lesson 2
TRANSCRIPT
Lessons: IC’s and Gates
Priscilla M. SoteloInstructor, Digital Design Lab
Inspiration Motivation Lesson Proper Assignment/
Announcement/Reminders
Agenda
“The only way to do great work is to love what you do,” says Steve Jobs. “If you
haven’t found it yet, keep looking. Don’t
settle.”
Motivation
Integrated Circuit
Small Scale Integrated(SSI) 1-
10 Medium Scale Integrated(MSI)
10-100 Large Scale Integrated(LSI)
100-100,000 Very Large Scale
Integrated(VLSI) >100,000
IC Sizes
also called "chips", are electronic
circuits where all the components (transistors, diodes, resistors and capacitors) has been manufactured in the surface of a thin substrate of semiconductor material.
All ICs (chips) are made up of logic gates
These are square pieces of silicon onto which logic gates have been deposited.
Integrated Circuit
I.C can work on low voltages. They can handle limited amount of power. They are very small in size They are cheap Complex circuitry on a chip may be used to
obtain improved performance characteristics.
Integrated Circuits (IC’s)
Example of SSI Chip – Logic Gates
Example of MSI Chip - Multiplexer
Example of VLSI Chip - CPU
process signals which
represent true or false Normally the positive supply
voltage +Vs represents true and 0V represents false.
Logic Gates
Switches in Series
If several on-off switches are
connected in series they must all be closed (on) to complete the circuit.The diagram shows a simple circuit with two switches connected in series to control a lamp.
Switch S1 AND Switch S2 must be closed to light the lamp.
Switches in Series
Switches in Parallel
If several on-off switches are
connected in parallel only one needs to be closed (on) to complete the circuit.The diagram shows a simple circuit with two switches connected in parallel to control a lamp.
Switch S1 OR Switch S2 (or both of them) must be closed to light the lamp.
Switches in Parallel
The output Q is true if input A AND input B are both true: Q = A AND B An AND gate can have two or more inputs, its output is true if all inputs are true.
AND gate
The output Q is true if input A OR input B is true (or both of them are true): Q = A OR B An OR gate can have two or more inputs, its output is true if at least one input is true.
OR gate
The output Q is true when the input A is NOT true, the output is the inverse of the input: Q = NOT A A NOT gate can only have one input. A NOT gate is also called an inverter.
NOT gate (inverter)
This is an AND gate with the output inverted, as shown by the 'o' on the output. The output is true if input A AND input B are NOT both true: Q = NOT (A AND B) A NAND gate can have two or more inputs, its output is true if NOT all inputs are true.
NAND gate (NAND = Not AND)
This is an OR gate with the output inverted, as shown by the 'o' on the output. The output Q is true if NOT inputs A OR B are true: Q = NOT (A OR B) A NOR gate can have two or more inputs, its output is true if no inputs are true.
NOR gate (NOR = Not OR)
The output Q is true if either input A is true OR input B is true, but not when both of them are true:Q = (A AND NOT B) OR (B AND NOT A) This is like an OR gate but excluding both inputs being true. The output is true if inputs A and B are DIFFERENT. EX-OR gates can only have 2 inputs.
EX-OR (EXclusive-OR) gate
This is an EX-OR gate with the output inverted, as shown by the 'o' on the output. The output Q is true if inputs A and B are the SAME (both true or both false):Q = (A AND B) OR (NOT A AND NOT B) EX-NOR gates can only have 2 inputs.
EX-NOR (EXclusive-NOR) gate
Summary for all 2-input gates
Inputs Output of each gate
A B AND NAND
OR NOR EX-OR
EX-NOR
0 0 0 1 0 1 0 1
0 1 0 1 1 0 1 0
1 0 0 1 1 0 1 0
1 1 1 0 1 0 0 1
is a breakdown of a logic function by listing all possible values the function can attain.
Truth Table
That’s all for today
Take care!Enjoy your weekend!
Always remember that “God loves you!”
http://www.kpsec.freeuk.com/gates.htm#and
Reference