If you are a collector or need a running OS, buy a used T5120 server . If you are a hardware engineer, download the Verilog RTL files from Oracle's OpenSPARC page to study the multi-threading architecture.
Hobbyists often use high-end FPGA boards (like the Pano Logic G2 or Xilinx evaluation boards) to "burn" SPARC cores into programmable logic. opensparc t2 buy
You can download the Verilog RTL (Register Transfer Level) code for the OpenSPARC T2 directly from Oracle's website for free. If you are a collector or need a