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.
What is an example of Small Scale Integration (SSI)?
Basic boolean gates.
What is an example of Medium Scale Integration (MSI)?
Intermediate logic such as demultiplexers and counters
What is an example of Large Scale Integration (LSI)?
Small embedded processors
What is an example of Very Large Scale Integration (VLSI)?
Complex processors
