A-Level AQA Computer Science Paper 2
Baud Rate >>> The maximum possible number of signal changes that can occur in a wire per second.
Bit Rate >>> The number of bits that can be sent down a wire per second.
Integer >>> A whole number that can be positive, negative or zero.
Examples: -3, 0, 7, 2013588.
Natural (Number) >>> A whole number that is either positive or zero.
Examples: 0, 1, 2, 100, 67238.
Rational (Number) >>> Any number that can be represented as the fraction 'a/b' where 'a' and 'b' are
both integers.
Examples: -0.2, 4/5, 1, 1/3.
Irrational (Number) >>> Any number that cannot be represented as a fraction.
Examples: square root of 2, PI.
Real (Number) >>> Any number that can either be rational or irrational.
Boolean >>> A value that is either true or false.
String >>> A series of characters.
Array >>> A variable that can store multiple values of the same data type.
Example: Storing the high-scores of a game as integers.
Record >>> A variable that can store multiple values that can have different data types.
,Example: Storing data about a book; a string for the title, an integer for the number of pages, etc.
Variable >>> A metaphor for it is that is a box that can store a specific type of item (the data type) and
has a name assigned to it (the identifier). Its value can be changed during run-time of the program.
Constant >>> A metaphor for it is that is a box that can store a specific type of item (the data type) and
has a name assigned to it (the identifier). Its value cannot be changed during run-time of the program.
Subroutine >>> This can be broken down into procedures and functions.
Procedure >>> A block of code that performs a specific task that does not return a value. Parameters
can be passed into it.
Function >>> A block of code that performs a specific task that returns a value. Parameters can be
passed into it.
Selection >>> This is when an if statement or select case is used to, for example, check the value of a
variable.
Iteration >>> This is when, within the program, there is a loop.
Definite Iteration >>> The number of times that the program will loop is already specified.
Example: For loop.
Indefinite Iteration >>> The number of times the program will loop is unknown.
Example: Do loop.
Nested (structures) >>> This is when either iterative or selective statements are put inside of each
other.
Meaningful Identifiers >>> Subroutines, variables and objects should have sensible names.
Real Division >>> Finds the value (usually as a decimal) of one number divided by another.
Integer Division >>> Finds the integer part of one number divided by another.
Integer Remainder >>> Finds the remainder of one number divided by another.
Truncation >>> Chops the decimal part off a number.
Floor >>> Rounds a number down to the nearest integer.
, Ceiling >>> Rounds a number up to the nearest integer.
AND >>> Logical Operation:
Returns true only when both values are true.
OR >>> Logical Operation:
Returns true as long as at least one of the values are true.
XOR >>> Logical Operation:
Returns true only when exactly one of the two values is true and not both.
NOT >>> Logical Operation:
Returns true if the value is false and returns false if the value is true.
Exception Handling >>> When a try catch is used in the program to deal with any errors that may occur.
ByVal >>> When a variable is passed into a subroutine as a copy so its value will not be changed.
ByRef >>> When a variable is passed into a subroutine as a reference so its value can be changed.
Local (Variable) >>> A variable that is defined, for example, within a subroutine and cannot be viewed
or modified from outside of the block of code is was declared in.
Global (Variable) >>> A variable that is declared, usually at the start of the program, and can be
accessed and modified from anywhere at all in the program.
Recursion >>> A subroutine's definition contains a self-call meaning a function or procedure calls itself
as a way of performing iteration.
Object-Oriented (Programming) >>> A type of programming paradigm when multiple objects are
created and handled to run the program.
Example: In a game you might have an object for the player and then multiple objects for the enemies.
Procedural (Programming) >>> A type of programming paradigm when you break down a project,
usually using a decomposition diagram, into individual tasks which can each be performed by a
procedure.
Functional (Programming) >>> A type of programming paradigm that is mainly used for calculations. No
variables are declared, only functions are used with parameters and return statements.
(Object) Instantiation >>> When an object is first created using the 'new' keyword.
Baud Rate >>> The maximum possible number of signal changes that can occur in a wire per second.
Bit Rate >>> The number of bits that can be sent down a wire per second.
Integer >>> A whole number that can be positive, negative or zero.
Examples: -3, 0, 7, 2013588.
Natural (Number) >>> A whole number that is either positive or zero.
Examples: 0, 1, 2, 100, 67238.
Rational (Number) >>> Any number that can be represented as the fraction 'a/b' where 'a' and 'b' are
both integers.
Examples: -0.2, 4/5, 1, 1/3.
Irrational (Number) >>> Any number that cannot be represented as a fraction.
Examples: square root of 2, PI.
Real (Number) >>> Any number that can either be rational or irrational.
Boolean >>> A value that is either true or false.
String >>> A series of characters.
Array >>> A variable that can store multiple values of the same data type.
Example: Storing the high-scores of a game as integers.
Record >>> A variable that can store multiple values that can have different data types.
,Example: Storing data about a book; a string for the title, an integer for the number of pages, etc.
Variable >>> A metaphor for it is that is a box that can store a specific type of item (the data type) and
has a name assigned to it (the identifier). Its value can be changed during run-time of the program.
Constant >>> A metaphor for it is that is a box that can store a specific type of item (the data type) and
has a name assigned to it (the identifier). Its value cannot be changed during run-time of the program.
Subroutine >>> This can be broken down into procedures and functions.
Procedure >>> A block of code that performs a specific task that does not return a value. Parameters
can be passed into it.
Function >>> A block of code that performs a specific task that returns a value. Parameters can be
passed into it.
Selection >>> This is when an if statement or select case is used to, for example, check the value of a
variable.
Iteration >>> This is when, within the program, there is a loop.
Definite Iteration >>> The number of times that the program will loop is already specified.
Example: For loop.
Indefinite Iteration >>> The number of times the program will loop is unknown.
Example: Do loop.
Nested (structures) >>> This is when either iterative or selective statements are put inside of each
other.
Meaningful Identifiers >>> Subroutines, variables and objects should have sensible names.
Real Division >>> Finds the value (usually as a decimal) of one number divided by another.
Integer Division >>> Finds the integer part of one number divided by another.
Integer Remainder >>> Finds the remainder of one number divided by another.
Truncation >>> Chops the decimal part off a number.
Floor >>> Rounds a number down to the nearest integer.
, Ceiling >>> Rounds a number up to the nearest integer.
AND >>> Logical Operation:
Returns true only when both values are true.
OR >>> Logical Operation:
Returns true as long as at least one of the values are true.
XOR >>> Logical Operation:
Returns true only when exactly one of the two values is true and not both.
NOT >>> Logical Operation:
Returns true if the value is false and returns false if the value is true.
Exception Handling >>> When a try catch is used in the program to deal with any errors that may occur.
ByVal >>> When a variable is passed into a subroutine as a copy so its value will not be changed.
ByRef >>> When a variable is passed into a subroutine as a reference so its value can be changed.
Local (Variable) >>> A variable that is defined, for example, within a subroutine and cannot be viewed
or modified from outside of the block of code is was declared in.
Global (Variable) >>> A variable that is declared, usually at the start of the program, and can be
accessed and modified from anywhere at all in the program.
Recursion >>> A subroutine's definition contains a self-call meaning a function or procedure calls itself
as a way of performing iteration.
Object-Oriented (Programming) >>> A type of programming paradigm when multiple objects are
created and handled to run the program.
Example: In a game you might have an object for the player and then multiple objects for the enemies.
Procedural (Programming) >>> A type of programming paradigm when you break down a project,
usually using a decomposition diagram, into individual tasks which can each be performed by a
procedure.
Functional (Programming) >>> A type of programming paradigm that is mainly used for calculations. No
variables are declared, only functions are used with parameters and return statements.
(Object) Instantiation >>> When an object is first created using the 'new' keyword.
