When I got started in computers, you had to do low-level bit twiddling to get anything very interesting done, so you pretty much couldn’t avoid learning about XOR. But these days, to a high-level programmer, it’s much more of an optional thing, and you can perfectly well not know much about it.

So I collected some thoughts together and gave a lecture on XOR. Slightly to my own surprise, I was able to spend a full hour talking about it – and then over the course of the next couple of weeks I remembered several other things I could usefully have mentioned.

All of it is available on this page.