The MC14521B consists of a chain of 24 flip-flops with an input circuit that allows three modes of operation. The input will function as a crystal oscillator, an RC oscillator, or as an input buffer for an external oscillator. Each flip-flop divides the frequency of the previous flip-flop by two, consequently this part will count up to 224 = 16,777,216. The count advances on the negative going edge of the clock. The outputs of the last seven-stages are available for added flexibility.