programming GCSe notes 2024

Data

unprocessed facts and figures

Information

Data that has been processed with 7

Bit

Either 1 or 0; Computer systems can only store and process Binary digits; 1 Character = 1 bit

Nibble

A group of 4 bits

Byte

8 bits

Kilobyte

Thousand (1002.4 bytes) à Base

Megabyte

Million

Gigabyte

Billion

Terabyte

Trillion

Petabyte

Quadrillion

Exabyte

Quintillion

Zettabyte

Sextillion

Yottabyte

Septillion

Strings

Textual data in form of a sequence of characters.

Numeric

Integers: Positive or negative whole number; Real: Positive or negative whole/decimal numbers

Character

Single letter or digit set up by computer

Date/time

Used to store data related to date or time.

Boolean

Can be yes/no, true/false, 1/0.

Resolution

Higher pixel number à Sharper image à More storage

Vector graphics

An image made using math and shapes; Can be resized without loss of clarity; File contains instructions on how to draw the image; Small file size

Bitmapped graphics

Made using pixels; Pixellated when resized; File contains individual pixels that make up the image; Higher resolution = more pixels; Large file size

Sample rate

Number of audio sound samples captured every second to represent the sounds digitally (measured in Hertz)

Bit rate

Quantity of data (kilobits per second (kbps)); Frequency × bit depth × channels = bit rate

Bit depth

Number of bits stored in each sound sample

Compression

Lowers required storage; Types of compression include Data compression, Lossy compression, Lossless compression

Buffer

Allocated in memory; Used to store a downloaded part of a video before it's watched

Analogue

Represents physical quantity; Continuous varying signal

Digital

Binary

Data portability

Data that can transfer from one system to another easily without having to re-enter data.

System software

Interface between hardware and user; Types include OS (Operating system) and Utility programs

Real time processing

Processed and acted upon immediately; Single input à Single process à Single output

Data validation

Guarantees data is present and the correct type, range or length; Includes presence check, length check, type check, format check, range check

Data integrity

Accuracy and consistency of data

Data redundancy

Unnecessary repetition of data.

Spreadsheet

Software to work out calculations.

Cells

A grid box.

If statements

A function that uses true or false for a specific condition.

VLookup

Short for vertical lookup; Allows to find a specific value within multiple tables.