A key benefit of DPP technology is that by providing capacity expansion, DPP technology allows point-to-point upgrades at full memory system bandwidth. DPP technology can be applied to many different types of memory technologies, including DDR4 and beyond. In an example 32-bit DDR3 memory system, the base system configuration has a single memory module, with this module supplying all of the memory bandwidth across the full datapath width. A continuity module occupies the second memory slot, providing electrical continuity that maintains the point-to-point connection across half of the datapath.
When the continuity module is removed and an expansion module is added, the datapath is reconfigured to supply memory bandwidth from both modules. In this example, each module supplies half of the memory system bandwidth across a different half of the datapath in a point-to-point topology. Using DPP technology, the single 32-bit module is “dynamically rewired” to become a 16-bit module when the second module is added. In order to accomplish this the width of the memory devices on the module must change from x4 DRAMs to X2 DRAMs in the upgraded module configuration. In the x4 mode, each DRAM supplies four bits of data, two bits directly to the ASIC and two bits through the continuity module to the ASIC. When an upgrade module is inserted, the path through the continuity module is broken and the devices switch to x2 mode. In x2 mode, each DRAM supplies two bits of data directly to the ASIC.