1.2.2 - Applications Generation

Question 1

What is the characteristic of Closed-Source software? [2]

Answer 1

Source code is not freely available [1]. It is developed and provided to the user as a fully compiled [1]

Question 2

What is the characteristic of Open-Source software? [2]

Answer 2

The source code is freely available… [1] to edit / amend recompile [1]

Question 3

Explain the benefits to the users of the software being open source [3]

Answer 3

Free of cost. [1] Code open for bugs to be spotted and fixed. [1] Can tailor the program to their specific needs. [1]

Question 4

What are the difference between open source and closed source software? [4]

Answer 4

Open source has the source code freely available…[1] to copy/recompile [1]. Close sourcecode is not made available… [1] There are licensing conditions restricting the redistribution [1]

Question 5

Describe what is meant by the term utility software? [2]

Answer 5

A piece of software with one purpose. [1] usually to do with the upkeep / maintenance of a computer.[1]

Question 6

State how an application differs from a utility. [2]

Answer 6

Application performs tasks for the user [1] Utility performs genereic tasks [1]

Question 7

What is a Compiler? [3]

Answer 7

A group of programs [1] utilised to generate [1] and (often) optimise object code [1]

Question 8

What are the 4 stages of Compilation? [4]

Answer 8

Lexical Analysis [1] Syntax Analysis [1] Code Generation [1] Code Optimisation [1]

Question 9

What happens during the Lexical Analysis stage? [3]

Answer 9

The Comments and Whitespaces are removed [1] Variable Names are added to a symbol table [1] Reserved words (such as while) are tokenized [1]

Question 10

What happens during the Syntax Analysis stage? [3]

Answer 10

The code is checked to ensure it follows the rules of the language [1] Often by placing the tokens into a (abstract syntax) tree [1] Errors are generated where the language rules are broken [1]

Question 11

What happens during the Code Generation stage? [2]

Answer 11

The object/machine code is created [1] This code may be inefficient [1]

Question 12

What happens during the Code Optimisation stage? [2]

Answer 12

Redundant/Repeated Code is identified [1] and is rearranged or removed [1]

Question 13

Why is the Lexical Analysis Stage necessary? [1]

Answer 13

To put the code into a format which can be read and processed by the syntax analyser [1]

Question 14

Why is the Syntax Analysis Stage necessary? [1]

Answer 14

To ensure the code is valid and will run [1]

Question 15

Why is the Lexical Analysis Stage necessary? [1]

Answer 15

To put the code into a format that the processor can understand [1]

Question 16

Why is the Lexical Analysis Stage necessary? [1]

Answer 16

Not necessary; ensures the code works quicker/using less memory [1]

Question 17

What is a Linker? [3]

Answer 17

A utility [1] program used during Compilation [1] that links object files (contain object code) [1]

Question 18

What is a Loader? [3]

Answer 18

Part of an operating system [1] that is responsible for loading programs and libraries [1] by copying the executable code into the RAM [1]

Question 19

What is a Library? [2]

Answer 19

a collection code used by computer programs [1] (often) for software development [1]

Question 20

What do application softwares do? (3)

Answer 20

It accepts user input (1) It processes user input according to algorithms implemented in the code (2) It generates output (3)

Question 21

What is general purpose software?

Answer 21

Software that can be used for a variety of tasks. They attract many users and so can be sold cheaply.

Question 22

What is special purpose software?

Answer 22

Software that can be used for one particular task. More expensive because they are only purchased by users who need that particular functionality.

Question 23

What is bespoke software?

Answer 23

software that is developed to meet the user’s specific requirements.

Question 24

High-Level Languages

Answer 24

They are are used to write programs that are independent of the computer architecture they will run on. They are compiled/interpreted.

Question 25

Compiler

Answer 25

Reads the whole the code then translates it to machine code.

Question 26

Advantages of Compiler

Answer 26

translates the entire code code has to be compiled once. The user doesn’t need a translator to install it. Code can be optimised for the compiler. Compiled code can be distributed as machine code.

Question 27

Disadvantages of Compiler

Answer 27

won’t compile if there is an error. Code needs to be recompiled for different chipsets.

Question 28

Interpreter

Answer 28

They translate and execute each line of source code. Each program line when run is first syntax-checked. If a syntax error is found the program halts. Following the syntax check each line of source code is converted into machine code and executed. If a runtime error occurs the program crashes.

Question 29

Advantages of Interpreter

Answer 29

Machine independent. They work with high-level languages. It runs until it hits an error. Debugging is quicker and easier as errors are reported in the console which shows what and where the error is in the code

Question 30

Disadvantages of Interpreter

Answer 30

Some parts of the code may never run. Bad for shipping code. Runs more slowly because each time the program is run it must be translated all over again. The program needs an interpreter to run.

Question 31

Bytecode

Answer 31

Most interpreted languages now use bytecode as an intermediate stage to speed up the translation process. The source code is compiled to produce bytecode (low-level code) which is interpreted by a virtual machine.

Question 32

Assembler

Answer 32

Assemblers translate assembly mnemonics into executable code.

Question 33

Difference between an application software and a utility (2)

Answer 33

Application performs tasks for the user (rather than computer). Utility performs generic (rather than specific)tasks.

Question 34

Describe what is meant by JavaScript (2)

Answer 34

A programming language that runs in a web browser (1) that can be embedded into HTML (1) with tag (1) to add interactivity to a page (1).

Question 35

Explain why it is usually the case that JavaScript is interpreted rather than compiled (2)

Answer 35

JavaScript is likely to be run on a variety of machines (1) with different processors / architectures (1). Compiled code is machine dependent (1) whereas interpreters run on high level code (1) which is machine independent (1).

Question 36

Explain why all closed source software is most likely to be compiled rather than run on an interpreter (2)

Answer 36

Compilers translate the source code prior to distribution meaning the user gets an executable program (which makes amending of the program much more difficult). Interpreters translate source code every time the program is run meaning the user needs the source code to run the program.

Question 37

Describe what is meant by the term ‘assembler’ (2)

Answer 37

A program that translates assembly code (1) into machine code/object code (1)