Emu.os -

If you want to truly understand what happens between pressing the power button and your first user program running, studying a minimal kernel like emu.os is one of the most effective ways. It strips away all complexity, leaving only the essential ideas of operating system design.

emu.os automatically captures lightweight, incremental snapshots of the entire system state (CPU registers, RAM, hardware I/O) at every instruction or designated interval. Because it is an emulated environment, this process is non-intrusive and does not alter the timing of the "guest" software. emu.os