Fundamentals of Digital Logic Flashcards
What is Voltage?
● Measure of potential Force
● It is measured in Volts
What is Current?
● Measure of electron flow across a wire
● It is measured in Amps
How are 0s and 1s represented in a computer?
It is based on digital currents
● Ground - 0 volts – represent a “0”
● Power – 5 volts – represent a “1”
What is a transistor?
● Building block of digital circuits
● Acts like a switch
What are a transistors connections, and how do they work?
● A transistor has three connections:
● Emitter
● Base
● Collector
The current between “Base” and “Emitter”
controls the current between “Collector” and “Emitter”.
What do the and, or, and not gates look like? (Visualize in head)
|) is AND, )) is Or, |*trangle is NOT
A and B as boolean expression
AB
A or B as boolean expression
A+B
not A as boolean expression
A’
Sum of Products
Way to represent boolean expression.
To create from truth table: Take 1 outputs, if input is x = 1, use x. If input Is x = 0 use x’. IF MATCHING USE NORMAL VAR
z = x’y + xy’
Product of sums
Way to represent boolean expression
To create from truth table: Take 0 outputs, if input is x = 0, use x. If input Is x = 1 use x’. IF MATCHING USE NORMAL VAR
z = (x+y)(x’+y’)
De Morgan’s law
Useful in boolean math. Negates expression
(A+B)’ = A’B’
(AB)’ = A’ + B’
Karnaugh Map
Way of expression truth table.
How to generate Karnaugh Map?
- Draw table
- Find groups of 2, 4, 8 1s that are adjacent
- Build expression from groups
Overlapping more is good because it yields a smaller final expression
How can you convert a boolean expression to only use NAND gates?
To convert a sum of products to only NAND gates negate the function twice and reduce
How much memory can a RS flip flop store?
1 bit
What is different when you make a flip flop from only NANDs?
Inverted inputs and outputs, R’S’ “maps” to Q’ Q
What does a D Latch do?
Adds Enable input to keep or set value from input D
What is a Binary Counter?
● Counts pulses (transitions from 0 to 1)
● Output is a binary number
● Contains a terminal to reset ouput to 0
What is a clock?
It is an electronic circuit that produces a
sequences of 0 1 0 1 0 1
What is the clock used for?
It is used to synchronize operations across gates in active circuits.
How is clock speed measured?
The frequency is measured in hertz
What is a demultiplexor?
It is a circuit used to select one output. (research a little more)
On a low level, how can a circuit use components to execute a series of steps.
Clock provides frequencies, a counter counts those frequencies and produces and output, the demultiplexor takes that output and triggers different steps.
