Zilog Z80
https://en.wikipedia.org/wiki/Zilog_Z80

Parallax Propeller
https://en.wikipedia.org/wiki/Parallax_Propeller

On August 6, 2014, Parallax Inc., released all of the Propeller 1 P8X32A hardware and tools as open-source hardware and software under the GNU General Public License (GPL) 3.0. This included the Verilog code, top-level hardware description language (HDL) files, Spin interpreter, PropellerIDE and SimpleIDE programming tools, and compilers.[3]