I'm reverse-engineering a small circuit board and there are several extremely low value resistors. A couple are 4.7 ohm and there is a 1.9 ohm and a 1 ohm as well. A couple of them are connected from a microprocessor pin to ground. What is the purpose of these low value resistors and aren't they essentially a short circuit? FYI, I know for a fact that they are resistors and not inductors.