JMicron JMB321 is a single chip. It integrated six independent SATA channels and a micro-processor.
With proper setting, the chip can be configured as an 1 to 5-ports Serial ATA II Port Multiplier or a 5 to 1-port Serial ATA II Port Selector.
JMB321 contains 15 GPIOs which can be configured as various standard interfaces. It also has the capability to load external firmware code to extendits functionality.