This part is a kind of semiconductor called 74645.

Function of this product has Octal Bus Transceiver.

Manufacturers : Fairchild Semiconductor

Image and pinout :

Some of the text within the PDF file :

DM74LS645 Octal Bus Transceiver August 1986 Revised March 2000 DM74LS645 Octal Bus Transceiver General Description These octal bus transceivers are designed for asynchronous two-way communication between data buses. The devices transmit data from the A bus to the B bus or from the B bus to the A bus depending upon the level at the direction control (DIR) input. The enable input (G) can be used to disable the device so that the buses are effectively isolated. Features s Bi-directional bus transceivers in high-density 20-pin packages s Hysteresis at bus inputs improves noise margins s 3-STATE outputs Ordering Code: Order Number Package Number Package Description DM74LS645WM M20B 20-Lead Small Outline Integrated Circuit (SOIC), JEDEC MS-013, 0.300 Wide DM74LS645N N20A 20-Lead Pla [ ... ]

74645 PDF Datasheet Download