Chapter 1: Data Representation - Key Vocabulary

A set of vocabulary flashcards covering number systems, text/sound/images representation, storage, and compression concepts from the lecture notes.

Binary number system

Base-2 numeral system used by computers; uses digits 0 and 1 to represent data as ON/OFF states.

Denary (decimal) system

Base-10 numeral system using digits 0–9; standard human counting system.

Hexadecimal

Base-16 numeral system using digits 0–9 and letters A–F; 4 bits per hex digit.

8-bit register

A storage unit that holds 8 bits; maximum unsigned value is 255; can overflow if a larger value is stored.

Overflow

When a binary sum cannot be represented within the fixed number of bits available (e.g., >255 in 8-bit unsigned).

Binary addition

Addition of binary numbers using rules 0+0=0, 0+1=1, 1+0=1, 1+1=0 with a carry of 1.

Logical shift

Shifting a binary number left or right; left shift multiplies by 2^n, right shift divides by 2^n; new bits filled with zeros.

Two's complement

A method to encode signed integers where the leftmost bit denotes sign; for 8-bit, range is -128 to +127.

Sign bit

The most significant bit in a two's-complement representation that indicates negative (1) or positive (0).

ASCII

7-bit character encoding (0–127) representing letters, digits, and control codes; Extended ASCII uses 8 bits (0–255).

Extended ASCII

8-bit extension of ASCII adding additional characters beyond the original 0–127 range.

Unicode

A universal character encoding system capable of representing many languages; uses 2–4 bytes per character in common encodings.

ASCII vs. Unicode

ASCII is a 7-bit/8-bit code for English characters; Unicode provides broader language support with multi-byte encodings.

Sampling rate

Number of samples per second used to convert analog sound to digital; higher rates yield better fidelity but larger files.

Sampling resolution (bit depth)

Number of bits used per audio sample; higher depth increases dynamic range and quality but increases file size.

Colour depth

Bits per pixel used to represent a color in an image; higher depth allows more colors (e.g., 8-bit = 256 colors, 24-bit true color).

Bitmap image

Digital image stored as a grid of pixels; each pixel encoded with a certain color depth.

Pixel

The basic picture element in a bitmap image; the smallest controllable element of a picture represented as a binary value.

Image resolution

Number of pixels in an image, typically width × height; higher resolution increases file size and detail.

Kibibyte (KiB)

IEC binary memory unit equal to 2^10 bytes (1024 bytes); part of the KiB/MiB/GiB series.

Lossy compression

Data compression that discards some information to reduce size (e.g., MP3, MP4, JPEG); original cannot be perfectly reconstructed.

Lossless compression

Compression that preserves all original data so the exact original file can be reconstructed (e.g., some forms of RLE).

Run-length Encoding (RLE)

Lossless compression that encodes consecutive repeated data as a count and a value; effective for long runs.

MP3

A lossy audio compression format (MPEG-1/2 Layer III) that greatly reduces file size by discarding inaudible data.

MP4

A lossy multimedia container format that can store audio, video, and images; uses lossy compression for size efficiency.

JPEG

A lossy image compression standard that reduces file size by discarding some image data, often using 8×8 pixel blocks.

MAC address

48-bit hardware address for a network interface card; shown as six groups of two hexadecimal digits; uniquely identifies a device.

IPv4 address

32-bit IP address written in dotted decimal form (four octets).

IPv6 address

128-bit IP address written in hexadecimal groups separated by colons.

HTML color code

Six hexadecimal digits following a # that specify the red, green, and blue components (RRGGBB).