As a successor to my previous project[1], a Forth interpreter that runs under the TI operating system, I decided to go all the way and write my own assembler and OS. This is a project I've been working on for just over a month, but there's still a long way to go. The idea is to have a kernel + the Forth interpreter and compiler, then users can modify how their operating system works through the Forth files. My Forth implementation is mostly ANS-standard conforming, so most code should work right out of the box without any problem. See the GitHub repository for more, along with building instructions (you only need Guile and make build!)

[1] http://github.com/siraben/ti84-forth