Binary Addition/Subtraction Flashcards Preview

Digital System Design 2 > Binary Addition/Subtraction > Flashcards

Flashcards in Binary Addition/Subtraction Deck (11):
1

What are the boolean algebraic formula for the output of a 2-input half adder?

Carry = A . B

Sum = A XOR B

2

What is the difference between a half adder and a full adder?

A full adder has a Carry In in addition.

3

What are the boolean algeberaic formulae for the output of a full adder?

Sum = A XOR B XOR CIN

CarryOUT = A.B + A.CIN + B.CIN

 

4

Draw the symbolic box diagram for a 2 input Full Adder showing all inputs and outputs

5

Draw the box diagram showing how to connect full adders to add together two 4-bit numbers

6

How do you calculate the propagation delay for a ripple carry adder?

7

Draw the truth table for a full adder, mentioning carry status at each line.

8

How do we subtract two numbers using full adders?

A + (-B)

We take the 2's complement of B and add with A

We wary of overflow and underflow

9

How do we detect overflow when dealing with subtraction/ 2's complement?

Overflow if the carry out is different to the carry in

Overflow = CIN XOR COUT

10

Draw a 4-bit subtracter

11

Using XOR gates and a bitinvert signal show how you can design one circuit that can add or subtract two 4-bit numbers.