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The XSB Southbridge
IntroducedLate 2005
Designed ByMicrosoft
Used InXbox 360

The Southbridge is the IO controller used in the Xbox 360. It contains interfaces for peripherals, audio output/decompression, drives, and memory units. It also contains the flash interface and System Management Controller. The later KSB variant also has the HANA's functionality built in.

The chip was developed by Microsoft and SiS.


  • Intel 8051 processor core (SMC)
  • PCI-Express x2 interface (for the BSB)
  • Serial-ATA (SATA) interface
  • USB1.1/2.0 interface
  • IR interface
  • Wireless game controller interface (for the RF Board)
  • WMA Pro audio hardware
  • Nand flash interface
  • Ethernet Media Access Controller (MAC)



The XSB (Xenon SB) is the initial version of the Southbridge and is used on the Xenon, Zephyr, and Falcon motherboards.


The PSB (Panda SB) is the second version of the Southbridge and is used on the Jasper and Trinity motherboards.


The KSB (Koala SB) is the final version of the Southbridge and is used on the Corona and Winchester motherboards. It includes the functionality previously provided by the HANA, such as clock generation and video encoding.