This week’s puzzle is to copy the carry flag to the high bit of ah. You may destroy any other register, the flags, and the other 24 bits of eax. Shortest sequence wins.
Why does PUSHA also push the stack pointer?
This puzzle is actually a quite easy one – but when I asked it in a university course, it kept some people busy for some time to find out the answer, so I thought it might be a good idea to ask you nevertheless: