Digital Circuit Fundamentals 1 Unit 5 – 4-BIT Adder
The IC performs binary (or base 2) addition. The base 2 subscript, or radix indicates a binary
weighted number written as number 2 (1000 2 ). Each stage adds its three inputs, generates an
output, and internally sends carry information to the next stage in line.
The fundamental rules of binary addition are given below.
0 + 0 = 0
0 + 1 = 1
1 + 0 = 1
1 + 1 = 0 with a 1 carry or 10
EXAMPLE
0010
- 0101
0111
EXAMPLE WITH A CARRY
0001
- 0001
0010
NEW TERMS AND WORDS
the sum of - a term indicating that numbers are added to generate a sum.
S - a symbol indicating the sum of T.
base 2 - a number expressed in binary form.
radix - a subscript that defines the base of a number.