Adders

Question 1

Name 5 N-Bit parallel adder architectures, in descending order of critical path (i.e. longest delay to shortest delay):

Answer 1

1. Ripple-Carry Adder 2. Carry-Bypass Adder 3. Linear Carry-Select Adder 4. Square root Carry-Select Adder 5. Carry-Lookahead Adder

Question 2

Binary Addition rules:

Answer 2

0 + 0 + 0 = 0 carry 0 0 + 0 + 1 = 1 carry 0 0 + 1 + 1 = 0 carry 1 1 + 1 + 1 = 1 carry 1

Question 3

Generate =

Answer 3

AB i.e. Generate signal when both inputs true

Question 4

Propagate =

Answer 4

A _XOR B

Propagate when EITHER A or B is true

Question 5

Delete =

Answer 5

AB (A^not, B^not)

Delete when neither A or B is true