Except that this doesn't work on many systems. I don't remember the exact details, but neither on my old 386SX nor on my 486SX this worked to reboot the system. On one it just printed "NO ROM BASIC", and on the other it just locked up the machine.
The JMP FFFF:0000 trick worked everywhere
It is very impressive when it works, though :) as the entire self-test portion is skipped and the machine should go straight to "Starting MS-DOS..."
Devices will be left in whatever state they were a moment before, so yeah.
Put 1234 in 40:72 (E 40:72 34 12 in DEBUG) before the JMP FFFF:0000 to do a warm reboot, this will bypass the self-test portion.