Chapter 1: Data representation Flashcards
Define a bit
The basic computing element that is either 0 or 1
Define the binary number system
A number system based on 2 and can only use values 0 and 1
Define an error code
It is an error message generated by the computer
Define a MAC address
It is an address (given in hexadecimal) that uniquely identifies a device on the internet in the form of NN-NN-NN-DD-DD-DD
(NN-NN-NN is the manufacturer code)
(DD-DD-DD is the device code)
Define an IP address
It is an address that uniquely identifies each device connected to a network identifying their location.
Define HTML
It is used to design and write webpages
Define an overflow error
The result of doing a calculation that produces a value that is too big for the computers allocated word size
Define logical shift
An operation that shifts bits to the left or right in a register.
(Any bits shifted out of the register are replaced with zeroes)
Define the two’s complement
A method of representing of negative numbers in binary
(When applied to an 8-bit system, the left most bit is given the value -128
What is an ASCII code
A character set for all the characters on a standard keyboard and control codes.
Define a character set
a list of characters that have been defined by computer hardware and software.
Define an Unicode
a character set which represents all the languages of the world
Define a sampling resolution
the number of bits used to represent sound amplitude in digital sound recording
Define what is bit depth
the number of bits used to represent the smallest unit in a sound file
Define what is color depth
the number of bits used to represent the colours of a pixel
Define sampling rate
the number of sound samples taken per second in digital sound recording
Define bitmap image
an image made up of pixels
Define pixel
the smallest element used to make up an image on a display
Define image resolution
the number of pixels in the X–Y direction of an image,
Define pixelated image
this is the result of zooming into a bitmap image; on zooming out the pixel density can be diminished to such a degree that the actual pixels themselves can be seen
Define pixel density
number of pixels per square inch
Define compression
reduction of the size of a file by removing repeated or redundant pieces of data;
Define bandwidth
the maximum rate of transfer of data across a network, measured in kilobits per second (kbps) or megabits per second (Mbps)
Define lossy file compression
a file compression method in which parts of the original file cannot be recovered during the decompression process
Define lossless file compression
A file compression method that allows the original file to be fully restored during the decompression process, for example, run length encoding (RLE)
Define audio compression
a method used to reduce the size of a sound file using perceptual music shaping
Define MP3
a lossy file compression method used for music files
Define MP4
a lossy file compression method used for multimedia files
Define JPEG
; 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
Define RLE
a lossless file compression technique used to reduce the size of text and photo files in particular
How do you calculate The file size of an image
image resolution (in pixels) × colour depth (in bits)
How do you calculate The size of a mono sound file
sample rate (in Hz) × sample resolution (in bits) × length of sample (in seconds)
Why is file compression necessary
» to save storage space on devices such as the hard disk drive/solid state drive
» to reduce the time taken to stream a music or video file
» to reduce the time taken to upload, download or transfer a file across a network
» the download/upload process uses up network bandwidth
» reduced file size also reduces costs.
Define a data packet
a small part of a message/data that is transmitted over a network
Define a data packet
a small part of a message/data that is transmitted over a network
