The HC240 and HCT240 are inverting three-state buffers having two active-low output enables. The CD74HC241, HCT241, HC244 and HCT244 are non-inverting three-state buffers that differ only in that the 241 has one active-high and one active-low output enable, and the 244 has two active-low output enables. All three types have identical pinouts.