In March 2006, the complete design of Sun Microsystems' UltraSPARC T1 microprocessor was released-in open-source form, it was named OpenSPARC T1. In early 2008, its successor, OpenSPARC T2, was also released in open-source form. These were the first (and still only) 64-bit microprocessors ever open-sourced. They were also the first (and still only) CMT (chip multithreaded) microprocessors ever open-sourced. Both designs are freely available to anyone under open-source licenses. These downloads include not only the processor design source code but also simulation tools, design verification suites, Hypervisor source code, and other helpful tools. Variants that easily synthesize for FPGA targets are also available.