The machine first uses data flip flops to enter in numbers and prevent spam. Data flip flops are also used in the operation choosing area. The number you pushed the button for will be encoded into binary, and put through comparators that make sure the signal goes to the correct operation. The multiplier will multiply each digit of the binary number by each digit of the other binary number to produce 4 numbers that are then added together to get your product. The adder uses the end of the multiplier where it adds the multiplied values together for when its adding. The switch will shut off multiplication and only input from the adders will get through. Subtraction uses the adders too, by inverting the subtracted number, adding them together, and then inverting the number again. After the final product of one of the 3 operations is found in binary, it is sent through a double dabble algorithm decoder where the binary number is decoded in 3 bcd’s (Binary coded decimal) for each digit. The BCD’s are then decoded into decimal and sent to the corresponding 7 segment display.
Pick 2 numbers to add/subtract/multiply. Pick your operation. When subtracting it is top number minus bottom number. In a couple seconds your answer should appear on the triple 7 segment board.