HARDWARE All the elements that go together to make up a PC fall into one of two categories, hardware or software.

Everything you can see and touch in your PC is hardware. Examples:

PC Case, Motherboard, Power Supply, Hard Disk Drive (HDD), Floppy Disk Drive (FDD), Compact Disk Drive (CDD), Digital Video Disk drive (DVD), Monitors (CRT and LCD), Keyboard, Mouse, Audio, Cables

6 MAJOR COMPONENTS OF COMPUTER

SOFTWAREThe Software in a computer system consists of programs-coded instructions created by programmers or users to tell the computer system what to do.

APPLICATION SOFTWARE Written for or by End Users to perform specific task to get desired output. Examples:

Software suites, Web browsers, Electronic mail, Word Processing, Spread sheets, Database managers, Presentation graphics, Personal Information managers and Groupware. Business Accounting Transaction processing, CRM, ERP, E-Commerce etc. Science and Engineering, Education, Entertainment etc.

SYSTEM SOFTWARE Performs the background work that makes it possible for application software to run

on computer hardware. Controls the internal operations and serves as an intermediate. Examples: OS, Network Management Programs, Database management Programs.

Program Language Translators, editors and tools.

PRODUCTIVITY TOOLS

MAJOR TYPES OF SOFTWARE

OPERATING SYSTEM Most Important type of System software. Software that manages and controls the activities of the Computer.

BASIC TASKS OF OS

Recognizing input from the Keyboard and Mouse. Processing the input. Sending output to the computer display. Keeping track of files and directories on disks. Sending documents to the printer.

OS FUNCTIONS Manages the operations of CPU. Controls the input/output and storage resources. Controls the activities of the computer system. Provides various support services as the computer executes the applications program

users.

MULTI-PROGRAMMING ENVIRONMENT Can computers execute only one instruction from one program at a time. Is it true..??? No is the answer.

Based on specialized OS(Classification): Multi-Programming, Multi-Tasking, Multi-Threading, Multi-processing. Time

Sharing, Virtual Storage.

MULTI-PROGRAMMING More efficient.(Executed Concurrently) Better memory management. Less time consumption.

MULTI-THREADING Ability of an OS to execute different parts of the same programs at the same time. Different processing parts of the same program are called Threads.

MULTI-SWITCHING: Switching between tasks.

MULTI-PROCESSING Capability of OS to make some CPUs to work in parallel.

TIME SHARING

OTHER ACTIVITIES OF OS Accounting and Statistical jobs. Recording logon logoff times. Number of seconds the operator used the CPU in every session. Number of pages a user printed. Hardware diagnostic. Disk check. File comparison, file sorting.

Note: OS will not provide all the utilities necessary; specially utility programs needed to carryout all.

THE OPERATING SYSTEM MEDIATION

GENERATION OF LANGUAGESTHE EVOLUTION OF PROGRAMMING LANGUAGES To build programs, people use languages that are similar to human language. The results are translated into machine code, which computers can understand to carry out instructions. Programming languages fall into three broad categories: Machine languages Assembly languages Higher-level languages

MACHINE LANGUAGE Machine languages (first-generation languages) are the most basic type of computer

languages, consisting of strings of numbers the computer's hardware can use. Different types of hardware use different machine code. For example, IBM

computers use different machine language than Apple computers.

ASSEMBLY LANGUAGE Assembly languages (second-generation languages) are only somewhat easier to work

with than machine languages. To create programs in assembly language, developers use cryptic English-like phrases

to represent strings of numbers. The code is then translated into object code, using a translator called an assembler.

HIGHER LEVEL LANGUAGE Third-generation languages (3GLs) are the first to use true English-like phrasing, use than previous languages.

making them easier to

3GLs are portable, meaning the object code created for one type of system can be

translated for use on a different type of system.

The following languages are 3GLs:

FORTAN, C, COBOL, C++, BASIC, JAVA, PASCAL, ACTIVEX.

FOURTH-GENERATION LANGUAGEFourth-generation languages (4GLs) are even easier to use than 3GLs. 4GLs may use a text-based environment (like a 3GL) or may allow the programmer to work in a visual environment, using graphical tools. The following languages are 4GLs: Visual Basic (VB), Visual Age, Authoring environments.

FIFTH-GENERATION LANGUAGE Fifth-generation languages (5GLs) are an issue of debate in the programming community some programmers cannot agree that they even exist.

These high-level languages would use artificial intelligence to create software, making 5GLs extremely difficult to develop.

Solve problems using constraints rather than algorithms, used in Artificial Intelligence. Eg:Prolog.

FOUR-LEVELS OF PROGRAMMING LANGUAGESGenera tion1 Ma chine L ng g a ua es Use Binary coded instructions 101011001 101111010 110011011 Genera tion2 Assem bler L ng g a ua es Use Symbol coded instructions LODY ADDZ STR X Genera tion3 H hL el L ng g ig ev a ua es Use brief statements of aruthmetic notations BASIC : X= Z Y+ COBOL : Compute X= Z Y+ Genera tion4 F ourthGenera tionL ng g a ua es Use natural and non-procedural statements. SUM THEFOLLOWINGNUMBERS

PROCEDURAL LANGUAGEProcedural languages were the first programming languages that were independent of hardware on which their programs run. Since typical procedural language has a richer vocabulary and a more complex syntax, a translator is needed to explain this language to the machine.

COMPUTER PROGRAMA computer program is a set of commands that tells the CPU what to do. Software may contain only an executable program file, or it may have several other supporting files such as: Link Libraries Initialization of files Help files

PROGRAM INSTRUCTIONS

Points to be considered while writing instructions. Reliability, Maintainability, Portability, Readability, Performance, Storage Saving.