NCEA Level 2 Digital Technologies flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

IPO model

A way of describing any program as three parts: input (data received), process (calculations, selection, iteration), and output (results displayed or stored).

Selection control structure

A control structure that chooses which statements run based on a condition, implemented with if, elif, else, or a switch statement.

While loop

An iteration structure that tests its condition before each repetition, so the body runs zero or more times and stops when the condition becomes false.

Boolean AND versus OR

AND returns true only when both operands are true; OR returns true when at least one operand is true. NOT inverts a single value.

Function parameter and return

A parameter is a value passed into a function; a return value is the result sent back to the caller. Functions hide internal detail and can be reused.

Trace table

A debugging and testing tool that records the value of each variable after every line or iteration, letting a programmer check logic by hand.

Boundary testing

Testing at the edges of valid input, such as zero, one, the maximum, and maximum plus one, because errors most often occur at these limits.

Binary search

A fast search that repeatedly halves a sorted list, comparing the middle item to the target, so it needs far fewer comparisons than a linear search.

Ohm's law

The relationship V = I × R between voltage in volts, current in amps, and resistance in ohms, used to calculate any one value from the other two.

Series circuit

A circuit with a single path: current is identical through every component, total resistance is the sum of resistances, and voltage divides across components.

Parallel circuit

A circuit with multiple branches: voltage is the same across each branch, current splits between branches, and total resistance is less than the smallest branch.

AND gate

A digital logic gate whose output is 1 only when every input is 1; any 0 input makes the output 0.

Analogue to digital converter

A component that samples a continuous analogue voltage and converts it to a discrete number, such as a 10-bit reading from 0 to 1023.

Pulse width modulation

Rapidly switching a digital output on and off to vary the proportion of on-time, approximating analogue control of LED brightness or motor speed.

Pull-down resistor

A resistor connecting an input pin to ground so the pin reads a defined low voltage when a switch is open, preventing random floating readings.

Microcontroller

A single chip containing a processor, memory, and input/output pins that runs a stored program to read sensors and control actuators.

Hexadecimal

A base-16 number system using digits 0-9 and letters A-F, where each hex digit represents exactly four binary bits, making binary easier to read.

Byte and bit

A bit is a single binary digit, 0 or 1; a byte is a group of eight bits, the standard unit for measuring data storage.

Lossy compression

A compression method that permanently discards some data to reduce file size, used in formats such as JPEG and MP3 where slight quality loss is acceptable.

Lossless compression

A compression method that reduces file size while allowing the original data to be reconstructed exactly, used in formats such as PNG and ZIP.

Primary key

A field or combination of fields that uniquely identifies each record in a database table and cannot contain duplicate or null values.

Foreign key

A field in one table that references the primary key of another table, creating a link between the tables and enforcing referential integrity.

Data validation

A rule that checks whether input meets set criteria such as type, range, length, or presence before it is accepted into a system.

Unicode

A character encoding standard covering the scripts of the world; UTF-8 encodes each character in one to four bytes.

Raster image

An image made of a grid of pixels, each with a colour value; enlarging it beyond its resolution reveals visible pixelation.

Vector graphic

An image described by mathematical paths, shapes, and fills rather than pixels, so it can be scaled to any size without losing quality.

Colour depth

The number of bits used per pixel; 8-bit gives 256 colours, while 24-bit true colour gives about 16.7 million colours across red, green, and blue channels.

Image file size formula

Uncompressed size in bytes equals width times height times colour depth in bits, divided by eight; for example 1000 by 1000 pixels at 24-bit is about 3 MB.

Sample rate and bit depth

Sample rate is how many audio samples are taken per second, such as 44.1 kHz for CD; bit depth is the bits per sample, such as 16.

Frame rate

The number of video frames displayed per second; higher frame rates give smoother motion but increase file size proportionally.

CARP design principles

Contrast, alignment, repetition, and proximity: four layout principles that improve readability and visual coherence in digital media products.

Creative Commons licence

A public licence letting creators share work under stated conditions, such as attribution or non-commercial use, without individual permission for each use.