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Master Glossary

All vocabulary terms from the Digital Electronics curriculum, organized alphabetically.

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A

ADC
Analog-to-Digital Converter - converts analog signals to digital
ANSI Symbol
American National Standards Institute standard for logic gate symbols (distinctive shape style)
AOI (And-Or-Invert)
A combinational logic structure consisting of AND gates feeding into an OR gate, with an optional inverter on the output
AOI Configuration
AND-OR-Invert circuit structure; AND gates feed into an OR gate
AOI Logic
AND-OR-Invert logic — a standard form of implementing combinational circuits using AND gates, OR gates, and inverters
ASCII
American Standard Code for Information Interchange—a code that represents text characters as binary numbers.
Active-HIGH
A signal considered "ON" when at logic 1
Active-LOW
A signal considered "ON" when at logic 0
Actuator
A device that converts electrical energy into physical motion or other output
All-NAND
A circuit implementation using only NAND gates
All-NOR
A circuit implementation using only NOR gates
Analog
A continuous signal that can take any value within a range
Analog Design
Design approach dealing with continuously varying signals.
Analog Input
A continuous voltage signal (0-5V) converted to digital value (0-1023)
Analog Sensor
A sensor with a continuously variable output voltage
Analog Signal
A continuously varying signal that can take any value within a range.
Analog-to-Digital Converter (ADC)
A circuit that converts continuous analog signals to discrete digital values
Arduino
An open-source microcontroller platform
Astable Mode
A configuration where the 555 timer continuously oscillates without a stable state.
Asynchronous
Circuit changes occur independent of the clock
Asynchronous (Ripple) Counter
A counter where each flip-flop's output clocks the next flip-flop
Asynchronous Counter
A counter where each flip-flop is clocked by the output of the previous stage (ripple counter)
analogWrite()
Arduino function to output PWM signal

B

BCD
Binary Coded Decimal - represents each decimal digit as a 4-bit binary number
BCD (Binary Coded Decimal)
A 4-bit binary representation where each decimal digit (0-9) is represented by its equivalent 4-bit binary code.
Base / Radix
The number of unique symbols a number system uses (e.g., Base 10 = decimal)
Binary
A number system that uses only two digits (0 and 1). Also called base-2.
Binary Counter
A counter that counts in binary sequence (0000, 0001, 0010...)
Binary Counting Order
Listing inputs in ascending binary sequence (00, 01, 10, 11 for 2 variables) when constructing truth tables
Bit
A single binary digit (0 or 1)
Bit-Serial
One bit per time slot
Bit-Weighting Factor
The positional value of a digit (e.g., 2⁰=1, 2¹=2, 8⁰=1, 16¹=16)
Block Diagram
A diagram showing system components and their connections
Boolean Algebra
The mathematical system governing operations on Boolean variables (variables with only 0 and 1 values)
Boolean Variable
A variable that can only have one of two values: 0 (LOW) or 1 (HIGH)
Borrow-Out
A signal output that pulses HIGH when the counter reaches its minimum value (down counting)
Breadboard
A prototyping board with connected rows and columns for temporarily wiring circuits without soldering
Breadboarding
Building a circuit on a temporary prototyping board
Bubble Pushing
A technique for applying DeMorgan's theorems by moving bubbles and changing gate symbols
Byte
A group of 8 bits

C

CMOS (Complementary Metal-Oxide-Semiconductor)
A family of digital circuits using MOSFETs; lower power consumption and higher component density, but ESD-sensitive
CPU
Central Processing Unit - performs arithmetic and logic operations
Canonical Form
The standard or complete form of a Boolean expression where each term includes all variables
Capacitor
An electronic component that stores electrical energy in an electric field
Carry (C)
The output that represents a "1" to be added to the next higher bit position.
Carry-Out
A signal output that pulses HIGH when the counter reaches its maximum value
Cascading
Connecting counters in series so one triggers the next
Circuit
A complete path through which electricity can flow
Circuit Analysis
The process of determining the truth table and Boolean expression from a given logic circuit diagram
Circuit Design Software (CDS)
Software used to draw schematics and simulate circuit behavior before building physical prototypes (e.g., MultiSim, PLTW S7).
Circuit Implementation
The process of building a logic circuit from a given Boolean expression or truth table
Clock (CLK)
A periodic signal that synchronizes sequential circuits
Clock Enable
A signal that turns the clock on or off to start/stop counting
Clock Signal
A periodic digital signal used to synchronize circuit operations
Closed-Loop Control
System that uses feedback to maintain desired state
Coin Sensor
Detects when coins are inserted
Cold Joint
A defective solder joint caused by insufficient heat; appears dull and grainy
Combinational Logic
A type of digital logic where outputs depend only on current inputs, with no memory of previous states
Common Anode
A 7-segment display where all LED anodes are tied together to VCC; segments light when driven LOW
Common Cathode
A 7-segment display where all LED cathodes are tied together to GND; segments light when driven HIGH
Comparator
A circuit that compares two input voltages and outputs a digital signal
Complement
The inverse of a variable; A' is the complement of A
Complementary Outputs
Q and Q' are always opposite values
Conductor
A material that allows electricity to flow through it (e.g., copper, gold)
Continuous
Having no interruptions or gaps; smooth and unbroken.
Corner Group
A group that uses all four corners of a 4-variable K-map
Counter
A sequential circuit that counts clock pulses
Current (I)
The flow of electrical charge through a conductor; measured in Amps (A); named after Andre-Marie Ampere
Current-Limiting Resistor
A resistor placed in series with each LED segment to limit current and prevent damage to the display.

D

D Flip-Flop
Data flip-flop; captures input D on clock edge, transfers to Q
DIP (Dual In-line Package)
A through-hole IC package with pins extending through the circuit board
DMM
Digital Multimeter — instrument for measuring electrical values
Data Bus
A group of parallel wires that transfer data within a computer
Data Input
The input lines that carry the data to be selected by a multiplexer.
Data Output
The output line where the selected data appears in a multiplexer.
DeMorgan's Theorems
Two fundamental theorems relating AND and OR operations through complementation
Debounce
Handling switch bounce with software delay
Debouncing
Filtering out multiple rapid signals from a mechanical switch
Decade Counter
A counter that counts from 0 to 9 (10 states)
Decimal
The base-10 number system using digits 0-9.
Decoder
A circuit that converts binary information from n inputs to 2^n outputs
Demultiplexer (DEMUX)
A combinational circuit that takes a single input signal and routes it to one of many output lines based on the state of select lines.
Design Brief
A document that defines project goals, requirements, and constraints
Design Mode Software (DMS)
Software used with PLTW hardware to build and test circuits on actual breadboards or PCBs.
Design Process
Systematic approach: define inputs/outputs → truth table → Boolean expression → simplification → circuit
Design from Specification
Creating a circuit starting from a written problem description
Desoldering
The process of removing solder from a joint to disconnect or extract a component
Digital
A signal with discrete values, typically just two states (on/off)
Digital Design
Design approach dealing with discrete signals (typically 0s and 1s).
Digital Sensor
A sensor with two output states: HIGH (1) or LOW (0)
Digital Signal
A signal with discrete values, typically representing only two states (0 and 1).
Discrete
Separate, distinct values; having finite or countable states.
Documentation
Written materials that explain how the system works
Don't Care (X)
A condition that can be treated as either 0 or 1 to maximize group size
Double Negation
The principle that applying NOT twice returns the original value: (A')' = A
Duality
The principle that every Boolean expression remains valid when exchanging 0↔1 and AND↔OR
Duty Cycle
Percentage of time a PWM signal is HIGH
Duty Cycle (D)
The percentage of one period during which the signal is HIGH.

E

Edge-Triggered
A flip-flop that changes state only on a clock transition (rising or falling edge)
Electrocution
Death or serious injury caused by electric shock
Enable Input
An input that must be active for the MUX or DEMUX to function.
Engineering Design Process
A structured approach to solving problems through research, design, testing, and documentation
Engineering notation
Scientific notation where the exponent is a multiple of 3
Even Parity
The condition where the number of 1s in a binary word is even.
Excitation Table
A table that shows what input values are needed to produce a desired state transition
Exponent
The power of 10 in scientific notation (n in a x 10^n)

F

Fall Time (tf)
Time for a signal to transition from 90% to 10% of its final value.
Fan-out
The number of gate inputs a single output can drive without malfunction
Flip-Flop
A bistable circuit that stores one bit of data
Flux
A chemical cleaning agent in solder that removes oxidation and promotes wetting
Flyback Wires
Short wires used to connect separate sections of a breadboard or route signals
Frequency
How often the PWM cycle repeats (Hz)
Frequency (f)
The number of complete cycles per second, measured in Hertz (Hz).
Frequency Division
Dividing an input frequency by an integer
Full Adder
A combinational circuit that adds two 1-bit numbers plus an incoming carry, producing a sum and carry output.

G

GND
Ground reference (0V) connection
Gate Controller
Controls the barrier arm
Gate Propagation
The delay between an input change and the corresponding output change (important for timing, not covered in detail here)
Gray Code
A binary number system where adjacent values differ by only one bit
Ground
A reference point of zero voltage; safety connection to Earth
Grouping
Combining adjacent 1s in a K-map to eliminate variables that change

H

H-Bridge
A circuit that allows control of motor direction by reversing polarity
HIGH (Logic 1)
The higher of two voltage levels used to represent a binary 1.
Half Adder
A combinational circuit that adds two 1-bit numbers, producing a sum and carry output.
Hexadecimal
Base-16 number system; digits 0–9 and A–F
Hold (No Change)
When a flip-flop maintains its current state
Hot Air Rework Station
A tool that blows hot air to melt solder on surface-mount components

I

I/O Ports
Input/Output pins for connecting external devices
IDE
Integrated Development Environment - software for writing/uploading code
IEC Symbol
International Electrotechnical Commission standard for logic gate symbols (rectangular shape with qualifying indicators)
IR Sensor
Infrared sensor that detects objects (vehicles)
Identity
An element that does not change the value when used in an operation (0 for OR, 1 for AND)
Inequality Detector
A circuit that produces a HIGH output when inputs are different.
Insulator
A material that does not conduct electricity (e.g., rubber, glass)
Integrated Circuit (IC)
A complete electronic circuit with many components (transistors, resistors, capacitors) fabricated onto a single semiconductor chip
Integration
Combining multiple subsystems into a complete working system
Intermediate Expression
The Boolean expression at the output of a gate that is not a primary input or final output
Iteration
The process of repeatedly improving a design

J

JK Flip-Flop
Versatile flip-flop with J (set) and K (reset) inputs; J=K=1 toggles
Jitter
Unpredictable, rapid variations in a signal timing or voltage
Jumper wire
A wire used to make connections on a breadboard

K

Karnaugh Map (K-map)
A graphical method for simplifying Boolean algebra expressions
Kirchhoff's Current Law (KCL)
The algebraic sum of currents entering a junction equals the sum leaving; current divides in parallel branches
Kirchhoff's Voltage Law (KVL)
The algebraic sum of all voltages around a closed loop equals zero; voltage drops sum to the applied voltage

L

LED
Light Emitting Diode; a component that emits light when current flows through it
LOW (Logic 0)
The lower of two voltage levels used to represent a binary 0.
LSD
Least Significant Digit — the rightmost digit (lowest place value)
LSI (Large-Scale Integration)
ICs containing 200 to thousands of gates, such as memory chips
Level-Triggered
A flip-flop that can change state while the clock is HIGH (or LOW)
Library
Pre-written code that adds functionality to Arduino
Lifted Pad
A pad that has been separated from the circuit board due to excessive heat
Literal
A variable or its complement; A and A' are both literals
Logic Gate
A basic building block of digital circuits that performs a logical operation on one or more input signals
Logic Level
The voltage range that represents a HIGH (1) or LOW (0) in a digital system.

M

M-of-N Logic
Output is HIGH when at least M of N inputs are HIGH
MSB (Most Significant Bit)
The leftmost bit in a binary number; in signed representation, this is the sign bit.
MSD
Most Significant Digit — the leftmost digit (highest place value)
MSI (Medium-Scale Integration)
ICs containing 20 to 200 gates, such as counters and multiplexers
Majority Function
A logic function where output is HIGH when more than half the inputs are HIGH
Mantissa
The coefficient (a) in scientific notation
Mealy Machine
A state machine where outputs depend on both current state and inputs
Microcontroller
A complete computer on a single chip (CPU + memory + I/O)
Microprocessor
A CPU-only chip that requires external memory and I/O
Minterm
A product term that produces a 1 output; each minterm corresponds to a row where the output is 1
Modulus
The number of unique states in a counter (e.g., modulus-10 counts 0-9)
Modulus (Mod-N)
The number of states in a counter before it resets
Modulus Number (N)
The number of unique states in a modulus counter (e.g., mod-6 has 6 states: 0-5)
Moore Machine
A state machine where outputs depend only on the current state
Multimeter
An instrument that measures voltage, current, and resistance
Multiplexer (MUX)
A combinational circuit that selects one of many input signals and forwards it to a single output line based on the state of select lines.
Multiplexing
Time-sharing a resource between multiple users
map()
Arduino function that converts a value from one range to another
millis()
Arduino function that returns milliseconds since program started

N

NAND Gate
"NOT-AND" — an AND gate followed by a NOT inverter; output is LOW only when ALL inputs are HIGH
NOR Gate
"NOT-OR" — an OR gate followed by a NOT inverter; output is HIGH only when ALL inputs are LOW
Nibble
A group of 4 bits (half a byte).
Noise Immunity
The ability of a system to resist interference that corrupts the signal.
Noise Margin
The amount of additional noise a circuit can tolerate before switching states.
Now Serving Display
A digital display showing the next number in a queue

O

Octal
Base-8 number system; digits 0–7
Odd Parity
The condition where the number of 1s in a binary word is odd.
Ohm
The unit of electrical resistance (symbol: Omega)
Ohm's Law
The fundamental relationship V = I x R, stating that voltage equals current multiplied by resistance
One's Complement
The result of inverting all bits in a binary number.
Open circuit
A break in the circuit; no current flows
Oscillator
A circuit that generates a periodic, oscillating signal.
Overflow
An error condition that occurs when the result of an arithmetic operation exceeds the range that can be represented.

P

POS (Product of Sums)
Expression where sum terms (ORs) are multiplied (ANDed) together: (A + B)·(A + C)
PWM
Pulse Width Modulation - rapidly switching a signal on and off
PWM (Pulse Width Modulation)
Technique to simulate analog output using digital signals
Parallel Circuit
A circuit where current splits through multiple branches that connect across the same voltage
Parallel Data
Data transferred multiple bits simultaneously
Parallel Load
Setting all flip-flops to specific values simultaneously using data inputs
Parallel-in-Serial-out (PISO)
Shift register that accepts parallel input and produces serial output
Parity
A property of binary numbers describing whether the number of 1s is odd or even.
Period (T)
The time for one complete cycle, measured in seconds. T = 1/f
Pin Mode
Configuration for INPUT or OUTPUT
Pinout
A diagram showing the physical layout of pins on an integrated circuit
Place Value
The value of a digit based on its position in a number.
Potentiometer
A variable resistor with three terminals
Power rail
Long strips along the edges that distribute power
Presettable
A counter that can be loaded with a specific starting value
Product of Sums (POS)
A Boolean expression form where sum (OR) terms are multiplied (ANDed) together; derived from truth table rows where output = 0
Programmable Logic Device (PLD)
A device with configurable logic gates
Propagation Delay
The time delay between an input change and the corresponding output change
Protoboard
Another name for breadboard
Prototype
A working model of the final product
Prototyping
Building a test version of a circuit before final production
Pull-up Resistor
Keeps input HIGH when not connected

Q

Quantization
The process of converting continuous analog values into discrete digital steps.

R

RAM
Random Access Memory - volatile storage for data
ROM/Flash
Non-volatile memory for program storage
Register
A group of flip-flops that store multiple bits of data
Reset
When Q is forced to 0 (LOW)
Resistance (R)
The opposition to the flow of current; measured in Ohms (Omega); named after Georg Ohm
Resistor
A component that opposes the flow of current; measured in ohms
Ripple Carry Adder
A multi-bit adder created by cascading full adder circuits, where carries propagate through each stage.
Rise Time (tr)
Time for a signal to transition from 10% to 90% of its final value.

S

SI prefix
A prefix (kilo, mega, milli, etc.) that multiplies a base unit
SOIC (Small Outline Integrated Circuit)
A surface-mount IC package with pins extending outward from the sides
SOP (Sum of Products)
Expression where product terms (ANDs) are summed (ORed) together: A·B + A·C
SSI (Small-Scale Integration)
ICs containing 1 to 20 gates or flip-flops
Safety Interlock
A mechanism that prevents equipment operation when unsafe conditions exist
Sampling
Taking measurements of an analog signal at regular intervals.
Schematic
A symbolic representation of a circuit showing how components are connected.
Scientific notation
A number expressed as a x 10^n where 1 <= a < 10
Segment
One of the seven illuminated bars (a-g) plus the decimal point (dp) that make up a seven-segment display.
Select Lines
Input lines that determine which data input is selected (MUX) or which output is enabled (DEMUX).
Sensor
A device that converts a physical quantity into an electrical signal
Sensor Fusion
Combining data from multiple sensors
Sequential Logic
Logic circuits where output depends on current inputs AND previous state (has memory)
Serial Data
Data transferred one bit at a time sequentially
Serial Monitor
A window to send/receive text to Arduino
Serial-in-Parallel-out (SIPO)
Shift register that accepts serial input and produces parallel output
Series Circuit
A circuit where current flows through components one after another on the same path
Servo Motor
A motor that rotates to a specific angle
Set
When Q is forced to 1 (HIGH)
Seven-Segment Decoder
An IC that converts binary/BCD to 7-segment display signals
Seven-Segment Display
A display device with 7 LED segments (a-g) that can form digits 0-9
Shift Register
A register where data moves (shifts) one position per clock pulse
Short circuit
An unintended path with little or no resistance
Sign-Magnitude
A representation where the MSB indicates sign (0 = positive, 1 = negative) and remaining bits represent magnitude.
Signal Path
The route that an electrical signal follows from an input through one or more gates to the output
Signed Number
A number that can represent both positive and negative values in a binary system.
Simplification
The process of reducing a Boolean expression to an equivalent form with fewer terms or literals
Simulation
Using software to model how a circuit will behave before physical construction.
Sketch
An Arduino program file
Solder
A metal alloy (typically tin and lead or tin and silver) that melts at low temperatures and creates an electrically conductive bond
Solder Bridge
An unintended connection of solder between two adjacent conductors
Solder Sucker
A spring-loaded tool that creates suction to vacuum up molten solder (also called desoldering pump)
Solder Wick
A braided copper wire that absorbs liquid solder through capillary action (also called desoldering braid)
Soldering
Joining components with melted metal alloy
Soldering Iron
A hand tool with a heated metal tip used to melt solder and join components
State
A specific condition or mode of the system
State Diagram
A graphical representation showing states and transitions
State Encoding
Assigning binary codes to each state
State Machine
A circuit with a finite number of states that transitions between states based on inputs
State Table
A table showing current state, inputs, next state, and outputs
State Transition
Moving from one state to another based on inputs
Subexpression
A portion of a larger Boolean expression, typically representing the output of an intermediate gate
Successive Division
Method for converting decimal → another base by repeated division
Sum (S)
The result of adding two binary digits; represents the units place of the addition.
Sum of Products (SOP)
A Boolean expression form where product (AND) terms are summed (ORed) together; derived from truth table rows where output = 1
Surface mount
Components mounted directly on the surface of a PCB
Surface-Mount (SMD)
Components mounted directly on the surface of the circuit board without holes
Synchronous
All flip-flops share the same clock; change simultaneously
Synchronous Counter
A counter where all flip-flops share a common clock
switch/case
A programming structure that selects code based on state value

T

TTL (Transistor-Transistor Logic)
A family of digital circuits using bipolar junction transistors; faster but uses more power and is not ESD-sensitive
Terminal strip
The main area of a breadboard where components are inserted
Theorem
A proven statement that can be used to simplify Boolean expressions
Thermal Shock
Rapid temperature change that can crack or damage components and circuit boards
Threshold
A predetermined voltage level that triggers a change in circuit behavior
Through-Hole
Component leads that pass through holes in the circuit board and are soldered on the opposite side
Timing Diagram
Graph showing signal levels (HIGH/LOW) over time
Tinning
Applying a small amount of solder to the tip of an iron to improve heat transfer
Toggle
When a flip-flop output switches between HIGH and LOW
Tolerance
How much a component's actual value can vary from its marked value
Tollbooth
A barrier system that collects fees from vehicles
Total Resistance
The combined resistance of all components in a circuit
Transistor
A semiconductor device that amplifies or switches electronic signals
Truth Table
A systematic listing showing all possible combinations of input values and their corresponding output values
Truth Table to Circuit
The complete design process from requirements to working hardware
Two's Complement
The most common method for representing signed numbers in binary; positive numbers are unchanged, negative numbers are found by inverting bits and adding 1.

U

Universal Gate
A gate type that can be used to implement any Boolean function (NAND and NOR are universal)
Universal Gates
NAND and NOR gates that can be used to implement any Boolean function
Upload
Transferring code from computer to Arduino

V

VCC
The positive power supply voltage (+5V for TTL logic)
VIH
Minimum input voltage guaranteed to be recognized as HIGH.
VIL
Maximum input voltage guaranteed to be recognized as LOW.
VLSI (Very-Large-Scale Integration)
ICs containing thousands to millions of gates, such as microprocessors
VOH
Minimum output voltage guaranteed to be recognized as HIGH by an input.
VOL
Maximum output voltage guaranteed to be recognized as LOW by an input.
Vehicle Sensor
Detects when a vehicle is present
Voltage (V)
The electrical force or pressure that pushes charge through a circuit; measured in Volts (V); named after Alessandro Volta
Voltage Divider
A circuit that produces an output voltage proportional to input voltage

W

Weighted Multiplication
Method for converting any base → decimal by multiplying by place values
Weighted Sum
A method of conversion where each digit is multiplied by its place value.
Wetting
The process of solder flowing and bonding to clean metal surfaces
Wrapping Group
A group that wraps around the edge of the K-map (top to bottom, left to right)

X

XNOR (Exclusive NOR)
A logic gate that produces a HIGH output only when the inputs are the same (both HIGH or both LOW).
XOR (Exclusive OR)
A logic gate that produces a HIGH output only when the inputs are different (one HIGH, one LOW).

Z

Zero Detection
Logic that detects when the counter reaches zero