CERBERUS 2080™, the amazing multi-processor 8-bit microcomputer: a fully open-source project available for anyone to peruse, build, modify, extend, have fun with, write software for, or commercialize. You owe me nothing but an acknowledgment of original authorship, should you choose to use it. Everything you need to know is in the files /CERBERUS 2080 Complete Manual V1.2.pdf and /CERBERUS 2080 BoM R1.1.pdf. (The PDF preview on Github doesn't work well for the Manual: it starts repeating pages towards the end of the file. To avoid confusion, you can simply download the PDF file and view it locally.)
You can buy a CERBERUS 2080 kit, with pre-programmed CPLDs and microcontroller, from the Home Computer Museum. All you need to do is solder the components, which are all through-hole parts relatively easy to solder. But if you prefer, you can also buy a pre-assembled unit from the museum, using the same link above. In either case, you will be contributing to a registered public-interest nonprofit dedicated to preserving the history of computers, as 100% of the proceeds go to the museum, none to me.
There is a Facebook Group dedicated to all things CERBERUS. Andy Toone's fork of this repository contains an enhanced BIOS with several extra features handy for game development. Have a look there. HACKADAY has also published an article on CERBERUS.
The official page of the CERBERUS 2080™ project can be found here.
You can also watch the entire design and build process of CERBERUS 2080™, with in-depth commentary and explanations for every design decision, in a series of videos on my YouTube channel.
02 July 2021: (1) Page 41 of the Manual has been updated to inform the user how to pause and step through the CELL application. (2) Github directory name changed from "CPLD Files" to "CPLD_Files" because CUPL doesn't recognize spaces in directory names. (3) The tabulations of all three .PLD files have been re-formatted for better readability. (4) The buried logic nodes are now left unassigned to pins in CAVIA.PLD and SKUNK.PLD as well, not only in SPACER.PLD. This way, the CUPL compiler makes the assignments automatically. The functionality didn't change at all, but the .PLD files are now easier to interpret.
23 June 2021: (1) BoM updated (10+6mm nylon standoffs also work, not only 12+6mm, as originally stated). (2) The Manual has also been updated for convenience and cosmetic reasons, but no change in substance.