Fix the ALU and properly test it (including difference, not just sign output).
treeb988d3f243a75768f10727a61075f283e0122f7f
-rwxr-xr-x 32 .gitignore
-rwxr-xr-x 274432 Spring 2008 Schedule.mpp
-rwxr-xr-x 380416 Summer 2008 Schedule.mpp
drwxr-xr-x - asm
drwxr-xr-x - bb
drwxr-xr-x - circuits
drwxr-xr-x - digital_simulator
drwxr-xr-x - tools