NCEA L1 Digital Tech flashcards

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

Sequence control structure

Statements execute one after another in the order written. It is the default flow of any program and forms the baseline before selection or iteration alters execution order.

Selection control structure

Uses conditions (if, elif, else, switch) to choose between alternative paths. The boolean result of the condition decides which block of code runs next.

Iteration control structure

Repeats a block of code. Definite iteration uses a for-loop with a known count; indefinite iteration uses a while-loop driven by a condition that must eventually become false.

Variable and data type

A variable is a named reference to stored data. Its data type (integer, float, string, boolean) determines which operations are valid and how memory is interpreted.

Modulo operator

The % operator returns the remainder after integer division. For example 17 % 5 equals 2. It is commonly used to test divisibility or wrap values within a range.

Function parameter and return

Parameters pass input values into a function. A return statement sends a value back to the caller. Variables declared inside the function are local to its scope only.

Boolean operators AND OR NOT

AND is true only when both operands are true. OR is true when at least one is true. NOT inverts a value. Precedence order is NOT, then AND, then OR.

Unit versus integration testing

Unit testing checks one function or module in isolation. Integration testing checks that multiple modules work correctly together. Both differ from acceptance testing, which confirms user requirements are met.

Ohm's Law

Voltage equals current multiplied by resistance (V = I × R). Rearranged, current equals voltage divided by resistance, and resistance equals voltage divided by current.

Electrical power formula

Power in watts equals voltage multiplied by current (P = V × I). Equivalent forms are P = I²R and P = V²/R, useful when only resistance and one other quantity are known.

Series circuit rules

Components connect in one path. Current is identical through every component, total resistance is the sum of individual resistances, and supply voltage divides across components.

Parallel circuit rules

Components connect across the same two nodes. Voltage is identical across every branch, total resistance is found from the reciprocal sum, and supply current divides between branches.

Digital versus analog signal

A digital signal has two discrete levels, HIGH and LOW, represented as 1 and 0. An analog signal varies continuously across a range of values over time.

Embedded system definition

A computer system built into a larger device to perform a dedicated function. It combines a microcontroller, firmware, and input or output devices rather than serving as a general-purpose computer.

Sensor and actuator roles

A sensor is an input device converting a physical quantity such as light or temperature into an electrical signal. An actuator is an output device converting an electrical signal into physical action.

Pulse-width modulation duty cycle

PWM rapidly switches a digital output on and off to control average power. Duty cycle equals on-time divided by period, expressed as a percentage of full power.

Microcontroller versus microprocessor

A microcontroller integrates CPU, memory, and input/output pins on a single chip. A microprocessor contains the CPU alone and requires external memory and peripheral chips to operate.

Data versus information

Data consists of raw, unprocessed symbols or values. Information is data that has been processed and organised into meaningful context for a specific purpose or decision.

Binary to decimal conversion

Sum the place values of each 1 bit, where places double from right to left (1, 2, 4, 8, 16). For example 1011 in binary equals 8 + 2 + 1 = 11.

Bits bytes and storage units

One byte equals eight bits. One kilobyte equals 1024 bytes, one megabyte equals 1024 kilobytes, and one gigabyte equals 1024 megabytes in binary-based storage measurement.

Hexadecimal notation

A base-16 number system using digits 0-9 and letters A-F. Each hex digit represents exactly four bits, so two hex digits represent one byte compactly.

Character encoding ASCII and Unicode

Encoding maps characters to numeric codes. ASCII uses seven or eight bits for 128 or 256 characters. Unicode uses far more code points to represent worldwide writing systems.

Record field and database

A database is an organised collection of related data. A record is one complete set of fields describing a single entity. A field is one attribute within that record.

Primary and foreign keys

A primary key uniquely identifies each record in a table. A foreign key is a field holding a primary key value from another table, creating a relationship between the tables.

Validation versus verification

Validation checks data is reasonable and within accepted rules, such as range or type checks. Verification checks data was entered accurately, for example by double entry.

Lossless versus lossy compression

Lossless compression reduces file size while preserving all original data exactly, as in PNG or ZIP. Lossy compression permanently discards data considered less perceptible, as in JPEG or MP3.

Raster image file size

Uncompressed size in bytes approximates width times height times colour depth in bits, divided by eight. Doubling resolution in both directions quadruples the file size.

Raster versus vector graphics

Raster graphics store a grid of pixels and lose quality when enlarged. Vector graphics store mathematical paths and scale to any size without pixelation or quality loss.

RGB versus CMYK colour

RGB is an additive model mixing red, green, and blue light for screens. CMYK is a subtractive model mixing cyan, magenta, yellow, and black ink for print output.

Audio sample rate and bit depth

Sample rate is the number of audio samples captured per second, such as 44.1 kHz. Bit depth is the bits per sample, such as 16-bit, determining dynamic range and accuracy.

Frame rate in digital video

Frame rate is the number of still images displayed per second, measured in fps. Higher rates produce smoother motion but increase file size and processing demands.

Aspect ratio

The proportional relationship between an image's width and height, expressed as width:height, such as 16:9 or 4:3. Changing it without cropping causes stretching or distortion.