Processor Local Memory Controllers Both the PCI-X PowerPC and Serial RapidIO PowerPC each have their own dedicated DDR memory controllers, each with 128MB of DDR SDRAM. The memory controllers perform device initialization upon power-up and reset conditions. They support auto-refresh cycles, single-beat and burst transactions, and target-word first cache-line transactions. Each local DDR array is arranged in a 32Mx32-bit configuration.