4-bit addition calculator

Browsing around on Google Play, I found an electronics emulator software called DroidTesla (there are free and paid ones). After I downloaded the free one because I don’t have money for the paid one :p, I was confused about what to do.

Let me think for a bit ｢(ﾟﾍﾟ) first—after checking out the features, it turns out it’s pretty interesting too. I got the idea to make a mini calculator circuit, but it can only do addition—well, I’m a newbie after all.. hehehe.

Rather than taking forever, I just tried the app earlier. I made it limited to 4-bit. So it can only do addition up to 16. The input uses switches that represent binary numbers, 1 if on, 0 if off. The output uses LEDs, and it’s read in binary numbers too.

There are 8 switches; the first 4 are the first number, the next 4 are the second number. For example, 1+2 = 3. That means the first 4 switches are set: ON, OFF, OFF, OFF and the 4 switches after that are set: OFF, ON, OFF, OFF. And later, on the LEDs, the order is OFF, OFF, ON, ON, or it can be read as 0011, which is 3.