Comment by watersb

This 32-bit microcontroller has 1 kB of RAM.

The Apple Disk II Controller discussed yesterday used two 256-byte ROM chips and a shift register for dynamic memory.

https://news.ycombinator.com/item?id=48723102

The linked article of the Disk II Controller has great detail about the state machine encoded in one of the ROMs, and walks through the bootstrap code stored in the other one.

I haven't tried any microcontroller projects myself, but my first computer projects were on the small home micros of the early 1980s. I enjoy this kind of thinking.