computing informatics l 10 16[1]

8/12/2019 Computing Informatics L 10 16[1]

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Computing & Informatics L-10

Microprocessors

Memory

Semiconductor Memory

Memory Controller

Magnetic Memory

Optical Disks

PCMCIA cards and slots


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Microprocessors

Intel 80386 32 bit microprocessor. 386Sl version developed for laptop computers. Designed to consume low power. 32 bit data bus and 32 bit address bus.Intel 80486 32 bit microprocessor, implemented in CHMOS Technology. It contains 32 bit CPU, a floating point processor, 8 Kb or 16 KB

cache. 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.



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Microprocessors

Pentium 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.Pentium IV 32 bit microprocessor and 64 bit on Pentium 4 HT

microprocessor. Operating frequency up to2.8 GHz.



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Memory Essential component of computer, stores data, programs and

results. Three kinds of memory in modern computers:Semiconductor Magnetic Optical memories Types of memories

Main memory Secondary (Auxiliary) memory


ROM Memory

Static

Memory

Memory

RAM Memory

Primary (Main) Memory

Masked ROM

Auxiliary (Secondary) Memory

Dynamic

MemoryPROM EROM EEROM


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Memory

The semiconductor memory is employed as main memory or primary 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 important programs such as OS, compliers etc. floppy disk CDs and

magnetic disks are used as back up memory. The cache memory is placed in between CPU and the main

memory. It is semiconductor memory, and is faster than mainmemory. Write through and write back cache schemes are used in

computers.



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Memory

The diagrams shown below represents the memory hierarchies as per the speed of operation.


CPU

PrimaryMemory

SecondaryMemory

CacheMEM

PrimaryMemory

SecondaryMemory

CPU


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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 tillthe 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.



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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 of

information. SDRAM (Synchronous DRAM): these RAM chips uses the same

clock 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 small printed ckt cards on which several DRAM chips are placed.



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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 the

user. The user can store permanent programs using PROM programmer.

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 in

one chip to form non volatile RAM.



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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. Provides

multiplexed address, address strobes, refresh logic, and refresh /access arbitration.Intel 8207: is dual port DRAM controller. It interfaces 16K, 64K and

256K 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.



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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 oriented parallel to the disk surface along the track) and Vertical recording( 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 is

divided into sectors.



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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 + timerequired 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. Data

separation error detection also taken care by DC



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Magnetic Memory

Hard Disk: On line storage device connected permanently to computer. Made up of Aluminum. With thin coating of magnetic material over

it.

Read write head and disks are kept in sealed, air filtered enclosure To increase capacity several hard disks are mounted on common

drive 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.



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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. 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 has

more capacity to store data than a CD. It contains more layers.



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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 drive

mounting bays. These slots can be used for exchanging data using PCMCIA

cards. Type-I type has 34 pin connector 3.3 mm thick, whereas type-II

cards 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.



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Input Output Devices

Keyboard

Mouse

Monitor

Printer

Other I/O devices

Software


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Input 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 suitable

binary form which can be accepted by the computer. 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 and

provide 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 display

etc.



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Keyboard

Programs and data are entered into a computer through Keyboard. It is similar to a typewriter. It contains alphabets, digits, special

characters and some control Keys. When a key is pressed a signal is produced which is detected by

keyboard encoder and encoder sends a binary code to thecomputer.

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 layout

known as Dvorak layout. Construction of keys can be Mechanical Keyswitch, Capacitive

Keyswitch or Hall Effect Keyswitch.



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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 underside

of the mouse. The pulses transmitted by the mouse (generated by shaft encoder

for 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 optical

shaft angle encoders to convert motions to electrical signals.



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Monitor A CRT (Cathode Ray Tube ) display unit or monitor is a

commonly used out put device. It can display the data information received from computer in

alphanumeric character and graphs. Though CRT is basically O/p device but it can perform limited

input operations when used in conjunction with light pen. The CRT is similar to TV screen. It is vacuum tube . An electron

beam is produced and directed towards the front of the CRT. A coating of phosphor material is made up in the inner side of

screen. It emits light when struck by an electron beam. To produce colour display three phosphor red blue and green are

used. Three different beams for each colour is produced in such away that these beams struck the corresponding colour phosphor

dot arranged in a special manner.



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Monitor Raster Scan and Vector display methods are used in the CRT to

produce the out put. In raster scan method the electron beam is first directed at the top

left 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 thesecond line in same manner.

In the last line scan when beam reaches in the right hand side

bottom 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.



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Monitor A character is displayed on the screen by light dots. A matrix of

dots 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 each

character.

The ASCII or EBCDIC codes of the character to be displayed arestored in a display RAM or video RAM.

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.



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Printer s

Printers are commonly used out put device. These are classifiedas: Character Printer, Line Printer and Page Printer. The other classification based on the technology on

manufacturing are: Impact printer (uses electromechanical

mechanism that causes hammers or pins to strike against againsta ribbon to print) and Non-impact printer (uses thermal,chemical, 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 the

printer. In a dot matrix impact type character printers a character is

printed by printing selected number of dots from a matrix of dots. The line printer prints one line at time.



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Printer s

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 room

temperature. At the time of printing inks are melted and flow tothe reservoirs in the print head. Laser jet printers are page printers in which entire page is

processed 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 photoconductive

material.



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Other Input and Output Devices

Light pen A light pen is a pointing device, used to select a displayed menu

option on the CRT. It is photosensitive pen like device. It can also be used for graphics work

Joystick It is also a pointing device, used to move the curser position on a

CRT 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.



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Other Input and Output Devices

Scanners It is a kind of input device. These are capable of enetring

information directly into the computer.Optical scanners

The Optical scanners are capable of reading information recordedon paper employing light sources and light sensors.

Touch screen Some computers have touch screen which is sensitive to user s

touch. One can use finger to point the command displayed on thescreen. It is popular on laptops



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Software

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 user s program

is system S/W. It consist of operating system, assembler,complier, 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 certain

problem is known as Users program . The operating system is collection of programs that controls the

overall operation of a computer.



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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 and

program development. The firm ware is used for the S/W stored in read only storagedevice. These programs are never expected to change.

The way of writing the programs in a computer system depends

upon the programming language used. Programming language istool for writing the application program. Language are of two types: Low level Language and High Level

Language.



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Software

Each microprocessor has its own instruction set andcorresponding machine codes. To solve the difficulty in writing programs in machine language

assembly language have developed.

In assembly language the programs are written in alphanumericsymbol code known as mnemonics. The programming in assembly language is easier and fester as

compared to machine language programming.

Assembler : A program which translate an assembly language program into a machine language program is called assembler. An assembler which runs a computer for which it produces object

code (machine code) is called self assembler.



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Software A cross assembler is an assembler that run on a computer other

than for which it produces machine codes. One-Pass Assembler : an assembler which reads the assembly

language program only once. Two-Pass Assembler : an assembler which reads the assembly

language program twice. The computation time of assembly language program is les as

compared to High Level Language. Assembly language programs runs faster to produce the desired

result as compared to High Level Language. Assembly language programs can not used on any other computer

as compared to High Level Language. Assembly language program contains more instruction as

compared to High Level Language.



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Software A complier is a program which translate a high level language

into machine language. It is more intelligent than an assembler.it check for all kinds of

limits, ranges, errors etc. Its program execution time is more.it has low sped and low

efficiency of memory utilization. If a complier runs on computer for which it produces the object

code, then it is called self or resident complier. If a complier runs on computer other than that for which it

produces the object code, then it is called cross complier. An Interpreter is a program which translates statements of a high

level language into machine codes. It translate one statement at a time. A complier is faster than an interpreter.



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SoftwareProgramming language generations First Generation, 1GL : machine languages is known as first

generation Language. Second Generation, 2GL : an assembly language is second

generation Language. Assembly language is machine oriented. Itis very close to the hardware of the CPU.

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 oriented

languages are the fourth generation Language. In this language programmer has to tell only what to do.Java, C++, ORACLE and

SYBASE are example of these languages.


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Operating Systems

MS-DOS

UNIX

WINDOWS

Utility Programs

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Operating System It is an organized collection of software consisting of procedures

for 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 acomputer system.

OS directly controls computer computer system resources. Two ways to interact with OS:System Call: provides the interface between a running program and

the OSOperating system Commands: in this method user may interact with

OS directly by means of operating system commands.


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Operating System OS may process its tasks serially (sequentially) or concurrently

(several task simultaneously. The OS may employ serial processing, batch processing, multi

programming or multi tasking.Serial processing: In serial processing all the Datas or programs are processed

serially one by one. This result in low utilization of resources.Batch Processing: Jobs with similar requirements are batched together and run

through the computer as a group. Batching similar jobs improve utilization of system resources

quite a bit.


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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, during

execution the program may need some I/O operation to complete.In that time OS will simply switch to some other program insteadof sitting idle.

This offers a more efficient approach to increase system performance.

Multi Tasking: In multi tasking a program is divided onto different independent

tasks and this tasks runs on computer as independent programsrunning on the computer.

This improves the computation time as well as the resourceutilization.


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Operating System The operating system can be broadly classified as:

Batch Processing Operating systems: Batch operating system allow little or no interaction between

users and executing program. Process scheduling, memory management, file management and

I/O management are quite simple. Jobs are typically processed in first come first serve basis. The difficulties with this OS is non interacting environment and

of line debugging.

Multi Programming Operating systems MOS has a significant potential for improving system throughput

and resource utilization. Different forms of MOS are multitasking, multiprocess and multi-

user operating system.




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Operating SystemMulti Programming Operating systems A running state of program is called process or task. Multi programming supports multiple concurrent process to reside

in primary memory simultaneously. Multi tasking operating system allows two or more active process

simultaneously. Multi user operating system allows simultaneous access to acomputer system through two or more terminals.

Multiprogramming implies multiprocessing multi tasking but

multiprocess or multi tasking does not imply multiprogramming.Network Operating systems A NOS is a collection of S/w and associated protocols that allows

a set of autonomous computers which are interconnected by a

network to be used together in a convenient and cost effectivemanner.




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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 different

environment.

User are aware of where each of files are kept and must move filefrom one system to another with explicit transfer commands. NOS allows users to access the various resources of the network

host.

Controlling access so that users with proper authorization areallowed to access particular resources. Making the use of remote resource appear to be identical to the

use of local program.

Providing up-to-the minute N/w documentation on-line.



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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 in

debugging and verification of system easily. The layers are designed in a way that it uses operating and

services only if a layer below it. A higher layer

need not know how theseoperations are implemented.


Layer 5 User program

Layer 4 Buffering for I/O devices

Layer 3 Device driver

Layer 2 Memory manager

Layer 1 CPU scheduling

Layer 0 Hardware



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Operating 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.Virtual Machine It is a concept which creates an illusion of real machine. It is created by a virtual machine system that makes real machine

appear to be several real machine.Client Server Model In this model a user process (client process) sends an request to a

server process, which then does the work and send the answer.




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MS-DOS The operating system for PCs are designed as a single user single

task 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 Process When power is turned on BIOS takes control, it checks for

available 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.




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MS-DOS DOS provides many user services like: Directory management which allows user to create search and

deletion of directories. Memory and file management for allocation and de-allocation of

memory 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 execute

user 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.




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UNIX Unix is multi user OS which facilitates time sharing and was written

in C language in 1973. The interface provided to user is simple but yet powerful. The file system used by UNIX is hierarchical which allows efficient

implementation and easy use.

UNIX considers all files to be a continuous sequence of characters. UNIX treats peripherals devices as if they are files. UNIX supports a scripting language called shell which allows

complex 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 or

an interpreter provided it has an interface that maps user request forOS services to the standard set of requests used by UNIX.




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UNIXComputing & Informatics L-12

Hardware

TestProcessing

USER

Terminal

DriversForegroundBackground

Editors

Pipes

Shell

Utilities

Type

settling

Compiler

Unix to Unixcopy UCP

Device Driver

Memory manager

Kernel

USER



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WINDOWS It is designed for home use.

It is a graphical user interface of Microsoft Corporation. The GUI provides picture oriented interface.

Windows presents programs, procedure, files, commands etc. asgraphical symbols.

The different versions of Windows are Windows-3, Windows-3.1,Windows-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.




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WINDOWS Windows 98 provides plug and play facility. It is also a

multitasking operating system. Windows-NT is 32 bit multi user OS. It provides multitasking

features. It can run on microprocessors of other companies otherthan Intel s.

Windows supports TCP/IP/IPX/SPX data link control formainframes.

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.




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Utility Programs The utility programs are software tools to help programmers in

developing, writing, debugging and documenting programs. They cane either file management or program development

utilities. File management utilities are part of OS. The program

development utilities help user in writing and testing programs. Editor: a program which permits programmer to enter modify

and store source program or text. File manager a program which permits to create, copy, update or

delete files on the disks. Loader a program that loads machine codes of program into

system Memory. Linker a program that links smaller programs to form a single

program.




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Programming Languages

Types of languages

Components of programming languages

Input and output statement

Assignment statement and Print statement

Subroutine and functions

Algorithm and flow-chart



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Programming Languages A program is set of instruction that are arranged in a sequence that

guides the computer to solve a problem. The process of writing a program is called programming. Many programming languages are available for writing various types

of application, system software.

System programming are designed to make the computer easier touse. An example is operating system.

At present c C++ languages are widely used to develop system S/w. Application Programs are designed for specific computer

applications such as payroll processing, inventory control etc. For writing application programs, the programmer does not need to

control the basic circuitry of a computer system. One can chose any languages for writing a program according to

need.

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Types of Languages

Machine language: A first generation language written in binary form

consist of two parts operation code and second is operand. Assembly language: Second generation language written in

mnemonics form (symbol format), needs an assembler for translation

into machine code. High Level Language: Third generation language written in English

like language, easy to write programs needs compiler for translation

to machine code. Fourth generation Language: 4GL is a high level language that

requires significantly fewer instruction to accomplish a task uses the

object oriented approach.

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Components of programming Languageomput ng n ormat cs -


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Components of programming Language To write a program in programming language the various concept

such as representation of Datas, methods of expressing mathematical

and logical relationship among data elements differs language to

language but this are necessary parts of language.

Variables, Constants, Data type, and expressions are the smallest

components of a programming language. Variable: a character or group of characters assigned by the

programmer 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, numbers

character and a specific set of specific operation that can be

performed on those values.

Components of programming Languageomput ng n ormat cs -


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Co po e ts o p og a g a guage 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 or

numeric), 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 sametype referred to by the same variable name.

Two Dimensional Array A (X,Y): it is used to represent the Datas

which are determined by two factors. It is defined by the rows andcolumn value.

Expression: every computer language specify as in which various

arithmetic operators are used and evaluated in given expression.


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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 for

the response from the user.

Output statements are used for providing the output of result of

expressions or output of programs on monitor (normally) or in the

output devices.

Some times the output may given file or printed in a paper

through printers.




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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 on

display screen.

The syntax is printf( XXXXX);

Print statement is also an output statement.

computer languages normally provides very rich facilities for

making the display as attractive as possible.




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Conditional and looping statement

This is one of the most important program structure that enables a

modern programmer to develop well structured programs.

It accommodates statements corresponding to alternate tasks to be

performed depending upon truth value of the condition. It has three components a conditional expression the truth value of

which determines the action and an optional clause which

determines the other task to be performed if value is not truth.

It is used to provide loop structure in the program. The purpose of

a loop is to repeat certain task until no more repletion is

desired.the for , while are most used loop statement.




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Subroutine and functions

While writing a program sometimes it is needed to repeat a group

of statement at several points.

Subroutine is group of statement that can be referred to at

different points in a program. It is group of statement that can be

executed from different points in program.

Function is rule or set of rules that assign one and only one value

of 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. The

code for this functions does not appear in program. It is inserted

by the computer when program is translated into machine code.

Co put g & o at cs 3



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Algorithm and flow-chart A computer works under instruction from the user.

For solving any problem on a computer, the necessary instructions

describing a scheme of solution for the problem are to be arranged

and supplied by the user.

The steps of of basic operations by following which a solution to a problem can be obtained constitutes what is called an algorithm.

Once an algorithm for a problem is prepared, it can be used

repeatedly 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 of

different steps of operation used in algorithm.

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Algorithm and flow-chart The steps of operations used in an algorithm should be elementary

that they can easily be performed by a computer, capable ofexecuting previously mentioned instructions only or by a man who

may not even have knowledge of the problem but capable of

performing some operations only. Very precise description for operations used in the steps of an

algorithm are necessary to avoid any sort of confusion.

Algorithm must always halt after a finite time for the input values

supplied to it.

Algorithm must be very simple and descriptive in nature.

p g

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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.

Algorithm to swap the value of X and Y or interchange the values ofX and Y.

1. Let a variable T.

2. T = X

3. X = Y

4. Y=T



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Algorithm 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*C

3. M = SA.

4. If SB > M then M = SB.

5. If SC > M then M = SC.6. S = 0

7. 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 angled

12. Stop.



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Algorithm and flow chart In flow charts the operations to be followed is represented by using

nodes 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.

Get the valueof variable

I/P & O/P box

A = A+1

Process Box

Is A>BDecision Box

StopStart/ Stop

Box



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go t a d ow c a t Flow chart for average of three numbers.

Start

Get valuesof X,Y, Z

ComputeSUM = X+Y+Z

ComputeAVE = SUM/3

Stop



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p g

The C Languages

Data types

Input and output statement

Assignment statement

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The C Languages C is a middle level language as it can function like a low level

programming 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 programs begin with main function.

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 Section

4 Global declaration section 5 Main () 6 {

7 Declarative statement 8 executable statement 9 }

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The C Languages As example the first program in C is as.

/* This introductory program in C*/# include

Main ()

{

Printf ( Learn C Programming);

}

The second line # include is 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.

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yp 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 in program. 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 or

exponent or combination of both. Character constant is any symbol or value that is the part of valid

list. Strin is se uence of characters.



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yp Variables: A variable is the meaningful name assigned represent

a 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 special

symbol.

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 the program. Result of an computational statement may be assignedto a variable.



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yp Relational Operator: it is used to compare the value of two

variable 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.



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yp Library Functions: the library functions are the well defined

functions 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 headerfiles. 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 are

supplied with the compiler.

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p p Input instruction is provided for getting necessary input from the

user 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 the

variable in to which the value or data from the standard input will be 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 must

preceded by & sign.

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p p Output statement or instruction is provided for giving necessary

output 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 charactersfor 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=7

Where 3 is value of integer1,4 is value of integer2 and 7 is the valueof integer3.

Each format must start with % sign.

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Assignment statement Assignment operators are used to assign the result of

computational 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 value

will be assigned to variable X.Shorthand operator X+=3 is equal to X=X+3; X*=X is equal to

X=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 variable

A 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.



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Information system for decision making

Data management

Database management technology

Office automation system-LAN, WAN

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Information system for decision making A system is a group of interrelated component working together

towards 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.), the

given input is processed in processing element where the outputgenerated as per the requirement.

In the system feedback and control is used and such system iscalled 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.



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A computer based information system has five basic componentshardware software Data people and network.

Hardware is physical computer equipment used to input output and processing, software is a computer program that includes the processing 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. Network are used to connect the computers and equipment in a

building around a country or around the world. Decision making can be classified by organizational level

corresponding to the strategic, management, knowledge andoperational levels of the organization.

Unstructured decisions are those in which decision maker must provide judgment evaluation and insights into problem definitions.

Structured decisions are repetitive and routine and involve adefinite procedure.



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Information system for decision making Normally the decision making consist of four stages intelligence,

design choice and implementation.

Structured

Unstructured

Semi-structured

Operational Knowledge Management Strategic

TPS

Officesystem

KWS

MIS

DSS

ESS

TPS- Transaction processing system MIS- Management information system

KWS- Knowledge work station DSS- Decision support system

ESS- Executive support system



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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.

Decisionmaker

Managementwork station

Interactivedecisionsupport

Database

ManagementDialogue generationand management

DSS generatorModel Management

database

Model base

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g Data management is the most important aspect for an organization

since 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 with

smallest data used by computer (bit). Character data is basic building block of information.

Characters are put together to form a field. A collection of related

fields 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.



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g An entity is a generalized class of people, places or things for

which 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 is

a 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 and

stored for each application program. One of the flaws of traditional file oriented approach is data

duplication 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.



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g Database approach utilizes the Datas in a more efficient way. A

pool 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, better

protection, standardization of data access etc.

Database approach has some disadvantages like increased costand 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 logical

database models hierarchical, network and relational.



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g In a hierarchical database model, the data is organized in a top

down 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 twodimensional tables called relations that are logical equivalent tothe files.

The process of taking complex set of data and converting it into a

set of simple tables is called data normalization. Basic data manipulations include selecting, projecting and

joining. The data cleanup is used to develop the accuracy, flexibility,

relevancy, simplicity, verifiability in the data.

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A database management system (DBMS) is a group of programsused as an interface between a database and application programs

or a database and the user. A dataware house is multidimensional database and is capable of

storing very large amount of data generated from businessapplications.

To retrieve data from the dataware house data mining tools arerequired.

A DBMS also acts as a user interface by providing a view of thedatabase. A subschema is file that contains the description of

subset 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 and

commands used to define and describe data and data relationship

in a specific database.


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Office automation system-LAN, WANComputing & Informatics L-15


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y , Office automation system simply helps in making an automated

office 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 and

Extranet are classified. Internet: a world wide system of computer network which is helpful

to any office for providing connectivity with out side world. The internet provides a synthesis of computing and communication

capabilities that adds valued to every part of the business cycle. An Intranet is a network within the organization. It uses

information technology like web browser, and servers, TCP/IPclient server network, hypermedia management system, HTML,

network management and security technology etc.



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y , An extranet is a network that links selected resources of the intranet

of an organization with its regular customers.

Computer networks are required to facilitate Internet, Intranet orExtranet.

The computer networks are used to provide the file transfer between two systems, electronic mail (E-mail), execute a program

on another computer, remote login, to share peripherals devicessuch 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 are

important parameters to sorted out before a network is established.


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yTransmission 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.

Network topology Design: The topology means the form. Network may have any one of the

following forms. Star topology each device is connected to a central device called

hub the communication between to DTE is by using Hub only notdirectly.

In tree topology the equipment are connected in a hierarchicalmanner.



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Network topology Design: In Bus topology the equipment are connected with each other using

a common bus. Ring topology a ring of connected equipment is formed. In mesh topology the each equipment is connected to each

equipment using a dedicated link.Categories of network. Computer networks that are confined to a localized are I.e. an office

are 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 area

Network (WAN).



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C language

Control Structure

Array

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Decision making and looping is one of the basic construct of any programming 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 the

out come of expression in If is true then the group of statementmentioned in Then clause is executed otherwise Else is executed.

If (condition expression)

{ Statement set1; }Else

{ statement set2; }

Control Structurel f h b



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/* largest of three numbers */# include Main (){

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);

}else{ 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



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#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);

}else{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();

}



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While statement: is provided for repeated execution ofstatements. The statements are executed until the condition is

fulfilled. While (condition expression){Statement set;

}/* this is a program to calculate m to thepower n*/#include#includemain(){int m,n,count;Float pow;



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/*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(count


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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 = 32 On second run:This program gives the M to power NPlease give value of M and N

11 6

The 11 to the power 6 is=1771561.000000


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For statement: it is also provided for repeated execution ofstatements. The statements are executed until the condition isfulfilled.

for (expression1; expression2; expression3){Statement set;}

So in the program to calculate the m to the power n will be as :for (count=1;count


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switch statement: this statement in C provides the multiple branch selection. It checks for value of an expression against a listof integer or character. If the match is successful, the group ofstatement is executed

Switch (expression){

case constant 1:Statement set2;

break;case constant 2:Statement set2;

break;case constant 3:

Statement set3;

break;..Default:Statement set3;}

Control StructureB k d G h d i C



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Break 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


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All the arrays declaration define the maximum size of an arraythus they are called static array.

In C flexibility is provided for not defining the size of an array.

A programmer may leave the size of an array unspecified.the totalnumbers of entries specified in the list of values defines the

maximum size of array.Int student[ ] = {12,13 12, 14};

It is not possible to process an array in a single shot. If anoperation is to be done on array, it must be element basis. This isusually done using For loop, Do-while etc. on element basis.

In the next slides the multiplication of two matrix is explainedusing the arrays.

Arrays/* The program for the multiplication of two matrix */



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#include

#include

#define M 5

void main()

{

int i,j,r1,r2,c1,c2,x;

int a[M][M],b[M][M],c[M][M];

clrscr();

printf("program for multiplication of two matrix\n");printf("The column of FIRST Matrix should be equal to row of SECOND

Matrix\n");

printf("Give the no of rows in the First Matrix\n");

scanf("%d",&r1);

printf("Give the no of column in the First Matrix\n");

scanf("%d",&c1);

printf("Give the no of rows in the Second Matrix\n");

scanf("%d",&r2);

printf("Give the no of column in the Second Matrix\n");

scanf("%d",&c2);

Arrays/* To check the possibility of multiplication*/



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p y pif(c1!=r2){

printf("The Multiplication is not Possible sorry^^^\n");}else{

/* To read the first MATRIX*/printf("Give the give the elements of first Matrix\n");

for(i=0;i


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/ o S ow t e st /

printf("The First Matrix is \n");

for(i=0;i


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pfor(i=0;i


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The output of the program is as follows: program for multiplication of two matrixThe coloumn of FIRST Matrix should be equal to row of SECOND Matrix

Give the no of rows in the First Matrix2Give the no of coloumn in the First Matrix2Give the no of rows in the Second Matrix2

Give the no of coloumn in the Second Matrix3Give the give the elements of first MatrixGive the 1 row & 1 coloumn elementof first Matrix1Give the 1 row & 2 coloumn elementof first Matrix3Give the 2 row & 1 coloumn elementof first Matrix2Give the 2 row & 2 coloumn elementof first Matrix4

ArraysGive the give the elements of Second Matrix



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gGive the 1 row & 1 coloumn elementof Second Matrix1Give the 1 row & 2 coloumn elementof Second Matrix

3Give the 1 row & 3 coloumn elementof Second Matrix5Give the 2 row & 1 coloumn elementof Second Matrix2Give the 2 row & 2 coloumn elementof Second Matrix4

Give the 2 row & 3 coloumn elementof Second Matrix6The First Matrix is

1 32 4

The Second Matrix is

1 3 52 4 6

The Multiplied or Output Matrix is

computing informatics l 10 16[1]

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