The "extensible MIPS" is a dynamically extensible processor that offers application-specific hardware in a general-purpose, multiuser system environment. It enables multiple secure extensions to load dynamically and extend the core instruction set of the microprocessor. Extended instructions can speed application programs dramatically just by patching their binaries. The eMIPS prototype is built out of a Xilinx FPGA using the XUP board. Source and software tests are included in this download.