Logic Experiment 4

老師：伍紹勳助教：江長庭 鄭仲傑

BCD Adder

• Equipment ：– IC ： 7408 x 1 、 7432 x 1 、 7483 x

2 、 7447(DCBA) x 1 、 LED x 1 、 7-Segment LED x 1

Review BCD number addition

• Two units digit decimal number

ex: 7+8=15

BCD :

0 1 1 1

+1 0 0 0

1 1 1 1

+0 1 1 0

0 0 0 1 0 1 0 1

Determine whether to add 6 or not !!!!

>9 => add 6

Tens digit Units digit

Binary Sum BCD Sum K T8 T4 T2 T1 C S8 S4 S2 S1

0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 0 1 0 0 0 0 1 1 2 0 0 0 1 0 0 0 0 1 0 2 3 0 0 0 1 1 0 0 0 1 1 3 4 0 0 1 0 0 0 0 1 0 0 4 5 0 0 1 0 1 0 0 1 0 1 5 6 0 0 1 1 0 0 0 1 1 0 6 7 0 0 1 1 1 0 0 1 1 1 7 8 0 1 0 0 0 0 1 0 0 0 8 9 0 1 0 0 1 0 1 0 0 1 9 A 0 1 0 1 0 1 0 0 0 0 10 B 0 1 0 1 1 1 0 0 0 1 11 C 0 1 1 0 0 1 0 0 1 0 12 D 0 1 1 0 1 1 0 0 1 1 13 E 0 1 1 1 0 1 0 1 0 0 14 F 0 1 1 1 1 1 0 1 0 1 1510 1 0 0 0 0 1 0 1 1 0 1611 1 0 0 0 1 1 0 1 1 1 1712 1 0 0 1 0 1 1 0 0 0 1813 1 0 0 1 1 1 1 0 0 1 19

When to add 6?

1. T8 T4 T2 T1 > 9

00 01 11 10

00

01

11 1 1 1 1

10 1 1

T8T4

T2T1

T8T4 + T8T2

2. Carry is 1

F = T8T4 + T8T2 + K

IC 7483 ( 4-bits full adder )

7-Segment LED

ab

cd

e

fg

dp

Vcc

Vcc

IC 7447

A,K connect to +5Vdp not connect

務必加上電阻

22 ohm

Requirement

• Two units digit decimal number addition in BCD

Input : two BCD number

Output : units digit – 7-Segment LED

tens digit – LED

Input 不能大於 9

T8T4 + T8T2 + K

Tens Digit ( LED )

Units Digit

Add 6 or not

A,K connect to +5Vdp not connect

Input