http://www.hynix.com/datasheet/pdf/dram/HY57V56820B(L)T(Rev1.4).pdf А ларчик просто открывался...

HY57V56820B(L)T
4 Banks x 8M x 8Bit Synchronous DRAM
DESCRIPTION
The HY57V56820B is a 268,435,456bit CMOS Synchronous DRAM, ideally suited for the main memory applications which require large
memory density and high bandwidth. The HY57V56820B is organized as 4banks of 8,388,608x8.