mod 13 sync

This 4-bit digital counter is a sequential circuit that uses JK flipflops, AND gates, and a digital clock. For each clock tick, the 4-bit output increments by one. After it reaches it's maximum value of 15 (calculated by 2^4-1), it resets to zero. Each probe measures one bit of the output, with PR1 measuring the least significant bit and PR4 measuring the most significant bit. PR5 is the clock.