The SEAD-3 is an evaluation platform made by MIPS Technologies. It is meant to support the development of SOCs so it features logic analyzer connections, a JTAG port and other features to support this specific purpose. Other than that it provides a very barebone environment, two 8250-class UARTs provide the only connectivity to the outside world.
Supported in Linux 2.4 and 2.6 up to 2.6.26. Will be fully supported in the Linux 3.8 release.