The HB52E649E12 belongs to 8-byte DIMM (Dual In-line Memory Module) family, and has been developed as an optimized main memory solution for 8-byte processor applications. The HB52E649E12 is a 64M x 72 x 1-bank Synchronous Dynamic RAM Registered Module, mounted 18 pieces of 256-Mbit SDRAM (HM5225405BTT) sealed in TSOP package, 1 piece of PLL clock driver, 2 pieces of register driver and 1 piece of serial EEPROM (2-kbit) for Presence Detect (PD). An outline of the HB52E649E12 is 168-pin socket type package (dual lead out). Therefore, the HB52E649E12 makes high density mounting possible without surface mount technology. The HB52E649E12 provides common data inputs and outputs. Decoupling capacitors are mounted beside each TSOP on the module board.