The Sorbus Computer

The Sorbus Computer is a small, cheap, and expandable computer based upon the 6502 or rather the 65C02 CPU and an RP2040 microcontroller from Raspberry Pi. It is fully open source, the source code is available at GitHub.

The means that even the hardware is for the most part software written in C. The kernel for the 65C02 is written using the ca65 assembler from the cc65 cross-compiler suite.

While the original implementation of the machine was distributed among three PCBs, the current iteration (called the Junior) has merged those three boards into a single one.

What can it be used for?

It's good for a couple of things. Even more than I expected, when I first built this machine. Here are a few suggestions:

Understanding The 6502 Processor Family

There is a course devided into a couple of sessions that takes a dive into understanding how the CPU works by looking at what happens on the bus during each clock cycle. For this a tailored firmware (core) called MCP has been written.

Running The Replica Of An Apple 1 Computer

Ever wanted to know, how you would have worked with an Apple 1? Here is how you can try this out. It's more cumbersome that you'd probably think.

Implement Your Own Design Of An 8-Bit Computer

A lot of example code is already available. And this is more fun, than you'd probably think. I know, because I did this

Running The Sorbus JAM Core To Have A Capable 8-Bit Computer

The Sorbus JAM is the core designed especially for this hardware. It includes a 4MB mass storage device utilizing the flash of the RP2040 board. Ir's capable of running CP/M 65, TaliForth2, Microsoft BASIC 1.0, several machine language monitors, and a couple of other things.

It can also run demos as you can see here: 1k LEDs Is No Limit.

Why The Name "Sorbus"?

I liked following the tradition to name it after a fruit. Think about it: it uses a Raspberry (Pi) and can run like an Apple (1). However most fruits were already "taken". So, then I remembered the German "Vogelbeeren" that were around in my childhood. My mother always told me: "Do not eat those, they are poisonous!" She was a bit exaggerating there, as the "only" make you sick in the stomach, and don't cause and serious health issue you. However, I still played with them, throwing them around and other things that kids do.

So, this is a very fitting name for this computer: it's something you play with, but not for the "primary use" of a computer, like word processing. I looked up for a good translation and found Sorbus. Also, here is an image provided by Sir Garbagetruck.