DRAM ram memory, dynamic random access memory, Types of DRAMs, dram chip

 AS4C4M16S Series 256 Mb (16 M x 16) 166 MHz CMOS SDRAM - TSOP II-54

https://www.futureelectronics.com/p/semiconductors--memory--RAM--dram--component-dram/as4c16m16sa-7tcn-alliance-memory-8053243