What this 16-bit buffer/inverter does on a 5V bus
The 74ACT16240DL is a 16-bit inverting buffer with 3-state outputs from the 74ACT family, designed for 5V bus-oriented systems. The four independent 4-bit sections let you gate individual byte lanes or combine them for a full 16-bit wide bus. The 3-state outputs allow multiple devices to share a common data bus — when the output enable is inactive, the pins go high-impedance and don't load the line. This is the standard arrangement for memory address buffers, peripheral chip-select gating, or any bidirectional bus where the buffer only drives when selected.
The 74ACT process gives faster edge rates than the original 74AC series, which matters when the bus clock runs above 25 MHz — but those fast edges also mean you should keep trace lengths short and add a series damping resistor if the line is longer than a few inches.