Computer Science Data Representation and Transmission Vocabulary

This set of vocabulary flashcards covers essential terms related to number systems, data representation of text, sound and images, and data transmission methods including error detection and encryption.

Bit

The most fundamental unit of computing data, short for 'binary digit', which takes the value of either $0$ or $1$.

Byte

A standard unit of computer memory consisting of exactly $8$ bits.

Nibble

A unit of data consisting of $4$ bits, or half of a standard byte.

Binary number system

A base-$2$ numerical system that uses only two digits, $0$ and $1$, to represent all values.

Hexadecimal number system

A base-$16$ numerical system that utilize sixteen distinct symbols: denary digits $0$ to $9$ and letters $A$ to $F$.

Overflow error

A computer error that occurs when a calculation produces a numerical value that exceeds the storage capacity of the allocated bit register.

Logical binary shift

An operation where the bits in a sequence are moved left or right; shifting left usually multiplies the value by $2$, while shifting right divides it by $2$.

Two’s complement

A method for representing both positive and negative integers in binary, where the most significant bit holds a negative weight, such as $-128$ in an $8$-bit system.

ASCII

Standing for American Standard Code for Information Interchange, this system uses $7$-bit or $8$-bit codes to represent characters on a keyboard.

Unicode

A universal character encoding standard designed to represent all writing systems and languages in the world, often using $16$-bit or $32$-bit codes.

Pixel

Abbreviated from 'picture element', this is the smallest individual component that makes up a digital bitmap image.

Colour depth

The specific number of bits used to represent the variety of colours available for a single pixel in an image.

Resolution

In images, this refers to the total number of pixels that constitute the image; in sound, it refers to the number of bits used per sample.

Sampling rate

The frequency at which sound amplitude measurements are taken per second, measured in hertz ($Hz$).

Lossy compression

A data reduction method that removes unnecessary information, permanently altering the file so the original cannot be perfectly reconstructed.

Lossless compression

A compression technique that reduces file size without losing any original data, allowing the file to be fully restored to its original state.

Packet

A discrete unit of data, typically around $64KiB$, used for transmitting information over a network.

Packet switching

A data transmission method where a message is divided into packets that are routed independently across a network to their destination.

Simplex transmission

A mode of data transmission where information can only travel in one fixed direction.

Half-duplex transmission

A mode of data transmission where information can travel in both directions, but not simultaneously.

Full-duplex transmission

A mode of data transmission where information travels in both directions at exactly the same time.

Serial data transmission

The process of sending data bits one at a time sequentially over a single communication channel or wire.

Parallel data transmission

The process of sending multiple data bits simultaneously over several distinct channels or wires.

USB

Universal Serial Bus; a standard asynchronous serial data transmission method used for connecting peripheral devices to a computer.

Parity check

An error detection technique that uses an additional bit to ensure the total number of $1$-bits in a byte is either even or odd.

Checksum

An error-checking value calculated from a block of data using an algorithm and sent alongside the data to verify transmission integrity.

Check digit

A final digit appended to a code, such as an $ISBN$ or barcode, used to detect manual data entry errors.

ARQ

Automatic Repeat Request; an error control method that uses acknowledgments and timeouts to request the re-sending of data.

Symmetric encryption

A form of encryption where the sender and receiver use the same secret key to both encrypt and decrypt the information.

Asymmetric encryption

An encryption method involving a pair of mathematically linked keys: a public key for encryption and a private key for decryption.