1.2.2 Applications Generations

Question 1

What is applications software?

Answer 1

designed to be used by end-user to perform one specific task.

• requires system software to run on
• eg. word processors, web broswers, database management software, spreadsheet

Question 2

What is systems software?

Answer 2

low-level software responsible for running computer system, interacts with hardware, platform for applications.

Question 3

utilities

Answer 3

piece of system software ensuring consistent performance of OS, maintains the OS

Question 4

compression

Answer 4

enables files to be compressed (reduced in size) so they can be transmitted over internet

Question 5

lossy compressions

Answer 5

compression that removes non-essential data from file, decrease in data integrity, data non-recoverable

Question 6

lossless compression

Answer 6

compression that retains all data in file by only storing instructions needed to reconstruct original file.

Question 7

disk defragmentation

Answer 7

as disk becomes full, read/write slower, as files become fragmented as stored in different parts of memory,

disk defragmenter rearranges contents of hard drive so it can be accessed faster, improving performance.

Question 8

antivirus

Answer 8

responsible for detecting potential threats to computer, alerts user and quarantines threats

Question 9

automatic update

Answer 9

ensures OS is kept uptodate, updates fix bugs ensure system is less vulnerable to malware

Question 10

backup

Answer 10

creates routine copies of specific files selected by user

Question 11

open source

Answer 11

software whose source code is freely available to view, redistribute and modify

Question 12

closed source

Answer 12

proprietary software, sold with a licence, source code unavailable

Question 13

translator

Answer 13

program that converts high-level source code in to low-level object code

Question 14

compiler

Answer 14

translates high level into machine code at once.

if changes need to be made, whole program must be recompiled

machine specific (specific to processor type and OS)

can be run without translator

Question 15

interpreter

Answer 15

translates and executes code line by line

slower than compiled as must be translated line by line

requires interpreter to run

Question 16

assembler

Answer 16

translates assembly code into machine code

each line assembly code = one line machine code

Question 17

assembly code

Answer 17

low level, platform specific, dependent on instruction set of processor

Question 18

lexical analysis

Answer 18

whitespace/comments removed, code analysed for keywords/variable names which are replaced by tokens.

Question 19

syntax analysis

Answer 19

tokens are analysed against grammar and rules of programming language, any tokens break rules are flagged as syntax errors. Abstract syntax tree produced (source code in a tree format). Semantic analysis carried, logic mistakes within program are detected.

Question 20

code generation

Answer 20

abstract syntax tree used to produce machine code

Question 21

optimisation

Answer 21

makes code faster to execute, more efficient. Redundant (unnecessary) parts of code removed. Repeated sections may be grouped. However, excessive optimisation may alter way program behaves.