It's not bound to any host OS. I am using SDL to provided a simple abstraction to open a Window and obtain key and mouse input. I use very little of the SDL features, just a rectangle fill and rectangle bit blit. See the gui/ctx/class.inc for all those, everything else in the GUI, like the compositor and vector graphics library, widgets et al are done in VP on the CrysaLisp side.

I have a small abstraction to the host OS via the sys/pii/functions, these just use the jump table you can see in the main.c file. Any host OS should be able to compile the main.c with little or no changes, but eventually there will be a native filesystem available from VP/Lisp.

I will be doing direct bare metal hardware support, and there are things happening on that front but I can't talk about that here.

But during my experimentation stage it was very useful to have it running hosted, and I'll keep the hosted version running going forward as it provides a nice dev environment.

I do have a plan to get a version done that could boot under VMWare etc, but I've only got so much time on my hands and have to spread myself over the whole codebase as best I can. :)