I’ve come up with a working definition of an operating system, that “An OS should provide everything needed to run a shell”. Its a bit all encompasing, but at least I can refine it now.
I had an interesting conversation with Bart at lunchtime about the semantic differences between using the traditional UNIX/Plan9 file interface for accessing global namespaces, and treating these namespaces as objects of type file. I’ve yet to come up with a conclusion, but it’s interesting.
Charles is building me a computer from a ZX80A, his favourite microprocessor. It’ll have a keypad for input, an LCD for output and a huge 32 kilobytes 
of RAM. Should be ready in two weeks. I need it to play around with the practical implementation of OS’es.