在74HC/HCT/HCU高速CMOS(HCMOS)逻辑集成电路系列采用之前,高速逻辑系统的设计者被限制在使用诸如LSTTL的这种功耗大的双极性集成电路。由于HCMOS系列的逻辑集成电路的工作速度快得与LSTTTL一样,而所消耗的平均功率要小得多,并由于其可在较宽的电源电压范围内工作,用HGMOS来代替LSTTL的结果是对新的和现有的逻辑 Before the introduction of the 74HC / HCT / HCU high-speed CMOS (HCMOS) logic integrated circuit family, designers of high-speed logic systems were limited to using such power-hungry bipolar integrated circuits such as the LSTTL. Since the HCMOS family of logic ICs operate as fast as LSTTTLs and consume significantly less average power and because they can operate over a wider range of supply voltages, the result of replacing the LSTTLs with HGMOS is New and existing logic