During the COVID lockdowns I revived an old hobby: fiddling with electronics. I discovered the YouTube channel of The 8-bit guy. and check out some videos of Ben Eater. From that first “Hello World” video, and playing with my old C64 and studying its great documentation, I slowly designed my own complete 8-bit computer.
I designed the whole thing from scratch, including:
- An assembler
- An eeprom programmer (both client software, firmware and hardware)
- A virtual machine
- The board itself of course
Of course, I only used open source software on my trustworthy Linux laptop:
- Python for most client-side programming (assembler, eeprom-programmer)
- C for the virtual machine (because I found a good 6502 emulator written in C)
- C++ for all Arduino firmware (eeprom-programmer, clock timing, monitoring)
- My own 6502 assembler dialect for the board’s software
- KiCAD to design the PCBs
- Visual Studio Code to do all coding in, with the PlatformIO plugin for the Arduino work
The board I have now is version 1.0 (it has a few bugs in it and missing some parts; who needs a clock circuit anyway, right?!), but current specs will probably not change much:
- 6502 processor, running 4 or 8 MHZ
- 32k RAM
- 32k ROM
- 2 parallel 8 bit input ports
- 2 parallel 8 bit output ports
- A display connector (this makes the output ports unusable)
All code can be found on my GitHub page.