25-08-2017, 09:32 PM
logic and computer design fundamental
05-AdditionalGates.ppt (Size: 412 KB / Downloads: 43)
NAND Gate
The basic NAND gate has the following symbol and truth table:
AND-Invert (NAND) Symbol:
NAND represents NOT AND. The small “bubble” circle represents the invert function
The NAND gate is implemented efficiently in CMOS technology in terms of chip area and speed
NAND Gate: Invert-OR Symbol
This NAND symbol is called Invert-OR
Since inputs are inverted and then ORed together
AND-Invert & Invert-OR both represent NAND gate
Having both makes visualization of circuit function easier
Unlike AND, the NAND operation is NOT associative
(X NAND Y) NAND Z ≠ X NAND (Y NAND Z)
NOR Gate
NOR represents NOT OR. The small “bubble” circle represents the invert function.
The NOR gate is also implemented efficiently in CMOS technology in terms of chip area and speed
The NOR Gate is also Universal
NOR gates can implement any Boolean function
NOR gates can be used as inverters, or to implement AND / OR operations
A NOR gate with one input is an inverter
OR is equivalent to NOR with inverted output