Information about Apple's implementation of Open Firmware.
http://bananajr6000.apple.com/
32-bit microprocessor architecture developed to serve as the main hardware building block of the real-time TRON Hypernetwork (Highly Functional Distributed System: HFDS), which is the ultimate goal of the TRON Project.
http://tronweb.super-nova.co.jp/tronvlsicpu.html
Mixed German-English site at Munich University of Applied Sciences. MMIX extensions: MMIXAL LaTeX output, Win32 graphical output.
http://www.informatik.fh-muenchen.de/~mmix/
O-F is done in Forth.
http://www.firmworks.com/www/ofw.htm
Donald E. Knuth's new 64-bit processor for the new volumes of his landmark series: 'The Art of Computer Programming'. But might MMIX become more than only a book example.
http://www-cs-faculty.stanford.edu/~knuth/mmix.html
32-bit, 2-way superscalar RISC processor, designed in a HDL. Source downloads. This one is actually working.
http://www.asahi-net.or.jp/~uf8e-itu/
O-F is processor and system independent boot code: firmware. Read about O-F, the Working Group; several related documents; several links to mirror sites, Forth, vendors, documentation, news, and proposals.
http://playground.sun.com/1275/
For advanced hobbyists: share free microprocessor and DSP IP cores written in Verilog or VHDL.
http://www.cmosexod.com/