ENEE 408C Lab Capstone Project: Digital System Design Spring 2006

1. ENEE 408C LabCapstone Project: Digital System DesignSpring 2006 Class Web Site: http://www.ece.umd.edu/class/enee408c

2. TA’s Information Alessandro Geist ageist@umd.edu Office Hours: TBD

3. Carry-Save Multiplier Example • Multiply the two 4-bit binary numbers: 1110 B x 0101 A ?

4. Initialize Carry-Save Multiplier P Carry Bits 0 0 0 0 0 1 0 1 Sum Bits 0 0 0 0 A A A A A Choose B based on LSB of A 1 1 1 0 B

5. Step 1: Combinational Addition Outcome P Carry Bits 0 0 0 0 0 1 0 1 Sum Bits 0 0 0 0 A 0 1 0 1 0 1 0 0 A A A A 1 1 1 0 B

6. Step 2: Sequential Shift P Carry Bits 0 0 0 0 0 0 1 0 Sum Bits 1 1 1 0 A A A A A Choose next B based on LSB of A 0 0 0 0 B

7. Step 2: Combinational Addition P Carry Bits 0 0 0 0 0 0 1 0 Sum Bits 1 1 1 0 A 0 0 0 1 0 1 0 1 A A A A 0 0 0 0 B

8. Step 3: Sequential Shift P Carry Bits 0 0 0 0 1 0 0 1 Sum Bits 0 1 1 1 A A A A A Choose next B based on LSB of A 1 1 1 0 B

9. Step 3: Combinational Addition P Carry Bits 0 0 0 0 1 0 0 1 Sum Bits 0 1 1 1 A 0 1 0 1 1 0 0 1 A A A A 1 1 1 0 B

10. Step 4: Sequential Shift P Carry Bits 0 0 1 0 1 1 0 0 Sum Bits 1 1 0 1 A A A A A Choose next B based on LSB of A 0 0 0 0 B

11. Step 4: Combinational Addition P Carry Bits 0 0 1 0 1 1 0 0 Sum Bits 1 1 0 1 A 0 0 0 1 1 0 0 0 A A A A 0 0 0 0 B

12. Step 5: Sequential Shift P Carry Bits 0 0 1 0 0 1 1 0 Sum Bits 0 1 0 0 A A A A A 0 0 0 0 B

13. Final Step Add these together P Carry Bits 0 0 1 0 0 1 1 0 Sum Bits 0 1 0 0 A A A A A 0 0 0 0 B

14. Final Step • Add the Sum and Carry of P using a CPA-type Adder Sum: + 010 Carry: 0010 0100 • Concatenate with A Product = 0100 0110