## PHYS345 Electricity and Electronics

**Hint for 13-35**
First make a circuit that adds one bit from the number **A**
and a corresponding bit from number **B**.
After the circuit module for adding corresponding bits is available, an adder for four bits
may be assembled from four such single-bit adder modules.

Don't forget that a carry bit input,
name it **C**_{i} should be included to incorporate overflow
from the preceding addition of lower-significance bits.

Also note that you will need two output bits, one for the sum bit **S**
and the other for the carry bit output **C**_{o}.

"http://www.physics.udel.edu/~watson/phys345/protected/exercises/hints/13-35a.html"

Last updated Nov. 8, 1999.

Copyright George Watson, Univ. of Delaware, 1999.