Question

How do I design a BCD to seven-segment decoder using a single decoder and OR gates only?

Answer 1

Truth Table:

let A = SW3, B = SW2, C = SW1, D = SW1

1. The truth table is attached in mage below. abcdefg are the 7 outputs of seven segment display.

2. K-maps of all 7 outputs is also attached as image to this response.

3. Outputs of seven segment display as SOP are as follows =

a = ~B~D + C + BD + A

b = ~B + ~C~D +CD

c =  ~C +D +B

d = ~B~D + ~BC + B(~C)D + C(~D) + A

e =  ~B~D + C~D

f =  ~C~D + B(~C) +B(~D) + A

g =  ~BC + B(~C) + A + B(~D)