In these slides the concept of BCD or Decimal Adder have explained in detail with the add of animations so that user may understand the concept easily. at the end the demonstration has also made to understand the working of BCD adder in a better way.

1. BCD Adder
UNIT-2
Mohammad Asif Iqbal
Assistant Professor,
Deptt of ECE,
JETGI, Barabanki

2. BCD ADDER

3. BCD Adder. Lest design…
A1 A2 A3 A4 B1 B2 B3 B4
0 0 0 0 0 0 0 0
1 1 1 1 1 1 1 1
512
COMBINATIONS
IS IT NOT VERY
TEDIOUS???

4. BCD Adder
So before heading towards the new approach, lest again discuss the HIGHEST possible
number in addition of two 4-bit BCD
HIGHEST NUBER USING 4-BIT BCD- 9
HIGHEST NUBER USING 4-BIT BCD- 9
DON’T FORGET TO INCLUDE THE CARRY OF PREVIOUS STAGE-1
19

5. Bcd adder (sum up to 9)
Number C S3 S2 S1 S0
0 0 0 0 0 0
1 0 0 0 0 1
2 0 0 0 1 0
3 0 0 0 1 1
4 0 0 1 0 0
5 0 0 1 0 1
6 0 0 1 1 0
7 0 0 1 1 1
8 0 1 0 0 0
9 0 1 0 0 1

6. Bcd adder (sum is 10 to 19)
Number C S3 S2 S1 S0
10 1 0 0 0 0
11 1 0 0 0 1
12 1 0 0 1 0
13 1 0 0 1 1
14 1 0 1 0 0
15 1 0 1 0 1
16 1 0 1 1 0
17 1 0 1 1 1
18 1 1 0 0 0
19 1 1 0 0 1

7. Bcd adder (sum is 10 to 19)
BCD adder sum Binary sum
Number
C S3 S2 S1 S0
10 1 0 0 0 0
11 1 0 0 0 1
12 1 0 0 1 0
13 1 0 0 1 1
14 1 0 1 0 0
15 1 0 1 0 1
16 1 0 1 1 0
17 1 0 1 1 1
18 1 1 0 0 0
19 1 1 0 0 1
K s3 s2 s1 s0
0 1 0 1 0
0 1 0 1 1
0 1 1 0 0
0 1 1 0 1
0 1 1 1 0
0 1 1 1 1
1 0 0 0 0
1 0 0 0 1
1 0 0 1 0
1 0 0 1 1

8. When is the result>9
Binary sum
Number K S3 S2 S1 S0
10 0 1 0 1 0
11 0 1 0 1 1
12 0 1 1 0 0
13 0 1 1 0 1
14 0 1 1 1 0
15 0 1 1 1 1
16 1 0 0 0 0
17 1 0 0 0 1
18 1 0 0 1 0
19 1 0 0 1 1
C = K +

9. When is the result>9
Binary sum
Number K S3 S2 S1 S0
10 0 1 0 1 0
11 0 1 0 1 1
12 0 1 1 0 0
13 0 1 1 0 1
14 0 1 1 1 0
15 0 1 1 1 1
16 1 0 0 0 0
17 1 0 0 0 1
18 1 0 0 1 0
19 1 0 0 1 1
C = K + S3*S2+

10. When is the result>9
Binary sum
Number
K S3 S2 S1 S0
10 0 1 0 1 0
11 0 1 0 1 1
12 0 1 1 0 0
13 0 1 1 0 1
14 0 1 1 1 0
15 0 1 1 1 1
16 1 0 0 0 0
17 1 0 0 0 1
18 1 0 0 1 0
19 1 0 0 1 1
C = K + S3*S2+
S3*S1

11. 0 0 1 1
0 1 0 1
0 1 0 0 0
0
00
1 0 0 0
0 0 0 0
Inputs:[A]=0101, [B]= 0011, Co=0
1 0 0 0
1

12. THANK YOU!