Itsy-OS Kernel: Premptive Switcher & Memory Manager
"Itsy-OS v0.1 is a small 8086 operating system kernel providing two basic services: a simple preemptive task switcher and memory management. If necessary, simple IPC and task management can be added to provide the features of a traditional microkernel. Weighing in at about 380 bytes, Itsy should port well to tiny architectures."