74LS257 Quad 2-Input Multiplexer

Spec Sheet
74LS257_B6_B7_A8

AMD

From a photo of Rev. 0 board 1070 (A2S1-0800), near locations A8, B6 and B7. There are others near locations C12 and J1. 
SN74LS257N, 7737M date code.
Total # on board: 5.