Unit 1 comp sci

hexadecimal number system

hexadecimal number system

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

ASCII code

a character set for all the characters on a standard keyboard and control codes

Character set

A list of characters that have been defined by computer hardware and software. The character set is
necessary so that the computer can understand human characters

Sampling resolution

the number of bits used to represent sound amplitude in digital sound recording (also known as bit depth)

Bit depth

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

Colour depth

the number of bits used to represent the colours of a pixel

Sampling rate

the number of sound samples taken per second in digital sound recording

Pixel density

number of pixels per square inch

Compression

reduction of the size of a file by removing repeated or redundant pieces of data; this can be lossy or lossless

Bandwidth

THe maximum rate of transfer of data across a network, measured in kilobits per second (kbps) or megabits per second (Mbps)

Audio compression

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

MP3

a lossy file compression method used for music files

Run Length Encoding (RLE)

a lossless file compression technique used to reduce text and photo files in particular.

Bit

The basic computing element that is either 0 or 1

Byte

The smallest operable units of storage in a computer, consists of 8 binary digits

Error code

an error message generated by the computer

MAC address

A Media Access Control address is a hardware address that uniquely identifies each device on a network.

IP Address

Internet Protocol identified either as IPv4 or IPv6; it gives a unique address to each device connected to a network identifying their location

HTML

HyperText Mark-up Language is used in the design of web pages and to write, for example, http(s) protocols; in the context of this chapter, colours used in web pages are assigned a hexadecimal code based on red, green and blue colours

Unicode

a character set which represents all the languages of the world (the first 128 characters are the same as ASCII code)

Bitmap image

an image made up of pixels

Pixel

derived from the term 'picture element', this is the smallest element used to make up an image on a display

Image Resolution

image resolution - the number of pixels in the X-Y direction of an image, for example, 4096 × 3192 pixels

Lossy

A file compression method in which parts of the original file cannot be recovered during the decompression process for example, JPEG, mp3

Lossless

a file compression method that allows the original file to be fully restored during the decompression process, for example, run length encoding (RLE)

MP4

a lossy file compression method used for multimedia files

JPEG

from Joint Photographic Expert Group; a form of lossy file compression used with image files which relies on the inability of the human eye to distinguish certain colour changes and hues