The document is a technical datasheet for the United Microelectronics Corporation (UMC) part number UM74HCT646. It details the device as an Octal Bus Transceivers and Register featuring bi-directional data bus transmission, three-state outputs, and compatibility with 74LS logic families.
The maximum access time is 450 ns.
It supports a single +5V power supply with +/- 5% tolerance.