I’ve bought a Brunsviga 18RK mechanical calculating machine, since it is a piece of computing history. Here it is:
It is awesome and I can report that everything seems to work. It can’t do negative numbers, so I have enjoyed doing things like entering 100 and then subtracting 150 to get a result of 9999999999950. That’s called underflowing the accumulator, and a bell rings when you do it.
In its honour, I have also written this C program:
int main(int argc, char *argv)
unsigned char test='A';
…which underflows an unsigned char, subtracting 66 from 65 to get a result of 255. For the sake of completeness I’m printing ACSII code 7 at the same time, so that a bell also sounds. I’m sorry.