I'm working on a toy OS/kernel/what have you for my raspberry pi.
This is mainly as an educational experience; I don't have much experience with systems programming, or doing stuff without fancy nice userspace functionality like malloc.
Probably not particularly /useful/, but the code might be of interest to someone.
The serial implementation runs on UART0, which requires a USB-serial-debug-shenanigans cable for the raspberry pi, like the one here: http://www.adafruit.com/products/954