ain - Puts a value into register A. bin - Puts a value into register B. cin - Puts a value into register C. din - Don't know why we need a fourth register, but this puts a value into register D. add - Has 2 inputs and 1 output. Adds together the 2 inputs and outputs it into a register. sub - Pretty much the same as add, but it subtracts. Even though this is a demo, it took a longer time than i expected. Has 3 bits of memory.