All decade counters are BCD counters.

The 7447 has a 4-bit BCD input, seven individual active-LOW outputs, and a ripple blanking input and output.

In a full-featured counter in HDL, the concept of rolling over simply means the count sequence has reached its limit and must start over at the beginning of the sequence.

One characteristic of a ring counter is that the modulus is equal to the number of flip-flops in the register and, consequently, there are never any unused or invalid states.

When implementing a complete system application using IC counter chips, output devices such as LED indicators must be configured to operate from the counter outputs.