Computer Science GCSE AQA Unit 1-4

High-level Programming languages

High-level Programming languages

Python, Visual Basic, C#, Java, C++, PHP, Delphi, Logo

Low-level Programming languages

Assembly language, machine code

Translation of Assembly Language

Assembly language programs must be converted to machine code for execution

Advantages of High-level Languages

Easier learning, faster coding, simpler debugging

Advantages of Low-level Languages

Faster execution, lower memory usage, hardware control

Translator Program

Converts one programming language to another

Types of Program Translators

Interpreter, Compiler, Assembler

Compiler Function

Translates high-level language to machine code

Source Code

Code written by the programmer

Interpreter Function

Converts high-level language to machine code

Assembler Function

Translates assembly code to machine code

Hardware

Physical components of a computer system

Software

Non-physical programs run on a computer system

Operating System (OS)

Manages computer hardware, users, and software resources

FETCH

Causes the next instruction to be fetched from main memory

DECODE

Decodes the instruction to determine its function

Clock Speed

Number of fetch-execute cycles per second

Number of Cores

Processing units on each CPU

Cache

Faster memory than RAM, slower than registers, often on CPU

EXECUTE

The instruction is carried out

Analogue sound signals

Continuous sound representations

Digital signals

Discrete sound representations

Sound digitization

Process of converting sound waves into digital form

Sampling rate

Number of sound samples taken per second

Sample resolution

Number of bits used to record each sound measurement

Lossy compression

Compression removing less audible sound data

Lossless compression

Compression without losing any data

RLE (Run Length Encoding)

Encoding method using frequency/data pairs for pixel runs

Huffman coding

Compression method based on letter frequency analysis

Truth table

Shows all output possibilities from Boolean inputs

Subroutines

Grouped code for repeated use under one name

Validation

Process of checking data for reasonableness

Verification

Double-checking data from an alternative source

Syntax error

Error in programming code grammar

Logic error

Error where code doesn't perform as intended

Character set

Set of symbols, letters, and digits a computer can represent

Bitmap image file formats

File formats like BMP, JPG, GIF, PNG, TIFF

Vector image file format

File format like SVG for scalable images

Image resolution

Pixel concentration in a specific area

Logic gates

Basic gates like AND, XOR, OR, NOT

Hardware

Physical components of a computer system

Software

Non-physical programs running on a computer system

Operating system

Software managing computer hardware and resources

Interrupts

Signals to CPU indicating immediate attention needed

Device driver

Program controlling peripheral devices

Memory Management

Copying programs from storage to main memory

Processor Management

Deciding program execution on processors

INTEGER

A whole number

REAL

A number with a decimal point

BOOLEAN

Can only be TRUE or FALSE

CHARACTER

A single alphabetic or numeric character

STRING

One or more characters enclosed in quote marks

algorithm

A specific set of instructions for solving a problem or completing a task

Abstraction

Removing unnecessary detail from a problem to focus on essential components

Decomposition

Breaking down a problem into smaller, more manageable ones

Add in c#

Subtract in c#

Divide in c#

/

Multiply in c#

Exponent in c#

^

Modulo in c#

% (the remainder)

Integer division in c#

You get the integer part of the division

A variable

A location in memory to store a value temporarily

A sequence

Series of steps completed one after the other

Selection

Choosing different paths through a program

Iteration

Repeating a part of a program, also known as looping

IF statement

A type of selection statement

FOR ... ENDFOR statement

A type of iteration statement

WHILE ... ENDWHILE statement

A type of iteration statement

REPEAT ... UNTIL statement

A type of iteration statement

Binary search

divides the list and checks the middle item.

Linear Search

Checking each item in a list sequentially