This part is a kind of semiconductor called AS4C8M16S-6TCN.

Function of this product has 128M - 8M x 16 bit Synchronous DRAM.

Manufacturers : Alliance Semiconductor

Image and pinout :

Some of the text within the PDF file :

AS4C8M16S 128M - 8M x 16 bit Synchronous DRAM (SDRAM) Confidential Features Fast access time from clock: 5/5.4 ns Fast clock rate: 166/143 MHz Fully synchronous operation Internal pipelined architecture 2M word x 16-bit x 4-bank Programmable Mode registers - CAS Latency: 2, or 3 - Burst Length: 1, 2, 4, 8, or full page - Burst Type: Sequential or Interleaved - Burst stop function  Auto Refresh and Self Refresh  4096 refresh cycles/64ms  CKE power down mode  Single +3.3V  0.3V power supply  Interface: LVTTL  Operating temperature range - Commercial (0 ~ 70°C) - Industrial (-40 ~ 85°C) - Automotive A2 (-40 ~ 105°C) 54-pin 400 mil plastic TSOP II package   54-ball 8.0 x 8.0 x 1.2mm (max) FBGA package All parts ROHS Compliant       (Rev. 2, Feb. [ ... ]

AS4C8M16S-6TCN PDF Datasheet Download