For seven months, [Bernardo Kastrup] at [TheByteAttic] has been realizing his childhood dream of building his own computer. It was this dream that steered him into the field of computer design at the age of 17. After thirty years in the industry, he finally has some time to design the computer he dreamt about as a kid. His requirements are ambitious: fully open design, gate-level details, thru-hole or PLCC for easy hacking, well-established processors with existing tool chains, low-cost development tools for CPLDs, no FPGA, standard ITX case compatible, and so on. He quite reasonably decides to use more modern electronics for video (VGA), keyboard (PS/2), and program storage (flash drive). Along the way, he chooses to put three processors on the board instead of one:
- Zilog Z84C0010 (Z80)
- WDC W65C0256 (6502)
- AVR ATMEGA328 (RISC Controller)
When coming up with the concept and requirements, [Bernardo] had a fictitious alternate history in mind — one where there were follow-ups to the ZX80, PET/CBM, or TRS-80 from the late 1970s that were extensions to the original systems. But he also wanted a clean design, without cost-cutting gimmicks, in order to make it easier for learners to focus on computing itself — a didactic architecture, as he describes it. Turn the crank for seven long months, and we have the Cerberus 2080. [Bernardo] has put the design on GitHub, and made a video series out of the whole process, of which the introduction video is below the break. There’s even an online emulator developed by retro hacker [Andy Toone].
We wrote about the 6502-based ERIC-1 project back in 2014 which shared the bus with an ATMEGA simulating ROM. The Minty Z80 project from 2019 also uses a similar technique. Thanks to [Frédéric] for sending us the tip.