EXAM 2 CSE 261 DIGITAL LOGIC

Sequential Circuit

A type of circuit where the output is determined by both the current inputs and the past sequence of inputs, making timing and order crucial in the system's operation.

SR Latch

A fundamental bistable storage element with two inputs (Set and Reset) that can hold a single bit of data: it is set to one when the Set input is activated and reset to zero when the Reset input is activated.

D Latch

A level-sensitive device that captures the input value (D) when the control signal (C) is high and retains that value when the control signal is low, allowing for temporary storage in a sequential circuit.

D Flip-Flop

An edge-triggered storage element that captures the value of input D only on the rising edge of a clock signal, ensuring that data changes are synchronized with the clock.

Finite-State Machine (FSM)

A computational model consisting of a finite number of states, transitions between those states based on inputs, and outputs, used for modeling the behavior of sequential systems.

Race Condition

A problematic scenario in sequential circuits where the output varies due to the timing of input changes, causing unpredictability due to multiple signals being processed simultaneously.

Metastability

A state of uncertainty that occurs in digital circuits, particularly in flip-flops, when setup or hold time constraints are violated, leading to erratic output states.

Glitches

Transient unwanted fluctuations in the output signals caused by propagation delays, leading to potential incorrect behavior in circuits.

Boolean Equations

Mathematical expressions that represent the functions of digital circuits in terms of logical variables, reflecting how inputs correspond to outputs.

Timing Diagrams

Visual representations that illustrate the states of signals over time in sequential circuits, aiding in the analysis of time-related behaviors and interactions.

State Machine

A model used in computer science and engineering to design algorithms that operate through a series of defined states and transitions triggered by inputs.

State Diagram

A graphical depiction of a state machine that illustrates all its states and transitions based on various conditions, facilitating understanding of the system's functionality.

Moore Machine

A type of finite-state machine where the outputs are solely dependent on the current state and not influenced directly by the input signals.

Mealy Machine

A variant of finite-state machines where the outputs are determined by both the current state and the current inputs, typically providing faster response to state changes.

Transitions

Processes that describe how a state machine changes from one state to another, usually triggered by specific input conditions.

Input Combination

A particular arrangement of input signals that activates a transition within a state machine, leading to a change in state.

Ambiguous State

A situation in a state machine where a specific input can lead to multiple possible next states, complicating the machine's predictability.

Gray-code Sequence

A binary numeral system in which two consecutive values differ by only one bit, minimizing the risk of errors during state transitions.

Hazard

An unsafe condition in circuit design that can lead to incorrect outputs during transitions due to timing issues.

Output Table

A structured grid that defines the outputs for a state machine based on its current state and input signals, aiding in the design and analysis of sequential circuits.

Tail Lights Sequence

Specific operational modes of vehicle lights represented as distinct states in a state machine, providing clear indications during various vehicle operations.

Circuit Block Diagram

A simplified illustration of an electrical circuit that shows the interconnections and relationships among different circuit components.

Bistable Logic Elements

Feedback circuits capable of maintaining two distinct stable states, commonly used in memory applications.

Clock Characteristics

The attributes of a clock signal, including parameters like frequency, duty cycle, and period, which are essential for the proper function of sequential logic.

Setup Time

The minimum duration prior to a clock edge during which the input signal must remain stable to guarantee reliable data capture.

Hold Time

The minimum duration immediately after a clock edge during which the input signal must stay constant to ensure data integrity in flip-flops.

Characteristic Equations

Equations that model the next state of a flip-flop in relation to its current state and inputs, crucial for designing sequential circuits.

Timing Parameters

Metrics in flip-flops that dictate the performance limits regarding propagation delay, minimum pulse width, setup time, and hold time.

Scan Flip-Flop

A specialized flip-flop designed for testing purposes, capable of operating in both normal mode and test mode, enhancing diagnostic capabilities.

Excitation Equations

Formulas that characterize the necessary input signals for achieving specific transitions in flip-flops, essential for designing sequential systems.

State Transition Table

A comprehensive table that outlines possible states in a system, detailing corresponding actions or outputs in relation to various inputs.

State Table

A tabular representation organizing the states of a state machine, encapsulating current states, inputs, next states, and outputs for clarity.

Transition Equations

Mathematical expressions that detail the conditions required for a state machine to move from one state to another.

State Register

A storage component that maintains the current state of a finite-state machine (FSM), fundamentally influencing the next state based on incoming inputs.

Combinational Logic

Digital logic circuits where the output solely depends on the present input signals, without regard to any previous states or actions.

Truth Table

A comprehensive representation of all possible input combinations for a digital circuit and their corresponding outputs, used to depict circuit behavior.

Clock Cycle

One complete cycle of a clock signal that orchestrates the operations in sequential circuits, determining when state changes occur.

Inputs

Signals that are supplied to a circuit or system, which dictate the behavior and output of state machines and sequential logic.

Outputs

The results produced by a circuit or system in response to specific sets of inputs, forming the end-result of processing.

Input Sequence

The chronological order in which input signals are input into a circuit, influencing the operational behavior and resultant state of the system.