5: Application Generation

Question 1

What is hardware?

Answer 1

All physical parts of a computer system and its related devices, both internal and external

Question 2

What is software?

Answer 2

General term covering all computer programs. Often falls into broad categories such as application, system and utility software

Question 3

Examples of common categories of application software?

Answer 3

• Word processor
• database
• Web browser
• Graphics manipulation

Question 3

Examples of common categories of application software?

Answer 3

• Word processor
• database
• Web browser
• Graphics manipulation

Question 4

Examples of common categories of application software?

Answer 4

• Word processor
• database
• Web browser
• Graphics manipulation

Question 5

Examples of common categories of application software?

Answer 5

• Word processor
• database
• Web browser
• Graphics manipulation
• Spreadsheets
• email clients

Question 6

Give an example of a generic application

Answer 6

• a word processor is a generic application
• It does not have a specific or narrow purpose
• You can use it to carry out different tasks and meet multiple needs (eg writing a letter, essay, report, guest list, invite)

Question 7

Give an example of a specific application

Answer 7

• Database software is an example of a specific application
• beyond creating, managing and using a database, it has little use
• As a result of being so specific, it is almost essential for creating a serious database application

Question 8

What is the purpose of utility software?

Answer 8

Utility software is designed to:
- Keep your computer safe
- Keep it running efficiently
- Provide you with useful tools to manage your files and applications

Question 9

What are some different types of utility software?

Answer 9

• file repair
• backup
• compression
• defragmentation
• anti-malware
• file management
• device drivers

Question 9

What are some different types of utility software?

Answer 9

• file repair
• backup
• compression
• defragmentation
• anti-malware
• file management
• device drivers

Question 10

What does file repair software do?

Answer 10

• Files can become corrupt or damaged for a number reasons
• File repair software attempts to correct these issues and restore the file to its original working state
• A file repair facility can be built into applications as well as being a separate dedicated software tool in the operating system

Question 11

What does backup software do?

Answer 11

• Backups can be set up to be manual, automatic or scheduled
• You can perform full backups or incremental backups
• You can back up to different media or an off-site cloud system
• Comes with operating system but can be purchased separately

Question 12

What does data compression software do?

Answer 12

• Reduces the size of a file so it takes up less space and downloads faster over the internet

Question 13

What does defragmentation software do?

Answer 13

• reorganises files on a hard disk, putting fragments of files and free space back together
• This reduces the movement of the read/write head across the surface of the disk, which speeds up file access

Question 14

What does anti-malware software do?

Answer 14

helps keep your computer and files safe from many types of malware including viruses, trojans, woms and spyware

Question 15

What is open source software?

Answer 15

• users can modify and distribute the software
• can be installed on any number of computers
• support provided by the community
• users have access to the source code
• may not be fully tested

Question 16

What are the pros of open source software for the user?

Answer 16

• software is free
• wide community modification

Question 17

What are the cons of open source software for the user?

Answer 17

• can be poorly supported
• some features might not be well tested

Question 18

What are the pros of open source software for the creator?

Answer 18

Gets their software out there to a wider community

Question 19

What are the cons of open source software for the creator?

Answer 19

Little to no financial gain

Question 20

What is closed source software?

Answer 20

• Protected by the Copyrights, Design and Patents Act
• Users cannot modify the software
• Usually paid for and licensed per user or per computer
• Supported by developers who do not release source code
• tested by developers prior to release although it may run beta programs

Question 21

What are pros of closed source software for the user?

Answer 21

Well supported, tested and professional built product

Question 22

What are the cons of closed source software for the user?

Answer 22

Cost or ongoing subscription fee

Question 23

What are the pros of closed source software for the creator?

Answer 23

They receive an income for their product

Question 24

What are the cons of closed source software for the creator?

Answer 24

- Constant demand from community for more features and improvements - Piracy issues

Question 25

What is source code?

Answer 25

- Programming language humans use - Descriptive and easy to use for us to understand, read, maintain and debug

Question 26

What is machine code?

Answer 26

- Pure binary form of source code - Machines need to convert source code into machine code to be able to understand and execute it

Question 27

What is translation?

Answer 27

The process of converting source code into machine code

Question 28

What does an assembler do?

Answer 28

- Translates assembly language into machine code - takes basic commands and operations from assembly code and converts them into binary code that can be recognised by a specific type of processor - the translation process is typically a one-to-one process from assembly code to machine code

Question 29

What are the advantages of using an assembler?

Answer 29

- Programs written in machine language can be replaced with mneumonics, which are easier to remember - memory efficient - speed of execution is faster - hardware-oriented - requires fewer instructions to accomplish the same result

Question 30

What are the disadvantages of using an assembler?

Answer 30

- Long programs cannot be executed on small computers - It takes a lot of time to code or write the program, as it more complex in nature - Difficult to remember the syntax

Question 31

What is a compiler?

Answer 31

- translates source code from high-level languages into object code and then machine code to be processed by the CPU. - The whole program is translated into machine code before it is run.

Question 32

What are the advantages of using a compiler?

Answer 32

- no need for translation at runtime - speed of execution is faster - code is usually optimised - original source code is kept secret

Question 33

What are the disadvantages of using a compiler?

Answer 33

- program will not run with syntax errors, which will make it more difficult to write the code - needs to be recompiled when code is changed - designed for a specific type of processor

Question 34

What is an interpreter?

Answer 34

- translates source code from high-level languages into machine code, ready to be processed by the CPU - the program is translated line-by-line as the program is running

Question 35

What are the advantages of using an interpreter?

Answer 35

- Easy to write source code, as the program will always run, stopping when it finds a syntax error - Code does not need to be recompiled when code is changed - It is easy to try out commands when the program has paused after finding an error - this makes interpreted languages very easy for beginner programmers to learn to write code

Question 36

What are the disadvantages of using an interpreter?

Answer 36

- Translation software is required at runtime - Speed of execution is slower - Code is not optimised - Source code is required

Question 37

What are the 4 stages of compilation?

Answer 37

- Lexical analysis - Syntax analysis - Code generation - Code optimisation

Question 38

What happens during lexical analysis?

Answer 38

- Comments and whitespace are removed - Remaining code turned into a series of tokens - Symbol table is created to keep track of variables and subroutines

Question 39

What happens during syntax analysis?

Answer 39

- abstract syntax tree is built from tokens produced in the previous stages - errors generated if any tokens break the rules of the language

Question 40

What happens during code generation?

Answer 40

- abstract code is converted to object code - object code is the machine code produced before the linker is run

Question 41

What happens during code optimisation?

Answer 41

- Tweaks the code so it will run as quickly as possible and use as little memory as possible

Question 42

What is a library?

Answer 42

- ready-compiled and tested that can be run when needed

Question 43

What are the benefits of using libraries?

Answer 43

1. pre-compiled: so they are typically optimised to run quickly 2. pre-tested: so you can be relatively sure they are already free from errors 3. Quick and easy to use and hook into your code

Question 44

What are drawbacks of using libraries?

Answer 44

- Adding functionality can be difficult - You have to trust that the developers will continue to maintain the library

Question 45

What is the linker responsible for?

Answer 45

- Putting the appropriate machine addresses in all the external call and return instructions so all modules and external library routines are linked together correctly - links any separately compiled subroutines into the object code

Question 46

What is static linking?

Answer 46

- All the required code from the libraries is included directly in the finished machine code - this can result in large executable program files

Question 47

What is dynamic linking?

Answer 47

- Compiled versions of the required libraries are stored on the host computer - The operating system links the required code from the library as the program is running - This cuts down on the size of the compiled machine code, but if the dynamic libraries change, the program may stop because it tries to call a subroutine in the wrong way

Question 48

What is the loader?

Answer 48

- part of the operating system that loads the executable program file into memory, ready to be run - when using dynamic linking, it will also be responsible for loading the required libraries into memory.