We found a pretty unique project that was covered recently over at Hackaday, involving a hacked-together 8-bit retro-styled computer. The kicker here is that it was made using an FPGA combined with VHDL inplementations of classic CPUs such as the 6502, 6809, and Z80.
In its full configuration, the Multicomp, as [Grant] calls his project, includes either a 6502 (pictured above), 6809, Z80, or (in the future) a 6800 CPU. Video options include either monochrome RCA, RGB VGA, or RGB via SCART. This, along an SD card interface, a PS2 keyboard, and the ability to connect an external 128kB RAM chip (64k available) means it’s a piece of cake to build a proper and complete portable retrocomputer.
In this project, the data and address lines are fully exposed from the FPGA. That means that you could add whatever circuit you want to make whatever old-school computer you can think of!
Here’s a link to Grant’s site, where he’s got an absolute wealth of info on the project, code, and more. He’s going to show you exactly what you need to do to create your own retro computer with your FPGA! There is also more information on this over at the 6502.org forums
(via Grant’s site)