M68HC05 Family — Understanding Small Microcontrollers

Freescale Semiconductor, Inc...
Basic Logic Elements
Freescale Semiconductor, Inc.
Although this is a simple logical function, it shows how CMOS transistors
can be interconnected to perform Boolean logic on simple logic-level
signals. Boolean logic is a 2-valued (0 and 1) algebraic system based on
mathematical forms and relationships, and is named for the Irish
mathematician who formulated it.
NOR Gate Figure 6 shows the logic symbol, a truth table for a CMOS NOR gate,
and a CMOS equivalent circuit. When neither input [1] nor input [2] of a
NOR gate is a logic-level 1 signal, the output [3] will be a logic 1. If any
input to a NOR gate is a logic 1, the output will be a logic 0.
[1]
[2]
Input Output
[1] [2] [3]
0 0 1
0 1 0
1 0 0
1 1 0
M68HC05 Family — Understanding Small Microcontrollers — Rev. 2.0
[3]
Figure 6. CMOS NOR Gate
42 Basic Logic Elements
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MOTOROLA
[1]
[2]
[7]
V DD
[6]
[4]
[5]
[3]