...I once wrote a program to summon demons. It didn't work, mind. But I was really proud of my doubly-linked-list pentacle, each node of which contained a point

...I once wrote a program to summon demons. It didn't work, mind. But I was really proud of my doubly-linked-list pentacle, each node of which contained a pointer to the summoning point in the centre. I thought that was really elegant. Incidentally, if anyone is thinking of trying this for yourself: always remember to mlock() the memory containing your summoning. The last thing you want is some demon of the pit getting swapped out to disk. Not only is swap notoriously insecure, but sulphur buildup on the disk platter will cause a disk crash. And for heaven's sake, make sure your pentacle is properly aligned. If it's split across two pages, they may end up not being next to each other in physical ram, and then it won't work! Ideally, use an embedded device where you know what every cycle does. Don't be put off by the low power. You'd be surprised how much evil you can do with an Arduino.