Computing a-level

AQA

[C#] switch case statement definition

a form of selection where the options are constant

[C#] symbol for XOR

^

[C#] first line of a switch case statement

switch(variable){

[C#] Code for a case 1 of a case statement

case 1: code break;

[1] Decomposition

breaking something down into its atomic parts

[1] abstraction

removing all unnecessary data

inheritance

adding your own cade to someone elses

[1] polymorphism

one thing can do many different things dependent on the situation

examples of primitive datatypes

bool,int,string

[1] negative of arrays

cannot change there shape and only hold 1 datatype

[C#] declaring a list

list<int> myIntList = new List<int>()

[C#] Methods for lists

.Add().Remove().RemoveAt().IndexOf().RemoveAll()

[C#] Properties of lists

.Count, Index[int32]

[C#] delclaring a list with data

List<int> myIntList = new List<int>{1,2,3};

[7] when to use lists

when the size needs to be variable and the order of the elements is irrelevant but indexable

[7] Mechanics of stacks

LIFO

[7] what do stacks, queues and dictionaries not have

an index

[C#] Methods in Stacks

.IsEmpty,IsFull().Push().Pop().Peek().Count()

[7] Mechanics of Queues

FIFO

[C#] Methods in Queues

.Enqueue().Dequeue().Peek().Count()

[1] example of counting iteration

for

[1] example of conditional iteration

while,do-while

[1] scope definition

the range in which a variable or parameter exists

[1] how are non-primitive datatypes automatically passed

by reference

[7] What is a dictionary

it hold 2 pieces of data with different datatypes

[7] 1st part of a dictionary

key

[7] 2nd part of a dictionary

value

[1] Call stack definition

stores information about the active subroutines in a program

[1] recursion definition

a subroutine that calls itself

[1] static datatype definition

cannot grow in size

[1] dynamic datatype definition

can grow in size e.g. lists

[7] how is a list stored

it is stored as an array and the copies all items when an item is added and moves to a different place

[1] what do stack frames do

each one contains information for one subroutine

[1] what do stack frames contain

return address, local variable, local parameters

[1] what happens when too many subroutine calls are pushed

stack overflow

[1] when is a subroutine recursive

when it is defined in terms of itself

[1] what must a recursive subroutine include

a stopping condition

[1] advantages of recursive coding

efficient, good for simple repetitive programs

[1] disadvantages of recursive coding

difficult to debug, could loop indefinitely, makes use of limited resource(call stack),uses more memory

[1] in OOP methods are seen as

behaviours

[1] in OOP subroutines are seen as

actions

[1] Instantiation

creating an object

[1] Inheritance OOP

classes can inherit data and behavours from parent classes

[1] what is the child class known as in OOP

subclass

[1] what is the parent class known as in OOP

superclass

[1] what do arrows look like in an inheritance diagram

unfilled arrow to parent class

[1] what is this

inheritance diagram

[1] what is this

inheritance class diagram

[1] Polymorphism

a languages ability to process objects differently depending on their class

[1] what is method overriding (polymorphism)

a form of runtime polymorphism in which a subclass provides a specific implementation of a method that is already defined in its superclass.

[1] what is runtime polymorphism

polymorphism which occurs when the program is run

[1] what is Method overloading (polymorphism )

a form of static polymorphsim where multiple methods in the same class have the same name but a different number of parameters.

[1] example of method overloading

Random.Next(10) Random.Next(1,10)

[1] what is a poplymorphic array

an a array containing objects of different classes that inherit from the same superclass

[1] encapsulation

when an objects behaviors and state is defined in a single entity so it doesn’t affect other objects functions

[1] what does private do

an objects instance variables are hidden so they must use messages to access the data

[1] what has access to private code

members of the same class

[1] what has access to public code

all of the program

[1] what has access to protected code

members of the same class and its derived classes

[1] Association OOP

an object containing another object

[1] Compostion OOP

if the containing object is destroyed so are the objects it contains

[1] Aggregation

the objects remain when their container object is destroyed

[1] what does this show

aggregation

[1] what does this show

compostion

[3] what is 4 bits

a nibble

[3] what is 2 nibbles

a byte

[3] kibi

2^10

[3] mebi

2^20

[3] gibi

2^30

[3] tebi

2^40

[3] What is a parity bit

an extra bit added to binary data to ensure that the total number of 1s in the data is even or odd

[3] name 4 transmission errors

parity bit,majority voting, check digit, check sum

[3] what is majority voting

what the majority of computers think is true

[3] what is a check sum

adding all of the data and seeing if it matched the record

[3] what does one left bit shift do

2x

[3] absolute error definition

the difference in the number you got vs. the actual result

[3] relative error formula

((true-result)/true)x100

[3] what is the relative error more useful

its impact is relative to what it is being compared to

[3] why do we use floating point in normalised form

to maximise precision and maximise accuracy

[3] what is standard screen resolution

72 dpi

[3] standard print quality resolution

300 dpi

[3] resolution formula

widthxheight

[3] colour depth defintion

number of bits stored for each pixel

[3] resolution definition

number of pixels per inch

[3] image file size formula

colour depth x size(wxh)

[3] metadata definition

data about data which is stored in the same file as the image data

[3] examples of metadata

-date is was created, - width and height in pixels, - colourdepth, GPS coordinates, - author

[3] what are vector graphics

images created using mathematical equations that define shapes such as lines, curves, and polygons, rather than using pixels. This allows them to be scaled infinitely without loss of quality

[3] advantages of vector graphics

no loss of quality , image can change size and shape and will stay crisp

[3] disadvantage of vector graphics

low accessibility(only some programs can use it )

[3] data stored in each object of a vector graphic

shape type, fill colour, length, width, radius, position, line colour and weight

[3] ADC meaning

analogue to digital converter

[3] DAC meaning

digital to analogue converter

[3] sampling definition

data measured at regular intervals

[3] what does increasing sample resolution in sound do

increase bit depth for voltage storage therefore increase file size

[3] what is sample rate measured in

Hertz

[3] what does increasing the sample rate do

increase accuracy and file size

[3] sound file size formula

sample rate x resolution x length(secs)x(stereo/mono)

[3] Nyquist theorem

sample frequency must be greater than 2x the max frequency plus a little more

[3] what is the max hearing frequency of humans

about 22khz