2.2 Applications Generation

Question 1

What are 2 types of software?

Answer 1

applications software
systems software

Question 2

What is applications software?

Answer 2

Software designed to be used by the end-user in order to perform specific tasks.

Question 3

What are some examples of applications software?

Answer 3

desktop publishing
word processing
spreadsheets
web browsers
graphics design

Question 4

What is systems software?

Answer 4

Low-level software that is responsible for interacting with hardware and providing a platform for applications software to run on.

Question 5

What are some examples of systems software?

Answer 5

library programs
utility programs
operating system
device drivers

Question 6

What is utility software?

Answer 6

Systems software that has a specific function linked to the maintenance and upkeep of the operating system.

Question 7

What are some examples of utilities?

Answer 7

compression software
defragmentation software
antivirus software
backup software
device drivers

Question 8

What does compression software do?

Answer 8

Compresses/decompresses files. Compression of files increases file transfer speeds and reduces the storage space they take up by removing unnecessary data.

Question 9

What does disk defragmentation software do?

Answer 9

Rearranges the contents of the hard drive so that programs are stored contiguously and there are blocks of free space. This speeds up read/write times.

Question 10

What does antivirus software do?

Answer 10

Detects potential threats to the computer, alerts the user and removes them.

Question 11

What does backup software do?

Answer 11

Creates copies of important files in case they are lost during a malicious attack or power cut.

Question 12

What is open source software?

Answer 12

Software where the source code is distributed with the program and available for anyone to use.

Question 13

What is closed source software?

Answer 13

Software where the source code is privately owned and you must hold an appropriate license to use the software.

Question 14

What are the advantages of open source software?

Answer 14

can be modified and improved by anyone

can be modified and sold on or modified to your own specific needs

technical support from online community

Question 15

What are the disadvantages of open source software?

Answer 15

online support may be insufficient or incorrect

lower security as the software isn’t developed in a controlled environment

Question 16

What are the advantages of closed source software?

Answer 16

typically well tested and regular updates

company that owns the software may provide user manuals and expert support

high levels of security as developed in a professional environment

Question 17

What are the disadvantages of closed source software?

Answer 17

license may restrict how many people can use the software at once

users cannot modify the software to their individual needs

Question 18

What is a translator?

Answer 18

A program that converts high level source code into low level machine/object code which can be executed by the computer.

Question 19

What are 3 types of translator?

Answer 19

compiler
interpreter
assembler

Question 20

How do compilers work?

Answer 20

They translate the high level code into an executable file made up of machine code all at once.

Question 21

What are the advantages of compilers?

Answer 21

the executable file can be ran without a translator

the executable file can be ran quickly many times as there is no need for further translation

Question 22

What are the disadvantages of compilers?

Answer 22

initial compilation process may take long and doesn’t execute the code

if changes are made to the source code, the whole program must be recompiled

the executable file can only be run on certain devices as the machine code is specific to computer architecture

Question 23

How do interpreters work?

Answer 23

Translate and execute code line by line and stop and produce an error message if necessary.

Question 24

What are the advantages of interpreters?

Answer 24

Instantly compile code

useful for testing code and pinpointing errors

code can be executed on a range of platforms as long as the right interpreter is available so the code is more portable

Question 25

What are the disadvantages of interpreters?

Answer 25

code must be translated every time its executed

code requires an interpreter in order to run

Question 26

What do assemblers do?

Answer 26

Translate assembly code to machine code on a (almost) line to line basis.

Question 27

What is assembly code?

Answer 27

Low level code that is the ‘next level up’ from machine code. This code is still specific to computer architecture and the processor’s instruction set.

Question 28

What are the 4 stages of compilation?

Answer 28

lexical analysis
syntax analysis
code generation
optimisation

Question 29

What happens during lexical analysis?

Answer 29

input - source code

comments and whitespace are removed

variables and subroutines are stored in a symbol table

keywords are converted into a series of tokens

output - series of tokens and symbol table

Question 30

What happens during syntax analysis?

Answer 30

input - series of tokens and symbol table

code is checked to ensure it follows the syntax rules of the language

tokens are used to produce an abstract syntax tree

if any syntax rules are broken, errors are reported and the compilation process stops

output - abstract syntax tree and symbol table

Question 31

What happens during code generation and optimisation?

Answer 31

object/machine code is generated from the abstract syntax tree

redundant parts of code are detected and removed to make the code take up less space in memory

repeated sections of code may be grouped and replaced to make the code execute faster

Question 32

What is a library?

Answer 32

A precompiled external program that can be incorporated within other programs.

Question 33

What are the advantages of libraries?

Answer 33

typically ready to use and error free

saves time developing and testing modules of code

can be reused within multiple different programs

Question 34

What are the disadvantages of libraries?

Answer 34

need to understand the different functions in the library and know their names

if the library contains bugs, you can’t fix them and must wait for the developers of the library to

Question 35

What is a linker?

Answer 35

A piece of software that is responsible for linking external libraries/modules that have been included within a program’s code.

Question 36

What is a loader?

Answer 36

A program that retrieves an external library from a given memory address.

Question 37

What are 2 types of linker?

Answer 37

static
dynamic

Question 38

How does a static linker work?

Answer 38

Libraries are directly added into the program increasing the file size but meaning external library updates will not impact the program as it uses a specific version.

Question 39

How does a dynamic linker work?

Answer 39

The address where a library is stored is added to parts of the program where the library is referenced. When the program is run, the loader retrieves the library so that the code can be executed.