The HYS 72Vxx3xxGR-7 and -7.5 are industry standard 168-pin 8-byte Dual in-line Memory Modules (DIMMs) organized as 16M x 72, 32M x 72, 64M x 72, 128M x 72 and 256M x 72 high speed memory arrays designed with Synchronous DRAMs (SDRAMs) for ECC applications. All control and address signals are registered on-DIMM and the design incorporates a PLL circuit for the Clock inputs. Use of an on-board register reduces capacitive loading on the input signals but are delayed by one cycle in arriving at the SDRAM devices. Decoupling capacitors are mounted on the PC board. The DIMMs use a serial presence detects scheme implemented via a serial E2PROM using the 2-pin I 2C protocol. The first 128 bytes are utilized by the DIMM manufacturer and the second 128 bytes are available to the end user. All Infineon 168-pin DIMMs provide a high performance, flexible 8-byte interface in a 133.35 mm long footprint.