4-Bit Calculator V. 4

This is a calculator that takes inputs from 0-15 and adds, subtracts, and multiplies.Takes an input through decimal and encodes it in BCD (Binary-Coded Decimal). The BCD is saved and displayed for the user to see what they are entering on the board. The user can choose either addition, subtraction, or multiplication. The BCD for each number is then translated into binary. The binary will then flow through each module based on what operation the user choose. If they choose multiplication, the machine will multiply each digit of the number by each digit of the other number. It will then add them together according to which digit of the product it belongs to. The adder and subtracting machine use the adders at the end of of the multiplier to do their functions. The subtracting machine uses the complement method so it can use adders to subtract. After the signals are through their respective functions, the signal goes through a double dabble machine. It translates the binary into BCD. Each tower in the double dabble machine adds 3 to any signal above 5. This is how it translates it into BCD. After the BCD is done, the signal is sent to the 7 segment product module where it waits to be displayed until the user presses the "Compute" button. Everything will be cleared when the user presses the "Reset" button.