同源大学 TONGJI UNIVERSITY Qs Q4 Q2 Q1 Os Q4 0201 Qs Q4 Q2O1 BCD BCD BCD Count Counter Counter Counter pulses 102 digit 101 digit 100 digit Fig.6-11 Block Diagram of a Three-Decade Decimal BCD Counter 2002 Prentice Hall,Inc. M.Morris Mano DIGITAL DESIGN,3e