum tubesBig and clumsy computersElectricity consumption highElectric failure occurred regularlyLarge air conditioners were necessary (computers generated heat)Programming in machine language

Examples of First Generation ComputersENIACEDVACEDSACUNIVAC-I

The Second Generation Computers(1956-65)

Key Features of Second Generation ComputersTransistor replaced vaccum tubesComputer became smallGenerated less heatElectricity consumption lowerMore reliableFasterFirst operating systems usedProgramming in machine language as well as assembly languageCore memory developedMagnetic tapes and disks used.

Examples of Second Generation ComputersIBM 1401IBM 1620IBM 7094CDC 1604CDC 3600UNIVAC 1108

The Third Generation Computers(1966-75)

Key Features of Third Generation ComputersIntegrated circuits developedComputers smaller, faster and more reliablePower consumption lowerHigh level languages appeared

Examples of Third Generation ComputersIBM-360 SERIESICL-1900 SERIESIBM-370/168ICL-2900HONEYWELL MODEL 316HONEYWELL 6000 SERIESSOME MINI COMPUTERS DEVELOPED DURING THIS PHASE AREICL-2903 BY INTERNATIONAL COMPUTERS LIMITEDCDC-1700 BY CONTROL DATA CORPORATIONPDP-11/45 BY PERSONAL DATA PROCESSOR

THIRD GENERATION COMPUTERS ARE USED IN THE FOLLOWING AREASEDUCATIONSURVEYSMALL BUSINESSESESTIMATIONANALYSIS ETC ALONG WITH THEIR PREVIUS USAGE AREAS I.E SCIENTIFIC AND ENGINEERING

THE FOURTH GENERATION COMPUTERS(1976- PRESENT)

Types of Computers

1. PC

The personal computer (PC) defines a computer designed for general use by a single person. While a Mac is a PC, most people relate the term with systems that run the Windows operating system. PCs were first known as microcomputers because they were a complete computer but built on a smaller scale than the huge systems in use by most businesses.

2. Desktop

A PC that is not designed for portability is a desktop computer. The expectation with desktop systems are that you will set the computer up in a permanent location. Most desktops offer more power, storage and versatility for less cost than their portable brethren. http://www.paramounttraining.com.au/storage/ComputerWorkshop.jpg

3. LaptopAlso called notebooks, laptops are portable computers that integrate the display, keyboard, a pointing device or trackball, processor, memory and hard drive all in a battery-operated package slightly larger than an average hardcover book. http://blog.loaz.com/media/blogs/timwang/mini-laptop-fujitsu-P7230.jpg

4. PDAPersonal Digital Assistants (PDAs) are tightly integrated computers that often use flash memory instead of a hard drive for storage. These computers usually do not have keyboards but rely on touchscreen technology for user input. PDAs are typically smaller than a paperback novel, very lightweight with a reasonable battery life. A slightly larger and heavier version of the PDA is the handheld computer. http://sartechnology.ca/sartechnology/PDA6.jpg

5. Work Station The fifth type of computer is a workstation. A workstation is simply a desktop computer that has a more powerful processor, additional memory and enhanced capabilities for performing a special group of task, such as 3D Graphics or game development.

6. Server A computer that has been optimized to provide services to other computers over a network. Servers usually have powerful processors, lots of memory and large hard drives. The next type of computer can fill an entire room.

http://farm3.static.flickr.com/2369/2084311380_0906fd827d_o.jpg

7. Mainframe In the early days of computing, mainframes were huge computers that could fill an entire room or even a whole floor! As the size of computers has diminished while the power has increased, the term mainframe has fallen out of use in favor of enterprise server. You'll still hear the term used, particularly in large companies to describe the huge machines processing millions of transactions every day. http://www.geekzone.co.nz/images/news/IBMSystemz10mainframe.jpg

8. Mini computer Another term rarely used anymore, minicomputers fall in between microcomputers (PCs) and mainframes (enterprise servers). Minicomputers are normally referred to as mid-range servers now.

9. Super Computer This type of computer usually costs hundreds of thousands or even millions of dollars. Although some supercomputers are single computer systems, most are comprised of multiple high performance computers working in parallel as a single system. The best known supercomputers are built by Cray Supercomputers. http://huehueteotl.files.wordpress.com/2007/04/supercomputer.jpg

10. Wearable Computer The latest trend in computing is wearable computers. Essentially, common computer applications (e-mail, database, multimedia, calendar/scheduler) are integrated into watches, cell phones, visors and even clothing! For more information see these articles on computer clothing, smart watches and fabric PCs. http://gtresearchnews.gatech.edu/images/fast2_b.jpg

Optical computerscurrent research in computer architecture includes much work on the design of computers which use light beams to perform computation; these machines should be smaller, faster and cooler than current electronic machines

Biological computers computers based on DNA: problems are encoded on strands of DNA which are mixed in solution and react to form DNA-coded answers

ANALOG COMPUTERAnalog computers measure the continuous change in something Current in a wire Movement of the tide Rate at which a wheel turns 2. More complicated to build than digital computers 3. Analog computers are very rare today

DIGITAL COMPUTERSUse discrete numbers (whole digits) to control the electrical circuits Built of switches that are either on or off Can not have values in-between 0 or 1 like the analog computer 1 turns the switch on 0 turns the switch off Almost all computers built today are digital computers

First Generation - Vacuum Tubes1. From 1946 to 1956 did from 2,000 to 16,000 additions per second Had main memory 100 bytes to 2 kilobytes 2. Used vacuum tubes 3. Very large machines special rooms to house them with air conditioning specially trained technicians to run & maintain

Second Generation - Transistors

From 1959 to around 1965 Smaller, faster, and more reliable used transistors 6,000 to 3,000,000 operations/s main memory 6 kilobytes to 1.3 megabytesContained in four cabinets about 6 feet high by 4 feet wide, each weighing 250 pounds one-tenth the price of a 1st Generationbecome common in larger businesses and universities

Third Generation - Integrated Circuits

Form 1965 to around 1972 Used integrated circuits many transistors on one piece of silicon 3. Smaller, faster, more reliable, and lower in price Size of a stove or refrigerator, some can fit on desktops Can do 100,000 to 400,000,000 operations per second Cost about one-tenth the amount of second generation computers 4. Computers become very common in medium to large businesses

Fourth Generation - Microprocessors

From 1972 until now Used large scale to very large scale integrated circuits Put more than one IC on a silicon chip Can do more than one function smaller, faster, more reliable, and lower in price Size of a television or much smaller Can do 500,000 to 1,000,000,000 operations/second Cost one-tenth, or less, the amount of third generation very common in homes and business

Future Computer Generations

Most likely the following will happen to computer technology It will become lower in price Computers will become smaller and faster Computers will have larger memories and more storage space 2. Computers will become an integral part of everyone's life

COMPUTER TYPESCRITERIA OF CLASSIFICATIONHISTORYTWO BASIC KINDSGENERATIONMANUFACTURERWIDELY ACCEPTED CLASSIFICATION

WIDELY ACCEPTED WAYSSIZE (Early days): mainframe, minicomputer, microcomputer.SIZE (Now): Floortop, Desktop, Laptop, Palmtop, Wearable.POWER: Supercomputer, server, enterprise server (mainframe), mid-range server (minicomputer), PC.

PCcomputer designed for general use by a single person. PCs were first known as microcomputers because they were a complete computer but built on a smaller scale than the huge systems in use by most businesses.

DESKTOPA PC that is not designed for portability. you will set the computer up in a permanent location. Most desktops offer more power, storage and versatility for less cost than their portable brethren.

LaptopAlso called notebooks.Laptop are portable computers that integrate the display, keyboard, a pointing device or trackball, processor, memory and hard drive all in a battery-operated package slightly larger than an average hardcover book.

PalmtopMore commonly known as Personal Digital Assistants (PDAs) palmtops are tightly integrated computers that often use flash memory instead of a hard drive for storage. usually do not have keyboards but rely on touchscreen technology for user input. A slightly larger and heavier version of the palmtop is the handheld computer.

WorkstationA desktop computer that has a more powerful processor, additional memory and enhanced capabilities for performing a special group of task, such as 3D Graphics or game development.

MainframeIn the early days of computing, mainframes were huge computers that could fill an entire room or even a whole floor! the term mainframe has fallen out of use in favor of enterprise server. the term still used, particularly in large companies to describe the huge machines processing millions of transactions every day.

Minicomputerterm rarely used anymore, minicomputers fall in between microcomputers (PCs) and mainframes (enterprise servers). Minicomputers are normally referred to as mid-range servers now.

SupercomputerCosts hundreds of thousands or even millions of dollars. Most are comprised of multiple high performance computers working in parallel as a single system. Used for military purposes or in large companies

WearableThe latest trend in computing Essentially, common computer applications (e-mail, database, multimedia, calendar/scheduler) are integrated into watches, cell phones, visors and even clothing!

TYPES OF COMPUTER

What software you need will affect you decision of what hardware to buyFor example how much hard drive space will you need with the following requirements?Windows XP Professional Operating System - *1.5 GBFull install of MS Office 2003 - *450 MB Dream Weaver - *800 MB Adobes Photoshop - *280MB Have room to store my photo album with 150 pictures - .. Average of 500KB eachIn GB: 1.5+.45+.8+.28+150*.005=3.78

Hardware Development

First Generation (1946-1959)Second Generation (1960-1965)Third Generation (1966-1975)Fourth Generation (1975 - Now)Accessories

Software Development

System SoftwareOperating SystemsUtility ProgramsLanguage Translators

Operating System

Without operating system, a software application ora program language software cant communicate with the computer. Operating System is just like a brain on human body which organize all process inside a human body

There are six basic functions that an operating system can perform :

1. Schedule Jobs. 2. Manage Hardware and Software Resources 3. Maintain Systems Security 4. Enable Multiple User Resource Sharing 5. Handle Interrupts 6. Maintain Usage Records

Utility ProgramsUtilities enable users to copy files, erase files, sort the content of files, merge two or more files together, and prepare removeable storage mediafor use.Other utilities allow the computer operations manager to recover lost or bad files, monitor performance of the system, and event control the flow data between users and computers.

Language Programming :There are three different kind of Language programming: Machine Language Low level Language High Level LanguageAssemblerFortran, Lisp, Algol, Cobol,RPG, Basic, Pascal, Prolog, C,Matlab, etc.

Machine LanguageA computer's native language, containing instructions that are binary numbers.It is difficult for human to learn and use.Instructions to the control unit must be expressed in terms of the machine language of the particular computer.A machine language instruction conveys the operation to performed and the operands, or memory cells, that are to take part.

Example, compute the cost of an itemcost = price + tax

Operation CodeOperation Meaning

001Load Copy the value of the memory cell addressed into the accumulator010Store Copy the value of the accumulator into the word addressed011Add Replace the present value of the accumulator with the sum of its present value and the value of the memory cell addressed....111Halt Terminate execution Sample Instruction Set

Assembly LanguageIs programming language in English-like abbreviationsLater be converted into machine code by program's translator called assemblersExample, adds to number and store in another variableLOAD AADD BSTORE C

High-Level LanguageA programming language whose instructions resemble every day languageHas a language standard that describe the grammatical form (syntax) of the languageEvery high-level language instruction must conform to the syntax rules specified in the language standard.Example, BASIC, C, C++, COBOL, FORTRAN, LISP, PASCAL, JavaExample of C++ code, cost = price + tax;

Topic

History of computer developmentComputer generationProgramming language

History of Computer DevelopmentCharles BabbageDesign first modern computerInventdifference engineAnalytical Engine (main part of copmuter system)

History of Computer DevelopmentCount Ada LovelaceFirst programmerAssist in developing instruction for Babbage device computation

History of Computer DevelopmentHerman HollerithDevelop first computer using electrical powerFounder of electronic punch card

History of Computer DevelopmentJohn V. Atanasoff & Clifford BerryBuild first electronically operated digital computer ABC (Atanasoff Berry Computer)

History of Computer DevelopmentUNIVAC 1 (Universal Automatic Computer)First generation comercial computerFor scientific and comercial applicationsEckert & Mauchly send first UNIVAC to U.S Census Bureau in 1951.

History of Computer Development

History of Computer DevelopmentUNIVAC characteristicEasier to use compared to ENIACLess vacuum tube (more reliable)Stored program found by John Von NeumannGeneral purposeUse machine language

History of Computer DevelopmentApple Computer

Found by Steve Jobbs dan & Steve Wozniak in 1977First computer with easy to use screen and keyboard

History of Computer Development

Computer GenerationFirst Generation

1940s early 1950sVacuum tube as switchBulky, slow, easily heatedAlways fail ABC, MARK1, ENIAC, UNIVACStored program concept (Von Neumann)Assembly Language

Computer GenerationSecond Generation

1950s mid 1960transistor as switch Smaller and faster (x1000)Less heat, more reliable, cheapThe usage of high level language beginsDEC-PDP-1

Computer GenerationThird Generation

Late 1960sSilicon chip as switchSmaller and faster (x1000)More reliable

Computer GenerationFourth Generation

1970s currentSingle processor microchip as switch Very low cost and afforded by individual

HISTORY AND COMPUTER REVOLUTION

Programming Language

GenerationProgramming Language1Machine Language2Assembly Language3High Level Language4Very High Level Language5Natural Language

Programming LanguageAssembly language

Low level Use mnemonic code, abbreviation Program written in this language is translated by assembler into machine language program code before execution

Programming LanguageHigh Level Language

Exist 1960Similar to English Program written in this language is able to overcome more complex problem/taskTranslator is known as compiler which change program to machine language before executionCommercial application such as C/C++

Programming LanguageVery High Level Language

Known as 4GLProgram is written shorthand formAble to handle hundreds instruction lines (3rd generation language can handle few lines only)Example: Query Language

Programming LanguageNatural Language

Similar to spoken English LanguageNatural Language translate human instruction into codes that understandable by computer Also known as knowledge base languageInteract with knowledge base

UNIT OF MEMORY

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