I'd say handling interrupts, paging/the memory subsystem, filesystems and scheduling were all pretty worthwhile. It's important mostly not to worry about the f

I'd say handling interrupts, paging/the memory subsystem, filesystems and scheduling were all pretty worthwhile. It's important mostly not to worry about the finer details/getting things perfect - you almost certainly won't be able to make anything which is practically useful but it's an awesome learning experience :) One thing that is very helpful to stop you from tearing your hair out is getting hold of a function to do sprintf() early on - it's no fun to write, just messy, and it lets you do primitive debugging. This seems like a good shot, despite the sketchy looking URL: http://read.pudn.com/downloads97/sourcecode/unix_linux/396444/%E5%A4%8D%E4%BB%B6%20%E5%88%9B%E9%80%A0%E4%BD%A0%E8%87%AA%E5%B7%B1%E7%9A%84%E6%93%8D%E4%BD%9C%E7%B3%BB%E7%BB%9F/example/%E7%AC%AC11%E7%AB%A0%20%E7%B3%BB%E7%BB%9F%E8%B0%83%E7%94%A8%E5%AE%9E%E7%8E%B0/doprintf.c__.htm http://read.pudn.com/downloads97/sourcecode/unix_linux/39644...