Activity 8 - The Little Monkey's mirror chamber (Equality with AND/OR/NOT)

Navigation:

Nuvi dressed as a little monkey

Introduction

In the hall of reflections, the Little Monkey explains:

“To activate the chamber, the signals must match.
If A and B are equal, the door opens.”

Decorative pattern for the logic workshop

Logical goal

Build an output that equals 1 when A = B, using AND/OR/NOT:

See full truth table

A	B	NOT A	NOT B	A AND B	(NOT A AND NOT B)	Output
0	0	1	1	0	1	1
0	1	1	0	0	0	0
1	0	0	1	0	0	0
1	1	0	0	1	0	1

Landscape of the magic forest

Simulator instructions

1. Place

Inputs: A, B
NOT Gate (x2)
AND Gate (x2)
OR Gate
Output

Visual example of the XNOR circuit using AND, OR, and NOT with two inputs and one output

2. Connect

A ➔ NOT: NOT_A
B ➔ NOT: NOT_B
A and B ➔ AND1 (branch “both 1”)
NOT_A and NOT_B ➔ AND2 (branch “both 0”)
AND1 and AND2 ➔ OR
OR ➔ Output

3. Test

Try 00, 01, 10, 11.
The output should be 1 for 00 and 11.

Victory condition: output = 1 if and only if A and B match.

Quick tips

If the output is 1 for 01 or 10, check the cables from NOT_A/NOT_B to AND₂.
Keep the two branches symmetrical so the circuit is easy to read.

Simulator

What did you learn?

How to build the “they are equal” condition using only AND/OR/NOT.
How to use parallel branches to cover complementary cases.

You did it!
Workshop complete