It is called a BCD counter because its ten state sequence is that of a BCD code and does not have a regular pattern, unlike a straight binary counter. Then a single stage BCD counter such as the 74LS90 counts from decimal 0 to decimal 9 and is the refore capable of counting up to a maximum of nine pulses. Note also that a digital counter may count up or count down or count up and down (bidirectional) depending on an input control signal.