The JM388D643A-5L is a 128Mx64bits Double Data Rate SDRAM high-density Module for DDR400. The JM388D643A-5L consists of 16pcs CMOS 64Mx8 bits Double Data Rate SDRAMs in 66 pin TSOP-II 400mil packages and a 2048 bits serial EEPROM on a 184-pin printed circuit board. The JM388D643A-5L is a Dual In-Line Memory Module and is intended for mounting into 184-pin edge connector sockets. Synchronous design allows precise cycle control with the use of system clock. Data I/O transactions are possible on both edges of DQS. Range of operation frequencies, programmable latencies allow the same device to be useful for a variety of high bandwidth, high performance memory system applications.