The 256-Series is a series of computers of various sizes and architectures that I constructed. Currently most of them are still a work in progress. 

The Femto-5 (WIP):

A Von Neumann 20-bit computer, designed and optimised for CircuitVerse, with a planned microcode writer, assembler, and compiler. 

The Femto-4 (v2.6): 

https://circuitverse.org/users/4699/projects/femto-4v2-6-computer

A Von Neumann 16-bit computer, capable of running simple games, driving a 16x16 screen or a 32x32 screen, with an assembler, and a compiler for the Femto-4's high level language, Phemton Lite (a1.0). 

The Atto-2 (WIP): 

A Harvard 8-bit computer, capable of running simple graphics. 

The Zepto-1½ (WIP): 

An 8-bit register machine

The Zepto-1 (WIP): 

A 4-bit register machine. 

The Yocto-½ (v0.1): 

https://circuitverse.org/users/4699/projects/yocto-v0-1 

A Turing Machine. 

The Yocto-¼ (WIP): 

A true 2-bit computer. It's basically useless. 

The Ronto-¼ (WIP): 

A true 1-bit computer. It's entirely useless.

The name of all of the computers and the series as a whole is reference to the Pico-8.