Exam 2 Flashcards
The output depends only on the input
Combinational circuits
Methods to describe a combinational circuit
Truth table
Boolean algebraic expression
Logic diagram
Lists the output for every combination of the input
Truth table
Computers, as we know them today, are implementations of:
Boole’s Laws of Thought.
is a mathematical system for the manipulation of variables that can have one of two values .
Boolean algebra
A Boolean function has:
At least one Boolean variable,
At least one Boolean operator,
and At least one input from the set{0,1}.
What is xy and x+y using DeMorgans Law?
Negate and switch ors and ands
x’ + y’ and x’y’
An interconnection of logic gates
Closely resembles the hardware
Logic diagrams
is a matrix consisting of rows and columns that represent the output values of a Boolean function .
A Kmap
is a product term that contains all of the function’s variables exactly once, either complemented or not complemented .
A minterm
If a circuit is designed so that a particular set of inputs can never happen , we call this set of inputs a:
don’t care condition
In a sigma(E) expression
represents the 1 outputs
In a PI notation
Represents the 0s
Enable line
Turns the device on or off. If 0 the output is 0. If 1 the output is 1
Invert
Turns the device on or off. If 0 the output is 1. If 1 the output is 0
What is a multiplexer?
A multiplexer selects one of several data inputs to be routed to a single data output
What is a binary decoder?
A decoder takes a binary number as input and sets one of the data output lines to 1 and the rest to
What is a demultiplexer?
a A demultiplexer routes a single input value to one of several output lines
What is a half adder?
The half adder adds the right-most two bits of a binary number
Inputs : The two bits
Outputs : The sum bit and the carry bit
What is a full adder?
The full adder adds one column of a binary number
adds two n-bit binary numbers
The ripple-carry adder
You can only get an overflow in one of two cases:
A and B are both positive, and the result is negative
A and B are both negative, and the result is positive
are perfect for situations when we require the immediate application of a Boolean function to a set of inputs.
Combinational logic circuits
a circuit that can change its value with consideration to its current state as well as its inputs .
Sequential logic circuits
Circuits that change state on the rising edge , or falling edge of the clock pulse are called
edge triggered
change state when the clock voltage reaches its highest or lowest level.
Level- triggered circuits
To retain their state values, sequential circuits rely on:
in digital circuits occurs when an output is looped back to the input.
feedback
The difference between a latch and a flip flop is that a latch is:
asynchronous , and the outputs can change as soon as the inputs do
is edge triggered and only changes state when a control signal goes from high to low or low to high
A flip-flop
is a group of wires connecting two subsystems
A bus
