The MFD-0816 (alternatively MFD0816, mfd0816 (because im not a very consistent
person)) is a 16-bit fantasy CPU and based on the intel 8088, it features a
word size of 16 bits, a 16 bit address bus, 4 16-bit general purpose registers
and a general purpose I/O bus with support for block I/O.

The current versions of the design/specification alongside the preliminary
instruction set reference are available here.
The implementations of both an assembler and emulator are now
publicly available on GitHub under the GPLv3. Note that the assembler is in a
"beta" phase whilst the emulator is still unfinished, missing some instructions
a way for user interaction and serious testing for correctness.

All documents detailing the design of the MFD-0816 and other fantasy hardware
and tooling around it are licensed under the CC BY-SA 4.0 license.