Simple Calculator (Beta)

This is a simple calculator (not so simple to build) that will only do addition and subtraction of SINGLE DIGITS, but it has a realistic calculator display. I challenged myself to see if I can pull it off, I spent hours trying to debug it so that it loops properly and doesn't overlap numbers etc.

I have limited the input to a single digit, so basically it takes (number/ +or- /number / = / clear)

UPDATE: MADE UP CMP-LE GATES TO INCREASE THE THRESHOLD OF THE COMPARISON GATES SO EVERYTHING SHOULD BE WORKING PROPERLY. (Thanks ZardOZ!)

NOTE: TRY NOT TO PUSH MORE THAN ONE BUTTON AT A TIME, AND DON'T PUSH THE BUTTONS TOO FAST,
ONCE YOU COME ACROSS A GLITCH OR A FALSE OUTCOME, IT JUST MEANS THAT THE LOOPING GOT MIXED UP, JUST RESTART THE LEVEL.