Computer Science IGCSE Unit 1

This flashcard set is directly taken from Hodder Education's Cambridge IGCSE and O Levels Computer Science textbook (2nd Edition). This is carefully catered towards the syllabus and understanding of the terms will most likely translate to an understanding of the syllabus to better prepare you for the exams!

Bit

Bit

Comes from binary digit-- basic computing element that are either 1s or 0s

Binary number system

a number system based on 2 and powers of 2, can only use the values 0 and 1

Hexadecimal number system

A number system based on the value 16 which uses denery digits 0 to 9 and letters A to F

Error code

Unique identifier of an error message and error generated by the computer

MAC address

Media access control, given in hexadecimal, uniquely identifies a device on the internet. Taking the form of NN-NN-NN-DD-DD-Dd where the Ns are the code of the manufacturer and the Ds are the unique identifer of the device hard wired on the NIC card

IP address

Internet protocol address. IPv4 (four groups of hexadecimals separted by.) or IPv6 (eight groups of hexadecimals separated by:). It gives a unique address to each device connected to any network identifying their location. (Most use dynamic iP addresses which will change when connecting to different networks.)

HTML

Hyper text mark up langugage. Used in design of web pages and protocols writing. Colours used in html web pages are assigned a unique hex code.

Overflow error

The result of carrying out a claculation that produces a value too large for the computer's allocated word size (8 bits of 16 bits etc)

Logical Shifts

The act of shifting binary digits to the left or right in a reigster, any bits shifted out are replaced with 0s.

Two's complement

A method of rep of negative numbers in binary, when applied to an 8bit register, the most significant bit is given a negative value.

ASCII code

American Standard Code for Info Interchange is a set character set for all the characters on a standard keyboard written in binary digits or hex.

Character set

A list of characters that have been defined by computer hardware and sfotware, necessary so computer can understand human characters.

Unicode

Character set representing all the languages in the world (the first 128 are the same as ASCII)

Sampling resolution

The number of bits used to represent sound amplitude in digital sound recording (bit depth)

Bit Depth

the number of bits used to represent the smallest unit in a sound file.

Colour depth

The number of pixels used to represent the colours of a pixel.

Sampling rate

The number of sound samples taken per second in a digital sound recording (measured in Hertz)

Bitmap images

An image made up of pixels

Pixels

Derived from the word picture element, this is the smallest element used to make up an image on a display

Image resoulution

The number of pixels in the X or Y direction of an image

Pixelated image

Result of zooming in one a bitmap image, on zooming in the pixel density can be diminished to such a degree that the individual pixels can be seen.

Pixel density

Number of pixels per square inch

Compression

Reduction of the size of a file by removing repeated or redundant pieces of data, can be lossy or loseless

Bandwidth

The maximum rate of file transfer of data across a network, measured in kilobits per second or megabits per second

Lossy file compression

A file compression method in which parts of the original file cannot be recorded during the decompression process (e.g JPEG and mp3/4)

Loseless file compression

A file compression method that allows the original file to fully restored during the decompression process. Ex. RLE

Audio compression

Method used to reduce the size of a sound file using perceptual music shaping

MP3 and MP4

Lossy file compression method for sound and multimedia files.

JPEG

Joint photography expert group made this: it is a form of lossy file compression used with image files which relies on the ability of the human eye to distinguish certain colour changes and hues.