Elenco Understanding Logic Gates and Circuits User Manual download pdf (Page 25)

U16

U20

Project 15: Half Adder

This circuit demonstrates how a half adder

works. Turn the slide switch (S1) on. The

green LED represents the Sum (S) and the red

LED represents the Carry (C). When the loose

ends of the red and black wires are both

connected to 0 (0+0), both LEDs are off

(S=C=0). When one of the loose ends of the

red and black wires are connected to different

inputs (one to 0 and the other to 1), the green

LED is on and the red LED is off (S=1, C=0).

When the loose ends of the red and black

wires are both connected to 1 (1+1), the green

LED is off and the red LED is on (S=0, C=1)

indicating an overflow condition.

Adders are used

in computers and processors as arithmetic logic units,

as well as to calculate addresses, table indices, etc..

Input (A) Input (B) Output (S) Output (C)

0 0 0 0

0 1 1 0

1 0 1 0

1 1 0 1

Represents the

Sum

Represents the

Carry

1 2 ... 20 21 22 23 24 25 26 27 28 29 30 ... 41 42

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Elenco Understanding Logic Gates and Circuits User Manual Page 25