| .model test | |
| .inputs A0 A1 B0 B1 start c | |
| .outputs C0 C1 C2 | |
| .subckt FA a=A0 b=A1 c=start carryout=CARRY1 sum=C0d | |
| .subckt FA a=A1 b=B1 c=CARRY1 carryout=C2d sum=C1d | |
| .latch C0d C0 re c 0 | |
| .latch C1d C1 re c 0 | |
| .latch C2d C2 re c 0 | |
| .end | |
| .model FA | |
| .inputs a b c | |
| .outputs carryout sum | |
| # test | |
| .blackbox extra words | |
| .end |