There's nothing too terribly special about low level wizardry, other than you really _do_ need to understand how the hardware works, and how your language works. Oddball skills you really need to know (and can easily pick up if you have a mind to) include: a) Reading processor/part data books. These are your API docs. Most of your answers are in there if you care to look. b) Reading schematics. You don't need to be able to write/design hardware, but you need to be able to figure out what each CPU pin is wired to and how you're expected to access peripherals. Again, not hard to figure out if you put your mind to it. Very handy to know: How to use a multimeter/oscilloscope/JTAG programmer/logic analyzer. There are your debuggers. You don't need them often, but when you need them, you NEED them.