S R Computer Institute

Set-4

1. the term hardware refers to the physical devices of a computer system thus input storage processing control and output devices are hardware
2. the term software refers to a collection of programs and associated documents
3. A program is a sequence of instructions written in a language understood by a computer it controls a computer’s processing activity and the computer performs precisely what the program wants it to do
4. A software package is a group of programs that solve a specific problem or perform a specific type of job
5. hardware and software of a computer must work together for the computer to produce useful output both hardware and software are necessary for a computer to do useful job
6. we classify most software into two categories system software and application software system software is a set of one or more programs which controls the operation and /or extends the processing capability of a computer system application software is a set of one or more programs which solves a specific problems or does a specific task
7. A few examples of systems software are operating systems programming language translators utility programs performance monitoring software and communications software
8. A few examples of application software are word processing software spreadsheet software graphics software personal assistance software education software and entertainment software
9. figure 10.1 shows the relationship among hardware system software application software and users of a computer system
10. firmware is software substituted for hardware and stored in a read only memory (ROM) chip
11. middle ware is a set of tools and data that helps applications use networked resources and services it is a separate software layer which acts as “glue” between client and server parts of an applications it provides a programming abstractions that masks the heterogeneity of underlying network hardware and operating system from application programmers
12. A user can acquire a desired software in one or more of the following ways:

(a) by buying pre-written software

(b) by ordering customized software

(c) by developing customized software

(d) by downloading public domain software

each of these ways of acquiring software has its own advantages and limitations

13. developing software putting it to use and maintaining it is a complex process involving following phases

(a) requirement specification

(b) system analysis and design

(c) implementation (also known as construction or code generation)

(d) testing and debugging

(e) deployment ( also known as installation )

(f) maintenance

Evolving software products through these phases is popularly known as software development life cycle (SDLC) model this model is also known as waterfall model

14. software engineering is systematic application of principles of computer science and mathematics in creation and building of cost- effective software solutions

15. To ensure that the instructions of a program are appropriate for the problem at hand in the correct sequence we must plan the program before writing it

16. The term algorithm refers to the log of a program it is a step-by-step description of how to arrive at a solution to a given problem

17. an algorithm represented in the form of a programming language is a program hence any programs is an algorithm but the reverse is not true

18. programmers often use flowcharts decision tables and pseudo codes for representing algorithms this helps them in developing effective and correct algorithms for their programs before coding them in programming languages

19. A flowchart is a pictorial representation of an algorithm programmers often use it as a program planning tool for visually organizing a sequence of steps necessary to solve a problem using a computer

20. Pseudo code is a program-planning tool that allows programmers to plan program logic by writing program instruction in a natural language such as english

21. structured programming is a more scientific approach to solving a programming problem by using only three basic logic (control) structures namely sequence logic selection logic and iteration (or looping) logic

22. structured programming helps in producing programs that are easy to understand and maintain it also helps in reducing program errors and the time spent in program testing

23. we use sequence logic for performing instructions one after another in sequence

24. we use selection logic for selecting a path out of two or more paths in program logic it uses three control structures called IF…. THEN , IF … THEN… ELSE, and CASE

25. we use iteration (or looping) logic for producing loops in programs logic when we need to execute one or more instructions several times depending on some condition it uses two control structures called do while and repeat until.