Friday, March 27, 2009computing & informatics: short notesMicroprocessorsIntel 8085 8 bit microprocessor, implemented in NMOS Technology. 40 Pin LSI chip. 3, 5 and 6 MHZ are employed. 80 basic instructions and 246 opcode. 8 bit data bus and 16 bit address bus.Computing & Informatics L-102Intel 8086 16 bit microprocessor, implemented in HMOS Technology. 40 Pin LSI chip. 5, 8 and 10 MHZ are employed. 16 bit data bus and 20 bit address bus lines corresponds to 1MBmemory. 16 low order address lines are multiplexed with data line and 4high order address lines are multiplexed with status signal.MicroprocessorsIntel 80386 32 bit microprocessor. 386Sl version developed for laptop computers. Designed to consume low power. 32 bit data bus and 32 bit address bus.Computing & Informatics L-103Intel 80486 32 bit microprocessor, implemented in CHMOS Technology. It contains 32 bit CPU, a floating point processor, 8 Kb or 16 KBcache. 168 pin grade array or 196-lead plastic quad flat package. Different versions of 486 works between 25 100 MHz clock. Can directly address 4 GB memory.MicroprocessorsPentium with Multimedia extension (MMX) Operating frequency 200 MHz. Two cache 16 KB each. The MMX pipeline uses intensive parallel processing of data. The Celeron, Pentium II and Pentium III also uses MMX.Computing & Informatics L-104Pentium IV 32 bit microprocessor and 64 bit on Pentium 4 HTmicroprocessor. Operating frequency up to2.8 GHz.Memory Essential component of computer, stores data, programs andresults. Three kinds of memory in modern computers:Semiconductor Magnetic Optical memories Types of memoriesMain memory Secondary (Auxiliary) memory

ROM MemoryStaticMemoryMemoryRAM MemoryPrimary (Main) MemoryMasked ROMAuxiliary (Secondary) MemoryDynamicMemoryPROM EROM EEROMMemory The semiconductor memory is employed as main memory orprimary memory of the computer. RAM ROM IC are used as the main memory of computer. The magnetic and optical memory are used as secondary memory. Secondary memory is employed for bilk storage or mass storageof programs data and other information. Backup memory is used to store the copy of the importantprograms such as OS, compliers etc. floppy disk CDs andmagnetic disks are used as back up memory. The cache memory is placed in between CPU and the mainmemory. It is semiconductor memory, and is faster than mainmemory. Write through and write back cache schemes are used incomputers.

The diagrams shown below represents the memory hierarchies asper the speed of operation.Computing & Informatics L-10CPPrimaryMemorySecondaryMemory7UCacheMEMPrimaryMemorySecondaryMemoryCPUSemiconductor Memory Semiconductor are of two types: Random access Memory RAMand Read only memory ROM. The read write memory is commonly called RAM.RAMs RAM is volatile memory, the information exist in the memory tillComputing & Informatics L-108the power is on. Two types of RAM are: Static RAM and Dynamic RAM. Static RAM stores information as long as power is on. In case of Dynamic RAM the the information stored is lost invery short time (few milliseconds). Hence these are to berefreshed periodically. For this purpose RAM controller are used.Semiconductor Memory Static RAM uses Flip flops whereas Dynamic RAM uses gateswith capacitor so it requires less transistors per memory. Extended Data Output RAM (EDO-RAM): any memory accessstores bytes of data into latches. Latches holds next 256 bytes ofinformation. SDRAM (Synchronous DRAM): these RAM chips uses the sameComputing & Informatics L-109clock rate as the CPU, so it remains ready to transfer data whenneeded by the CPU. DRAM (Dual-Ported RAM: allows to access two memorylocations simultaneously, also called video RAM (VRAM orWRAM windows RAM) SIMM & DIMM: single inline & double inline modules are smallprinted ckt cards on which several DRAM chips are placed.Semiconductor MemoryROMs ROM is non-volatile memory, the information exist in thememory even if the the power goes off. Used fro permanentstorage of data. They are cheaper as compared to RAM. PROM: programmable ROM. Its content can be decided by theuser. The user can store permanent programs using PROMComputing & Informatics L-1010programmer. EPROM: in erasable PROM stored data can be erased byexposing it it to high intensive SW ultraviolet light. EEPROM: electrically erasable PROM can be erased andreprogrammed on board easily on a byte by byte basis. Flash memory: it is EEPROM but uses one transistor per cell. Nonvolatile RAM: high speed RAM & EEPROM are packed inone chip to form non volatile RAM.Memory Controller A dynamic RAM (DRAM) requires refreshing ckt to refresh thecontent, for this purpose DRAM controllers are evolved.Intel 8203: 64K DRAM controller capable of directly addressing anddriving up to 64 devices without external drivers. Providesmultiplexed address, address strobes, refresh logic, and refresh /access arbitration.Computing & Informatics L-1011Intel 8207: is dual port DRAM controller. It interfaces 16K, 64K and256K DRAMs. Can directly address 2 MB without any externaldrivers. A dual port interface permits two different busses toaccess memory independently.Intel 82C08: CHMOS DRAM controller. Can interface 64K and256K DRAMs. Can directly address 1MB. Capable of performingthe task of memory refreshing employing battery backup.Magnetic Memory It is permanent type memory. It is non-volatile. Used as secondaryand backup memory. Data is stored on the magnetic coating film by electrical pulses ofsuitable polarity to the magnetizing coil of a read /write head. Two techniques: longitude recording (magnetic region is orientedparallel to the disk surface along the track) and Vertical recordingComputing & Informatics L-1012( the magnetic regions are vertical to the disk surface). Types of Magnetic memory: Magnetic Disk (Hard Disks andFloppy Disk and Magnetic Tapes. Magnetic Disk is a surface device. Stores data on its surface. Surfaces is divided into concentric tracks and each track isdivided into sectors.Magnetic Memory The number of bytes stored in each sector is same. So all tracksstore same number of data. These disks are semi random devices. Track is selected in randomfashion but data is written or read in serial fashion. The time required to move the R/W head to the addressed sectoris access time (time to move head to the track is seek time + timeComputing & Informatics L-1013required to bring the starting position of the sector is latencytime). Disk Controller (DC) are required to convert instruction receivedfrom software to electrical pulses to operate disk. DC also issue commands to perform R/W operation. Dataseparation error detection also taken care by DCMagnetic MemoryHard Disk: On line storage device connected permanently to computer. Made up of Aluminum. With thin coating of magnetic material overit. Read write head and disks are kept in sealed, air filtered enclosureComputing & Informatics L-1014 To increase capacity several hard disks are mounted on commondrive to constitute disk pack.RAID Systems: Redundant Arrays of Inexpensive Disks (RAID) system disksoperate in parallel and stores the same information. Improves the storage reliability by eliminating the risk of data lost. Large files is stored in many disks by breaking the file into groups.Optical Memory Information is written in the disks using the laser beam. Provides the larger capacity. And has longer life. Slow access time of the drive. No chance of head crash, since head does not touch disk.Computing & Informatics L-1015 Three types CD ROM (prerecorded data can be read out)WROM ( write once and read many times)Erasable optical Disk (write many and read many times) Now DVD (Digital Versatile Disks) are also coming which hasmore capacity to store data than a CD. It contains more layers.PCMCIA Cards and Slots PCMIA stands for Personal Computer Memory Card InternationalAssociation. These are smart cards becoming standard feature fordesktop and portable machines. PCMCIA slots (socket) are designed to fit into floppy drivemounting bays. These slots can be used for exchanging data using PCMCIAComputing & Informatics L-1016cards. Type-I type has 34 pin connector 3.3 mm thick, whereas type-IIcards are 5 m thick and have 68 pins and type-III cards are 10.5mm thick and have 68 pin connector. Type-IV has 166mm thick. These cards and slots supports hot insertion.Computing & Informatics L-11 Input Output Devices Keyboard Mouse Monitor17 Printer Other I/O devices SoftwareInput and Output Devices The input/ output devices (I/O) and secondary storage units ofcomputer are called peripherals. Data and instruction are entered through input devices. An input device converts input data and instruction into suitablebinary form which can be accepted by the computer.Computing & Informatics L-1118 Some input devices are Keyboard, Mouse, light pen, joy stick,track ball, touch screen, graphic tablet etc. The out put devices receive information from the computer andprovide them to user. The computer sends information to O/p device in binary form.The O/p device converts into a form which is used by by user, Some O/p devices are Monitor, Printer, speakers, LCD displayetc.Keyboard Programs and data are entered into a computer through Keyboard. It is similar to a typewriter. It contains alphabets, digits, specialcharacters and some control Keys. When a key is pressed a signal is produced which is detected bykeyboard encoder and encoder sends a binary code to thecomputer.Computing & Informatics L-1119 The binary code may be an ASCII EBCDIC or Hex code. The binary code send by encoder is taken from a look up table. Computers use standard keyboards having Qwerty type layout. For faster typing keys are arranged to give a different layoutknown as Dvorak layout. Construction of keys can be Mechanical Keyswitch, CapacitiveKeyswitch or Hall Effect Keyswitch.Mouse A mouse is a pointing device. It is used to select a displayed menuon option on the CRT. It is held in on hand and moved across a flat surface. Movement is detected by the two rotating wheels on the undersideof the mouse.Computing & Informatics L-1120 The pulses transmitted by the mouse (generated by shaft encoderfor every incremental movement of the wheel) determine the thedistance moved. The mechanical mouse explained above picks up drift. An Opto-mechanical mouse has been developed. It contains a ball which rolls on two shafts. The shafts turn opticalshaft angle encoders to convert motions to electrical signals.Monitor A CRT (Cathode Ray Tube ) display unit or monitor is acommonly used out put device. It can display the data information received from computer inalphanumeric character and graphs. Though CRT is basically O/p device but it can perform limitedinput operations when used in conjunction with light pen. The CRT is similar to TV screen. It is vacuum tube . An electronComputing & Informatics L-1121beam is produced and directed towards the front of the CRT. A coating of phosphor material is made up in the inner side ofscreen. It emits light when struck by an electron beam. To produce colour display three phosphor red blue and green areused. Three different beams for each colour is produced in such away that these beams struck the corresponding colour phosphordot arranged in a special manner.Monitor Raster Scan and Vector display methods are used in the CRT toproduce the out put. In raster scan method the electron beam is first directed at the topleft hand corner and then it is moved along the first horizontalscan line. When it reaches right hand side the beam is turned of and retracerapidly left side to the starting point of second line and traces theComputing & Informatics L-1122second line in same manner. In the last line scan when beam reaches in the right hand sidebottom corner then it goes back to starting point (top left hand). In vector scan (random scan) method deflecting plates are used todeflect the beam left or right and up or down. The beam can be directed to any point on the screen.Monitor A character is displayed on the screen by light dots. A matrix ofdots is used for this purpose. The size of the dot-matrix may be 5x7, 7x9 or 7x12. Character generator ROM, stores the dot pattern for the eachcharacter. The ASCII or EBCDIC codes of the character to be displayed arestored in a display RAM or video RAM.Computing & Informatics L-1123 According to the character to be displayed the content of RAMchanges. A row counter and a character counter are employed to addressthe ASCII code of character in the display. A CRT controllers contains the necessary electronic CKT tocontrol CRT display. Several controller ICs like Intel 8275, 8276,822706 etc. are available.Printers Printers are commonly used out put device. These are classifiedas: Character Printer, Line Printer and Page Printer. The other classification based on the technology onmanufacturing are: Impact printer (uses electromechanicalmechanism that causes hammers or pins to strike against againsta ribbon to print) and Non-impact printer (uses thermal,Computing & Informatics L-1124chemical, electrostatic, laser beam, inkjet technology for printing) A character Printer prints one character of text at time. They arelow speed printers. Character to be printed are sent serially to theprinter. In a dot matrix impact type character printers a character isprinted by printing selected number of dots from a matrix of dots. The line printer prints one line at time.Printers An ink jet printers uses dot matrix approach to print text andgraphics. Most printers use multiple jets vertically aligned on acartridge. A solid colour printer use inks which are solid ar roomtemperature. At the time of printing inks are melted and flow tothe reservoirs in the print head.Computing & Informatics L-1125 Laser jet printers are page printers in which entire page isprocessed at a time. They use laser beam to produce an image of the page containingtext graphics on a photo sensitive drums. The drum is coated with negatively charged photoconductivematerial.Other Input and Output DevicesLight pen A light pen is a pointing device, used to select a displayed menuoption on the CRT. It is photosensitive pen like device. It can also be used for graphics workJoystick

It is also a pointing device, used to move the curser position on aCRT screen. Its function is similar to that of a mouse.Track pad It is one of the latest pointing device it looks like a small graywindow, about inches wide. One merely slides his fingers tipacross the window to move the curser.Other Input and Output DevicesScanners It is a kind of input device. These are capable of enetringinformation directly into the computer.Optical scanners The Optical scanners are capable of reading information recordedComputing & Informatics L-1127on paper employing light sources and light sensors.Touch screen Some computers have touch screen which is sensitive to userstouch. One can use finger to point the command displayed on thescreen. It is popular on laptopsSoftware A program is sequence of instruction. A set of programs written for a computer is called software. Software are of two typesSystem software: the software needed to execute the users programis system S/W. It consist of operating system, assembler,Computing & Informatics L-1128complier, interpreter, debugging programs text editors etc.Application software: the programs written for specific operationsmakes the application software. Programs like sales order,inventory, pay bills are examples of application S/W. A program which is prepared by programmer to solve certainproblem is known as Users program. The operating system is collection of programs that controls theoverall operation of a computer.Software The software which are helpful to users in developing, writing,debugging and documenting programs are referred as utilityprograms. There are two types of utility programs file management andprogram development. The firm ware is used for the S/W stored in read only storageComputing & Informatics L-1129device. These programs are never expected to change. The way of writing the programs in a computer system dependsupon the programming language used. Programming language istool for writing the application program. Language are of two types: Low level Language and High LevelLanguage.Software A language in which each statement is directly translated intosingle machine code is known as Low level language. Examples of low level language are machine level and theassembly languages of various processors. High level languages are written in form which is easy tounderstand and normally in the English like statement.Computing & Informatics L-1130 The instruction written in HL language are called statement. Thestatement more clearly resembles English and mathematics ascompared to mnemonics in assembly language. Machine language: programs written in the form of 0s and 1s iscalled machine language programs. There is a specific binary code for each instruction. These binarycode differs from computer to computer.Software Each microprocessor has its own instruction set andcorresponding machine codes. To solve the difficulty in writing programs in machine languageassembly language have developed. In assembly language the programs are written in alphanumericsymbol code known as mnemonics.Computing & Informatics L-1131 The programming in assembly language is easier and fester ascompared to machine language programming. Assembler: A program which translate an assembly languageprogram into a machine language program is called assembler. An assembler which runs a computer for which it produces objectcode (machine code) is called self assembler.Software A cross assembler is an assembler that run on a computer otherthan for which it produces machine codes. One-Pass Assembler: an assembler which reads the assemblylanguage program only once. Two-Pass Assembler: an assembler which reads the assemblylanguage program twice.Computing & Informatics L-1132 The computation time of assembly language program is les ascompared to High Level Language. Assembly language programs runs faster to produce the desiredresult as compared to High Level Language. Assembly language programs can not used on any other computeras compared to High Level Language. Assembly language program contains more instruction ascompared to High Level Language.Software A complier is a program which translate a high level languageinto machine language. It is more intelligent than an assembler.it check for all kinds oflimits, ranges, errors etc. Its program execution time is more.it has low sped and lowefficiency of memory utilization.Computing & Informatics L-1133 If a complier runs on computer for which it produces the objectcode, then it is called self or resident complier. If a complier runs on computer other than that for which itproduces the object code, then it is called cross complier. An Interpreter is a program which translates statements of a highlevel language into machine codes. It translate one statement at a time. A complier is faster than an interpreter.SoftwareProgramming language generations First Generation, 1GL: machine languages is known as firstgeneration Language. Second Generation, 2GL: an assembly language is secondgeneration Language. Assembly language is machine oriented. Itis very close to the hardware of the CPU.Computing & Informatics L-1134 Third Generation, 3GL: High Level Languages are the thirdgeneration Language. These are procedure-oriented languages.The programmer must tell what to do as well how to do.Fortran,Pascal, Cobol and C are examples of these languages. Fourth Generation, 4GL: Non-procedural or object orientedlanguages are the fourth generation Language. In this languageprogrammer has to tell only what to do.Java, C++, ORACLE andSYBASE are example of these languages.Computing & Informatics L-12 Operating Systems MS-DOS UNIX WINDOWS35 Utility ProgramsOperating System It is an organized collection of software consisting of proceduresfor operating a computer and providing an environment forexecution of programs. The objective of an OS is to make system convenient to use andutilize computer computer hardware in efficient manner. OS acts as an interface between users and the hardware of aComputing & Informatics L-1236computer system. OS directly controls computer computer system resources. Two ways to interact with OS:System Call: provides the interface between a running program andthe OSOperating system Commands: in this method user may interact withOS directly by means of operating system commands.Operating System OS may process its tasks serially (sequentially) or concurrently(several task simultaneously. The OS may employ serial processing, batch processing, multiprogramming or multi tasking.Serial processing: In serial processing all the Datas or programs are processedComputing & Informatics L-1237serially one by one. This result in low utilization of resources.Batch Processing: Jobs with similar requirements are batched together and runthrough the computer as a group. Batching similar jobs improve utilization of system resourcesquite a bit.Operating SystemMulti Programming: It allows more than one job (program) to utilize the CPU time atany moment. When OS picks one program and start executing, duringexecution the program may need some I/O operation to complete.In that time OS will simply switch to some other program insteadof sitting idle.Computing & Informatics L-1238 This offers a more efficient approach to increase systemperformance.Multi Tasking: In multi tasking a program is divided onto different independenttasks and this tasks runs on computer as independent programsrunning on the computer. This improves the computation time as well as the resourceutilization.Operating System The operating system can be broadly classified as:Batch Processing Operating systems: Batch operating system allow little or no interaction betweenusers and executing program. Process scheduling, memory management, file management andI/O management are quite simple.Computing & Informatics L-1239 Jobs are typically processed in first come first serve basis. The difficulties with this OS is non interacting environment andof line debugging.Multi Programming Operating systems MOS has a significant potential for improving system throughputand resource utilization. Different forms of MOS are multitasking, multiprocess and multiuseroperating system.Operating SystemMulti Programming Operating systems A running state of program is called process or task. Multi programming supports multiple concurrent process to residein primary memory simultaneously. Multi tasking operating system allows two or more active processsimultaneously. Multi user operating system allows simultaneous access to aComputing & Informatics L-1240computer system through two or more terminals. Multiprogramming implies multiprocessing multi tasking butmultiprocess or multi tasking does not imply multiprogramming.Network Operating systems A NOS is a collection of S/w and associated protocols that allowsa set of autonomous computers which are interconnected by anetwork to be used together in a convenient and cost effectivemanner.Operating SystemNetwork Operating systems Each computer has its own OS instead of running part of globalsystem wide operating system. Each user normally works on its own system on same or differentenvironment. User are aware of where each of files are kept and must move filefrom one system to another with explicit transfer commands.Computing & Informatics L-1241 NOS allows users to access the various resources of the networkhost. Controlling access so that users with proper authorization areallowed to access particular resources. Making the use of remote resource appear to be identical to theuse of local program. Providing up-to-the minute N/w documentation on-line.Distributed Operating systemsOperating SystemDistributed Operating systems A DOS operating system is one that looks to its users like anordinary centralized operating system but runs on the multipleidentical CPUs. The key is transparency. This allows programs to run on several processors at the sametime, thus requiring more complex processor schedulingComputing & Informatics L-1242algorithms in order to achieve maximum utilization of CPU time. DOS are considered to be more reliable than uniprocessor system. The OS performs even if certain parts of system (H/W) ismalfunctioning. Incremental growth is possible on this operating system. Large systems are made by using the small processor, henceprovides the price performance advantage over traditional system.Operating System StructureLayered structure approach In layered structure number of layers (levels), each built uponlower level, makes the operating system. The bottom layer is hardware and top layer is user interface. The main advantage of this is modularity which helps indebugging and verification of system easily.Computing & Informatics L-1243 The layers are designed in a way that it uses operating andservices only if a layerbelow it. A higher layerneed not know how theseoperations are implemented.Layer 5 User programLayer 4 Buffering for I/O devicesLayer 3 Device driverLayer 2 Memory managerLayer 1 CPU schedulingLayer 0 HardwareOperating System StructureKernel approach Kernel is part of OS which directly makes interface with hardware It provides mechanism for creation and deletion of processes. It provides processor scheduling It provides mechanism for synchronization of processes. It provides mechanism for interprocess communication.Computing & Informatics L-1244Virtual Machine It is a concept which creates an illusion of real machine. It is created by a virtual machine system that makes real machineappear to be several real machine.Client Server Model In this model a user process (client process) sends an request to aserver process, which then does the work and send the answer.MS-DOS The operating system for PCs are designed as a single user singletask operating system. This has two parts BIOS(Basic Input Output System) and DOS(Disk Operating System). The BIOS is stored in ROM and DOS in floppy disks.Booting ProcessComputing & Informatics L-1245 When power is turned on BIOS takes control, it checks foravailable H/w, then it reads from disk a small portion of OS andloads it into memory. This Boot program the pulls the rest of OS from the disk stored inmain memory and completes the booting process. BIOS is responsible for low level services.MS-DOS DOS provides many user services like: Directory management which allows user to create search anddeletion of directories. Memory and file management for allocation and de-allocation ofmemory and allow user to create edit write read the files. Command interpreter to interpret commands issued by the user. Executive functions which provides programs to load and executeComputing & Informatics L-1246user program retrieve error codes, correct and rerun the program. Some utility programs for house keeping cores.File management it is one of the most useful services of an OS. Filemanagement is supposed to hide all device specific aspects of filemanipulation from user and provide them with an adstract of asimple, uniform space of named files.File organization is a simple byte sequence. OS does not impose anystructure on file organization.UNIX Unix is multi user OS which facilitates time sharing and was writtenin C language in 1973. The interface provided to user is simple but yet powerful. The file system used by UNIX is hierarchical which allows efficientimplementation and easy use. UNIX considers all files to be a continuous sequence of characters.Computing & Informatics L-1247 UNIX treats peripherals devices as if they are files. UNIX supports a scripting language called shell which allowscomplex jobs to be performed using several built in programs. UNIX assumes on Knowledge of machine architecture from the user. UNIX can support any programming language that has a compiler oran interpreter provided it has an interface that maps user request forOS services to the standard set of requests used by UNIX.UNIXComputing & Informatics L-12TestProcessingPipesShellUtilitiesTypesettlingKernel48HardwareUSERTerminalDriversForegroundBackgroundEditorsCompilerUnix to Unixcopy UCPDevice DriverMemory managerUSERWINDOWS It is designed for home use. It is a graphical user interface of Microsoft Corporation. The GUIprovides picture oriented interface. Windows presents programs, procedure, files, commands etc. asgraphical symbols. The different versions of Windows are Windows-3, Windows-3.1,Computing & Informatics L-1249Windows-3.11, Windows-95, Windows-98, Windows-2000 orWindows-Millennium, Windows-NT and Windows-XP. Windows 95 is a mixed 16 bit and 32 bit multitasking OS. Windows 98 is a faster and easy to use OS.it si a 32 bit operatingsystem. The internet online environment is more closely associated withWindows 98 desktop computers.WINDOWS Windows 98 provides plug and play facility. It is also amultitasking operating system. Windows-NT is 32 bit multi user OS. It provides multitaskingfeatures. It can run on microprocessors of other companies otherthan Intels. Windows supports TCP/IP/IPX/SPX data link control forComputing & Informatics L-1250mainframes. Windows-NT provides Client server working mode, which is usedin networking of computing systems. The Windows XP embedded OS is used in devices such as handheld computers, TV set-top-boxes and automated industrialmachines.Utility Programs The utility programs are software tools to help programmers indeveloping, writing, debugging and documenting programs. They cane either file management or program developmentutilities. File management utilities are part of OS. The programdevelopment utilities help user in writing and testing programs.Computing & Informatics L-1251 Editor: a program which permits programmer to enter modifyand store source program or text. File manager a program which permits to create, copy, update ordelete files on the disks. Loader a program that loads machine codes of program intosystem Memory. Linker a program that links smaller programs to form a singleprogram.Computing & Informatics L-13 Programming Languages Types of languages Components of programming languages Input and output statement52 Assignment statement and Print statement Subroutine and functions Algorithm and flow-chartProgramming Languages A program is set of instruction that are arranged in a sequence thatguides the computer to solve a problem. The process of writing a program is called programming. Many programming languages are available for writing various typesof application, system software. System programming are designed to make the computer easier toComputing & Informatics L-1353use. An example is operating system. At present c C++ languages are widely used to develop system S/w. Application Programs are designed for specific computerapplications such as payroll processing, inventory control etc. For writing application programs, the programmer does not need tocontrol the basic circuitry of a computer system. One can chose any languages for writing a program according toneed.Types of Languages Machine language: A first generation language written in binary formconsist of two parts operation code and second is operand. Assembly language: Second generation language written inmnemonics form (symbol format), needs an assembler for translationinto machine code.Computing & Informatics L-1354 High Level Language: Third generation language written in Englishlike language, easy to write programs needs compiler for translationto machine code. Fourth generation Language: 4GL is a high level language thatrequires significantly fewer instruction to accomplish a task uses theobject oriented approach.Components of programming Language To write a program in programming language the various conceptsuch as representation of Datas, methods of expressing mathematicaland logical relationship among data elements differs language tolanguage but this are necessary parts of language. Variables, Constants, Data type, and expressions are the smallestcomponents of a programming language.Computing & Informatics L-1355 Variable: a character or group of characters assigned by theprogrammer to a single memory location and used in the program. Constant: it has fixed value in the sense that its value cannot beequal to any other value other than already assigned in the program. Data Type: defines a set of related values/ integers, numberscharacter and a specific set of specific operation that can beperformed on those values.Components of programming Language Data Type: different type of data types are integers, character,strings etc. Array: an array is a collection of same type of data (either string ornumeric), all of which are referenced by the same name. Array: Normally two types of array are used. One dimensional Array A(X): it is a list of related data of sameComputing & Informatics L-1356type referred to by the same variable name. Two Dimensional Array A (X,Y): it is used to represent the Dataswhich are determined by two factors. It is defined by the rows andcolumn value. Expression: every computer language specify as in which variousarithmetic operators are used and evaluated in given expression.Components of programming Language An expression may contain operators such as (), ^, -, *, /, +,. The operators mentioned above are called mathematical operators. In a programming languages the logical operators are also used toperform the logical operations. Some of relational operators are = equal to, not equal to, < lesComputing & Informatics L-1357than, > greater than, = greater than equal to. Every operators used in programming language has order of priorityfor solving the expression among themselves. The logical operators are NOT, AND, OR, XOR, these four logicaloperators are sufficient to express any logical condition.Input and Output statement Input statements are normally used for supplying values to a listof variables through an input device such as key board. During execution of input statement the program halt or waits forthe response from the user.Computing & Informatics L-1358 Output statements are used for providing the output of result ofexpressions or output of programs on monitor (normally) or in theoutput devices. Some times the output may given file or printed in a paperthrough printers.Assignment statement and print statement This is the most used statement for assigning value to an identifier(i.e. variables). The syntax is : variable = expression (like X = A+B) This is a way to display values of specified list of variables onComputing & Informatics L-1359display screen. The syntax is printf( XXXXX); Print statement is also an output statement. computer languages normally provides very rich facilities formaking the display as attractive as possible.Conditional and looping statement This is one of the most important program structure that enables amodern programmer to develop well structured programs. It accommodates statements corresponding to alternate tasks to beperformed depending upon truth value of the condition.Computing & Informatics L-1360 It has three components a conditional expression the truth value ofwhich determines the action and an optional clause whichdetermines the other task to be performed if value is not truth. It is used to provide loop structure in the program. The purpose ofa loop is to repeat certain task until no more repletion isdesired.the for , while are most used loop statement.Subroutine and functions While writing a program sometimes it is needed to repeat a groupof statement at several points. Subroutine is group of statement that can be referred to atdifferent points in a program. It is group of statement that can beexecuted from different points in program.Computing & Informatics L-1361 Function is rule or set of rules that assign one and only one valueof X to give value Y. For Y = f(X) here Y is a function of X. Library functions are supplied by the language by default. Thecode for this functions does not appear in program. It is insertedby the computer when program is translated into machine code.Algorithm and flow-chart A computer works under instruction from the user. For solving any problem on a computer, the necessary instructionsdescribing a scheme of solution for the problem are to be arrangedand supplied by the user. The steps of of basic operations by following which a solution to aComputing & Informatics L-1362problem can be obtained constitutes what is called an algorithm. Once an algorithm for a problem is prepared, it can be usedrepeatedly for solving as many as instances of problem. A pictorial description of algorithm is used and is called Flow-chart. It also represent a clear graphical description of interdependence ofdifferent steps of operation used in algorithm.Algorithm and flow-chart The steps of operations used in an algorithm should be elementarythat they can easily be performed by a computer, capable ofexecuting previously mentioned instructions only or by a man whomay not even have knowledge of the problem but capable ofperforming some operations only.Computing & Informatics L-1363 Very precise description for operations used in the steps of analgorithm are necessary to avoid any sort of confusion. Algorithm must always halt after a finite time for the input valuessupplied to it. Algorithm must be very simple and descriptive in nature.Algorithm and flow-chart Examples: find the Average of any three numbers.1. Get the values of three numbers.2. Compute the sum of the numbers.3. Divide the sum by 3 to obtain the average.4. Print the average value.5. Stop.Computing & Informatics L-1364 Algorithm to swap the value of X and Y or interchange the values ofX and Y.1. Let a variable T.2. T = X3. X = Y4. Y=TAlgorithm and flow-chart Algorithm to find the whether the given triangle is right angled.1. Get the values of A, B, C.2. SA = A*A, SB = B*B, SC = C*C3. M = SA.4. If SB > M then M = SB.5. If SC > M then M = SC.Computing & Informatics L-13656. S = 07. If SA M then S = S + SA.8. If SB M then S = S + SB.9. If SC M then S = S + SC.10. If S = M then print the triangle is right angled.11. If S M then print triangle is not right angled12. Stop.Algorithm and flow-chart In flow charts the operations to be followed is represented by usingnodes labeled with the symbols of operation and directed arcs. All nodes in a flow chart are not identical in shape. The shape of anode is determined by the type of operation it represent. Usually nodes are four types Input/Output boxes, Process boxes,Decision boxes and Start /Stop boxes.Computing & Informatics L-1366Get the valueof variableI/P & O/P boxA = A+1Process BoxIs A>BDecision BoxStopStart/ StopBoxAlgorithm and flow-chart Flow chart for average of three numbers.Computing & Informatics L-13StartGet valuesof X,Y, Z67ComputeSUM = X+Y+ZComputeAVE = SUM/3StopComputing & Informatics L-14 The C Languages Data types Input and output statement Assignment statement68The C Languages C is a middle level language as it can function like a low levelprogramming language to speed up processing as well as it canalso work like high level language. Program written in C contains one or more function. A C program must contain a function called main and programsbegin with main function.Computing & Informatics L-1469 The comments may also be incorporated for description purpose.The comment must be bounded by /* comments*/ The comment are omitted during compilation by compiler. Basic block structure in C is1 comment line 2 link Section 3 Definition Section4 Global declaration section 5 Main () 6 {7 Declarative statement 8 executable statement 9 }The C Languages As example the first program in C is as./* This introductory program in C*/# includeMain (){Computing & Informatics L-1470Printf ( Learn C Programming);} The second line # includeis preprocessor directivewhich ensures reading an header file stdio.h. it is a command tothe processor pass of compilation to perform a specific task. The third line is beginning of C program main function.Data Types Character Set: four group namely letters a to z A to Z,digits,special character, white space are allowed in C. Identifiers: the word or names used to refer the variable,constant, function names are called as identifiers. A Key worddefined in the C should not be used for any identifiers. Constant: it is an identifier whose value does not change inComputing & Informatics L-1471program. The four categories are Integers, Real,Character andString. Integer constant refers to sequence of digits. Real constant is numeric constant with sign of decimal point orexponent or combination of both. Character constant is any symbol or value that is the part of validlist. String is sequence of characters.Data Types Variables: A variable is the meaningful name assigned representa data object. Variable name must start with a letter. Variable name can not begin with digit. It can not contain punctuation mark math symbol or other specialsymbol.Computing & Informatics L-1472 Reserved words name can not be used for variable name. ANSI restrict variable to be of 32 character. Variables are created to store the value of data object in theprogram. Result of an computational statement may be assignedto a variable.Data Types Relational Operator: it is used to compare the value of twovariable for various such as greater than, les than etc.> is greater than, >= is greater than equal to, < is less than, k) ? L : k here if L>k then Val will be = to l else Val = K.Data Types Library Functions: the library functions are the well definedfunctions for performing the specific task in a program. The compiler evaluates these functions. In C some mathematical functions are also allowed, thesefunctions are called mathematical functions. In order to use these library functions it is necessary to use headerComputing & Informatics L-1474files. The header files are logical collection of various functions. If the header files are not included the functions can not be used. Some of the common header files are stdio.h, math.h, conio.h etc. The library functions are not the part of the language but these aresupplied with the compiler.Input and Output statement Input instruction is provided for getting necessary input from theuser of the program. Scanf: this function is used to input a set of values.scanf(FS, list of arguments)Here FS is known as format string and list of argument contains thevariable in to which the value or data from the standard input willComputing & Informatics L-1475be stored.Example: scanf(%d %s %f, &integer1, string1,&integer2);This statement will store a decimal type integer data to integer1 (avariable defined in the program), string to variable String1 andfloating point value to integer2 variable from the standard input.Each format must start with % sign & each numeric variable mustpreceded by & sign.Input and Output statement Output statement or instruction is provided for giving necessaryoutput to the user of the program. printf: this function is used to print any combination of string,number or character to the standard output of computer (monitor).printf(FS, list of arguments)Here FS is known as format string and contains the format charactersComputing & Informatics L-1476for the corresponding variables.Example: printf(sum of %d and %d is = %d \n, integer1, integer2,integer3);This statement will give the output as sum of 3 and 4 is=7Where 3 is value of integer1,4 is value of integer2 and 7 is the valueof integer3.Each format must start with % sign.Assignment statement Assignment operators are used to assign the result ofcomputational statements. The assignment statement A O E; where a is variable and O isoperator and E is expression.Example: X = P+Q*R+Z-T;Here after evaluation of P+Q*R+Z-T expression the resultant valuewill be assigned to variable X.Computing & Informatics L-1477Shorthand operator X+=3 is equal to X=X+3; X*=X is equal toX=X*X, X/=B+C is equal to X=X?(B+C)and X-=2 is X=X-2. Increment operator A++ or ++A increments the value of variableA by one. The difference is that a prefix operator first operatesonce to the operand and then result is assigned to variable to theleft. Like A=1 B++A now A=2 and B=2 but B=A++ will be B=1and A+2. Similarly the decrement operator is A or A.Computing & Informatics L-15 Information system for decision making Data management78 Database management technology Office automation system-LAN, WANInformation system for decision making A system is a group of interrelated component working togethertowards a common goal in an organized manner. A system has three parts input, output and process. Input is given to the system (like raw material, Datas etc.), thegiven input is processed in processing element where the outputgenerated as per the requirement. In the system feedback and control is used and such system isComputing & Informatics L-1579called cybernetic system. Feed back is a part of output used for modifying the input toimprove the output. An information is a processed data or abstracted data from theavailable raw data. Information system is set of interrelated components that collectthe input and process it to provide the desired information(output) with the help of feedback and control system.Information system for decision making A computer based information system has five basic componentshardware software Data people and network. Hardware is physical computer equipment used to input output andprocessing, software is a computer program that includes theprocessing instructions to govern the operation of computer. People are the most important element in the most of systems asthey are required to operate the system. Data is basically raw facts and observations. It is a valuableorganized resource.Computing & Informatics L-1580 Network are used to connect the computers and equipment in abuilding around a country or around the world. Decision making can be classified by organizational levelcorresponding to the strategic, management, knowledge andoperational levels of the organization. Unstructured decisions are those in which decision maker mustprovide judgment evaluation and insights into problem definitions. Structured decisions are repetitive and routine and involve adefinite procedure.Information system for decision making Normally the decision making consist of four stages intelligence,design choice and implementation.Computing & Informatics L-15StructuredSemi-Operational Knowledge Management StrategicTPSOfficeMIS81UnstructuredSemistructuredsystemKWSDSSESSTPS- Transaction processing system MIS- Management information systemKWS- Knowledge work station DSS- Decision support systemESS- Executive support systemInformation system for decision making A decision support system is system that provides tools to mangersto assist them in solving semi structured and unstructured problems. A DSS is not intended to make decision but rather than to assist fordecision making. Characteristics of DDS are they support semi structured orunstructured decision making. They are flexible enough to respondto the changing needs of decision maker and they are easy to use. The component of a DSS are hardware, software and data isnecessary to provide interactive decision support.Computing & Informatics L-1582DecisionmakerManagementwork stationInteractivedecisionsupportDatabaseManagementDialogue generationand managementDSS generatorModel ManagementdatabaseModelbaseData management Data management is the most important aspect for an organizationsince it provides the ability to complete most business activities. Data management is a way of keeping the raw facts in specialmanner suitable to use it in efficient manner. Data is generally organized in a hierarchy that begins withsmallest data used by computer (bit).Computing & Informatics L-1583 Character data is basic building block of information. Characters are put together to form a field. A collection of relatedfields is record. A collection of related records is a file. At the highest level of this data hierarchy is data base, a collectionof integrated and related files.Data management An entity is a generalized class of people, places or things forwhich data is collected stored and maintained. An attribute is a characteristics of of an entity. A collection of fields about a specific object is a record. A Key isa field or set of records that is used to identify the records. Normally there are two ways to mange the data. In Traditional approach separate data files are created andComputing & Informatics L-1684stored for each application program. One of the flaws of traditional file oriented approach is dataduplication i.e. Data redundancy. When a change is made in onerecord it is not necessary that same will be done in other record. Data redundancy therefore conflicts with data integrity. In traditional approach another flaws is program-data dependence.Data management Database approach utilizes the Datas in a more efficient way. Apool of related data is shared by multiple application programs. Some of the advantages of Database approach are: Improvedstrategic use of corporate data, reduced data redundancy, easiermodification and updating data and program independence, betterprotection, standardization of data access etc. Database approach has some disadvantages like increased costComputing & Informatics L-1585and specialized staff and increased vulnerability etc. Data modeling and database models are key considerations forany organization to choose the right approach. A data model is a diagram of entities and their relationship.Entity-relationship (ER) diagrams use basic graphical symbols toshow the organization of and relationship between data. The structure in most database follows one of the three logicaldatabase models hierarchical, network and relational.Data management In a hierarchical database model, the data is organized in a topdown or inverted tree structure. In network model an owner-member relationship instead of one tomany relationship like in hierarchical model. The both models suffer from the deficiency that once therelationship is established the modification is difficult. In relational model all data elements are placed in twoComputing & Informatics L-1586dimensional tables called relations that are logical equivalent tothe files. The process of taking complex set of data and converting it into aset of simple tables is called data normalization. Basic data manipulations include selecting, projecting andjoining. The data cleanup is used to develop the accuracy, flexibility,relevancy, simplicity, verifiability in the data.Database management technology A database management system (DBMS) is a group of programsused as an interface between a database and application programsor a database and the user. A dataware house is multidimensional database and is capable ofstoring very large amount of data generated from businessapplications. To retrieve data from the dataware house data mining tools areComputing & Informatics L-1587required. A DBMS also acts as a user interface by providing a view of thedatabase. A subschema is file that contains the description ofsubset of the database and identifies which user can view andmodify the data items in that subject. A data definition language (DDL) is collection of instruction andcommands used to define and describe data and data relationshipin a specific database.Database management technology The important aspect of DBMS is storing and retrieving the datafrom database.when database stores a data it utilizes the logicalaccess path (LAP). Data manipulation language (DML) is collection of commandsthat are used to manipulate the database. Structured query language (SQL) lets programmers learn onepowerful query language and use it on systems from PCs to thelargest mainframe computers.Computing & Informatics L-1588 SQL uses standardized and simplified procedures for retrievingstoring and manipulating data in a database system. Database administration DBA is very important face of DBMSsince the key issues like security, authorization, networking orcommunication data from one user to other user is controlled byDBA. Some popular DBMS are coral's Paradox, FoxPro, Microsoftaccess, ORACLE etc.Office automation system-LAN, WAN Office automation system simply helps in making an automatedoffice having multiple functions to be performed. Presently business organizations are in the need of fast and accuratecommunication within the office as well as with their client so thata fully automated system can be developed. Basically three kinds of computer networks Internet, Intranet andExtranet are classified.Computing & Informatics L-1589 Internet: a world wide system of computer network which is helpfulto any office for providing connectivity with out side world. The internet provides a synthesis of computing and communicationcapabilities that adds valued to every part of the business cycle. An Intranet is a network within the organization. It usesinformation technology like web browser, and servers, TCP/IPclient server network, hypermedia management system, HTML,network management and security technology etc.Office automation system-LAN, WAN An extranet is a network that links selected resources of the intranetof an organization with its regular customers. Computer networks are required to facilitate Internet, Intranet orExtranet. The computer networks are used to provide the file transferbetween two systems, electronic mail (E-mail), execute a programon another computer, remote login, to share peripherals devicesComputing & Informatics L-1590such as printers and to provide teleconferencing etc. The computer networks must have security measures againstviruses and unauthorized access. The computer network must have reliability, less failure, lessaverage down time, protection from catastrophe, suitable hardwaresoftware & transmission media. The network cost and traffic load and fixed cost & runtime cost areimportant parameters to sorted out before a network is established.Office automation system-LAN, WAN The function of a communication network is to interconnect DTE(data terminal Equipment). DTE is a general term to identify the end user machine which isusually a terminal or computer. Some example of DTEs are ATM, mobile phone a workstation forair traffic control, a personal computer at home or office. The communication between DTEs depends or based upon theComputing & Informatics L-1591Channel configuration, Transmission mode, Network topologydesign, Categories of networks.Channel configuration: Point to point channel configuration provides a dedicated linkbetween two communication devices. Point to multi point channel provides a communication betweensingle transmitter to may receivers.Office automation system-LAN, WANTransmission mode: Simplex is way of communication in which direction of data flow isin one way only in a single channel. Duplex is way of communication in which direction of data flow isin both direction in a single channel. Half Duplex permits transmission in both direction but in a onedirection at time.Computing & Informatics L-1592Network topology Design: The topology means the form. Network may have any one of thefollowing forms. Star topology each device is connected to a central device calledhub the communication between to DTE is by using Hub only notdirectly. In tree topology the equipment are connected in a hierarchicalmanner.Office automation system-LAN, WANNetwork topology Design: In Bus topology the equipment are connected with each other usinga common bus. Ring topology a ring of connected equipment is formed. In mesh topology the each equipment is connected to eachequipment using a dedicated link.Categories of network.Computing & Informatics L-1593 Computer networks that are confined to a localized are I.e. an officeare known as local area network LAN. Computer network based on DQDB (distributed queue dual bus)mechanism designed to extend over an entire city is MetropolitanArea Network (MAN). Computer networks that covers large geographical areas that maycomprise a country a continent or even whole world is wide areaNetwork (WAN).Computing & Informatics L-16C language Control Structure94 ArrayControl Structure Decision making and looping is one of the basic construct of anyprogramming language. In C language the IFTHEN..ELSE, WHILE, DO..WHILE,FOR, BREAK and SWITCH are control structures statements. If Then Else statement: is provided for decision making. If theout come of expression in If is true then the group of statementComputing & Informatics L-1695mentioned in Then clause is executed otherwise Else is executed.If (condition expression){ Statement set1; }Else{ statement set2; }Control Structure/* largest of three numbers */# includeMain (){int a,b,c;printf (Please enter all the three A, B and C number\n);scanf (%d %d %d,&a, &b, &c);if (a>b){if(a>c){ printf(Largest number is %d\n, a);}Computing & Informatics L-1696else{ printf(Largest number is %d\n, c);}}else{if (c>b){ printf(Largest number is %d\n, c);}else{ printf(Largest number is %d\n, b);}}}Control Structure#include#includevoid main(){int a,b,c;char X;clrscr();printf (" please enter all the three numbers A B and C\n");scanf("%d %d %d",&a,&b,&c);if(a>b){if(a>c){printf("largest number is %d\n",a);}Computing & Informatics L-1697else{printf("largest number is %d\n",c);}}else{if (c>b){printf("largest number is %d\n",c);}else{printf("largest number is %d\n",b);}}getch();}Control StructureWhile statement: is provided for repeated execution ofstatements. The statements are executed until the condition isfulfilled.While (condition expression){Statement set;}Computing & Informatics L-1698/* this is a program to calculate m to thepower n*/#include#includemain(){int m,n,count;Float pow;clrscr();Control Structure/*body of program*/printf("This program gives the M to powerN\n");printf("Please give value of M and N\n");scanf("%d %d",&m,&n);count=1;pow = m;while(countComputing & Informatics L-1699{pow=pow*m;count++;}printf("\n The %3d to the power%3dis=%4d\n",m,n,pow);getch();return 0;}Control Structure The out put of the program will be as follows:This program gives the M to power NPlease give value of M and N2 5 *(press enter here)*The 2 to the power 5 is = 32Computing & Informatics L-16100 On second run:This program gives the M to power NPlease give value of M and N11 6The 11 to the power 6 is=1771561.000000Control StructureDo-while statement: is also provided for repeated execution ofstatements. The statements are executed until the condition isfulfilled.The difference with while statement is that condition isevaluated after execution of statements.Do{Statement set;Computing & Informatics L-16101} While (condition expression)So in the last program the condition with do-while will be as:do{pow=pow*m;count++;}while(countControl StructureFor statement: it is also provided for repeated execution ofstatements. The statements are executed until the condition isfulfilled.for (expression1; expression2; expression3){Statement set;Computing & Informatics L-16102}So in the program to calculate the m to the power n will be as :for (count=1;count{pow=pow*m;}Control Structureswitch statement: this statement in C provides the multiplebranch selection. It checks for value of an expression against a listof integer or character. If the match is successful, the group ofstatement is executedSwitch (expression){caseconstant 1:Statement set2;break;Computing & Informatics L-16103caseconstant 2:Statement set2;break;case constant 3:Statement set3;break;..Default:Statement set3;}Control StructureBreak and Goto statement: these statements are used in C tochange the flow of execution. The break is used in conjunctionwith switch case however this statement can be used todiscontinue the loop.Main(){int I=1;While (I