Assignment 04
(Hands-On Lab) Full Adder
Part 1 of 2: single bit adders
Given the chips:
- 74LS132
- 74LS136
Construct a 1-bit full adder which satisfies this truth table:
| carry in | A | B | sum | carry out |
|---|---|---|---|---|
| 0 | 0 | 0 | 0 | 0 |
| 0 | 0 | 1 | 1 | 0 |
| 0 | 1 | 0 | 1 | 0 |
| 0 | 1 | 1 | 0 | 1 |
| 1 | 0 | 0 | 1 | 0 |
| 1 | 0 | 1 | 0 | 1 |
| 1 | 1 | 0 | 0 | 1 |
| 1 | 1 | 1 | 1 | 1 |
steps to complete:
- find pinout for each chip
- test all gates on each chip are functional
- wire the circuit on a breadboard
Complications
- 74LS132 contains only NAND. How can we construct a full adder using only XOR and NAND?
- 74LS136 has open-collector outputs. Use a pull-up resistor to provide logic high for each XOR output you use.
Possible Full Adder implementations:
Hints
Connect wires one at a time, double-checking as you go. Debugging circuits with many wires is harder than debugging small circuits with few wires.
Make connections before applying power. A misplaced wire can destroy a chip in milliseconds.