By clocking the state machine adress pins a2, a1 and a0 change their values every 12 clocks. Shift/load pin is set to 1 and then back to zero every 12 clocks. Other outputs are used for debugging.
After an impulse on reset pin and a subsequent impulse on the ovf pin, you can start clocking the circuit. Adress pins marked with "a" should follow the sequence: "100"->"000"->"001"->"010"->"011"->"000". Shift/load pin wil be set to 1 after every adress change and then set back to 0 on the next clock. The sequence will repeat itself.
| # | Input | Output | Bidirectional |
|---|---|---|---|
| 0 | reset | counter flop1 | a2 |
| 1 | ovf | counter flop2 | a1 |
| 2 | clk | counter flop3 | a0 |
| 3 | bi oe | counter flop4 | shift/load |
| 4 | zero | sm flop1 | |
| 5 | one | sm flop 2 | |
| 6 | global reset | sm flop 3 | |
| 7 | ovf | sm flop 4 |