I've released version 4.0 of MikeOS: http://mikeos.berlios.de
It's a 16-bit real mode operating system, written in assembly language, designed as a learning tool with detailed documentation. The big changes for this release are:
* BASIC interpreter with 24 instructions
* Text editor updates -- you can run BASIC code by pressing F8 (like a mini-IDE)
* If there's a file called AUTORUN.BIN or AUTORUN.BAS, the kernel executes it automatically on startup
A complete guide to the BASIC interpreter is here: http://mikeos.berlios.de/handbook-appdev-basic.html
See the end for some example programs. Also of note is that this release is confirmed to boot and run from USB keys -- see the User Handbook on the site for more information.
If you loved to code in BASIC during the classic 8-bit days, give it a go and send me your efforts -- I'd love to put more BASIC apps/games on the disk for the next release