HCMOS ("high-speed
CMOS") is the set of specifications for electrical ratings and characteristics, forming the 74HC00 family, a part of the
7400 series of
integrated circuits.[1]
The 74HC00 family followed, and improved upon, the 74C00 series (which provided an alternative CMOS logic family to the
4000 series but retained the part number scheme and pinouts of the standard
7400 series (especially the 74LS00 series)) .
HCMOS also stands for high-density CMOS.[citation needed] The term was used to describe
microprocessors, and other complex integrated circuits, which use a smaller manufacturing processes, producing more transistors per area. The
Freescale 68HC11 is an example of a popular HCMOS
microcontroller.[2][3]
Variations
HCT stands for high-speed CMOS with
transistor–transistor logic voltages. These devices are similar to the HCMOS types except they will operate at standard
TTL power supply voltages and logic input levels. This allows for direct pin-to-pin compatible CMOS replacements to reduce power consumption without loss of speed.[4]
HCU stands for high-speed CMOS un-buffered. This type of CMOS contains no buffer and is ideal for crystals and other ceramic oscillators needing linearity.[5]
VHCMOS, or AHC, stands for very high-speed CMOS or advanced high-speed CMOS.[6] Typical
propagation delay time is between 3 ns and 4 ns. The speed is similar to Bipolar
Schottky transistorTTL.[7]
AHCT stands for advanced high-speed CMOS with
TTL inputs. Typical
propagation delay time is between 5 ns and 6 ns.[8][9][10]