Application Generation

Question 1

applications definition

Answer 1

a program that can be run on a computer, allowing the user to carry out specific tasks

Question 1

assembler definition

Answer 1

a translator in low level language, which converts assembly language into machine code

Question 2

closed source definition

Answer 2

proprietary software sold with a license and restrictions on usage and how many users can use it

Question 3

code generation definition

Answer 3

the third and final stage of compilation, where an equivalent machine code program is produced

Question 4

compilation definition

Answer 4

the process of analysing high level language source code and converting it into machine code

Question 5

compliers definition

Answer 5

a translator that converts high level language to machine code

Question 6

interpreters definition

Answer 6

a translator which checks a source program for syntax errors line by line, translates it to machine code and executes the line

Question 7

lexical analysis definition

Answer 7

the first stage of compilation, where extra spaces and comments are removed from source code and it is searched for simple errors.

keywords, constants and variables are replaced by tokens

variable names are loaded into the symbol table

Question 8

libraries definition

Answer 8

a collection of programs which are already compiled and can be loaded into a program and run whenever required

Question 9

linkers definition

Answer 9

a program which places the appropriate machine addresses in the call and returns instructions of a compiled program so all the other required object code files and modules are linked together

Question 10

loaders definition

Answer 10

a program that loads the executable object program and its associated libraries into memory before it is run

Question 11

open source definition

Answer 11

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

Question 12

optimisation definition

Answer 12

during code generation, the object code is made as efficient as possible by removing redundancies to produce code that gives the same result

Question 13

syntax analysis definition

Answer 13

the second stage of compilation, where statements, expression and tokens are checked for syntax errors using syntax diagrams

Question 14

translator definition

Answer 14

a program which converts code from one computer language to another

Question 15

utilities definition

Answer 15

system software with a specific purpose usually related to maintenance such as optimising the performance of the computer, diagnosing issues, backing up files, setting up firewalls etc.

Question 16

what is the difference between applications and systems software

Answer 16

applications software is utilised directly by the end-user whereas systems software ensures the high performance of the computer

Question 17

give 3 examples of utilities

Answer 17

• compression
• disk defragmentation
• antivirus
• automatic backup
• automatic updating

Question 18

give one advantage of using closed source code

Answer 18

• thorough, regular and well-tested updates
• expert support and user manuals from company
• high levels of security as it is developed in a professional, controlled environment

Question 19

state two features of open source code

Answer 19

• does not require a license to be used
• distributed with the source code
• can be modified and sold on

Question 20

give two advantages of using compiled code over interpreted code

Answer 20

• faster to execute
• does not require compiler to run

Question 21

give two advantages of using interpreted code over compiled code

Answer 21

• is platform independent
• runs instantly without time waiting for compilation
• useful for debugging

Question 22

what is assembly language

Answer 22

a low-level language that has almost a one-to-one relationships with machine code

it is platform specific

Question 23

what are the stages of compilation

Answer 23

lexical analysis
syntax analysis
code generation
optimisation

Question 24

what happens during syntax analysis

Answer 24

- tokens are compared to the rules of the programming language - syntax errors are identified - symbol table updated with more details - semantic analysis (finding logic errors)

Question 25

what are the similarities and differences between static and dynamic linkers

Answer 25

similarities: both link external modules and libraries to main program static: library code copied into the file file size increased dynamic: addresses of libraries included within file external updates automatically feed through to main program

Question 26

give three advantages of using libraries

Answer 26

- error-free - save time - re-usable - no need to 'reinvent the wheel' - designed by experts

Question 27

describe the function of a loader

Answer 27

provided by the operating system, a loader retrieves the library or subroutine from the given memory location

Question 28

what is the purpose of the optimisation stage of compilation

Answer 28

- reduce execution time - reduce inefficient sections of code - remove redundant code

Question 29

what is compression

Answer 29

operating systems provide utilities that enable files to be compressed and decompressed this is used when compressing large files to be transmitted across the internet and is commonly used to compress scanned files

Question 30

what is disk defragmentation

Answer 30

as the hard disk becomes full, read/write times slow down this is because files become fragmented as they are stored in different parts of memory the disk defragmenter utility rearranges the contents of the hard drive so they can be accessed faster, thus improving performance

Question 31

what is antivirus

Answer 31

antivirus is responsible for detecting potential threats to the computer, alerting the user and removing these threats

Question 32

what is automatic updating

Answer 32

this utility ensures the operating system is kept up to date, with any updates being automatically installed when the computer is restarted updates tackle bugs or security flaws so this ensures the system is less vulnerable to malware and hacking threats

Question 33

what is automatic backup

Answer 33

the backup utility automatically creates routine copies of specific files selected by the user how often files are backed up is also specified by the user this means that in the event of a power failure, malicious attack or other accident, files can be recovered

Question 34

what is the stages of compilation for

Answer 34

when a compiler is used, high-level language goes through four stages before it is turned into object code that is ready to be executed

Question 35

what are static linkers

Answer 35

modules and libraries are added directly into the main file this increases the size of the file any updates to the module and libraries externally will not affect the program this means a specific version of a library can be used

Question 36

what are dynamic linkers

Answer 36

addresses of modules and libraries are included in the file where they are referenced when the program is run, the loader retrieves the program at the specified address so it can be executed the advantage here is that files remain small and external updates feed through to the main file; there is no need to rewrite the code