My one rule of robotics (and pointed sticks, cars, crackpipes and umbrellas) is this: my stuff ought to perform in accordance with my wishes.
There might be additional laws ("weld here and here, but nowhere else," or "use the rules in /etc/iptables/rules.v4" or "don't shoot at anyone whose IFF transponder returns the correct response") which vary by whatever the specific application is, but these rules aren't as important as The One above.
There are various corollaries that you can infer from the main law, but since they can be derived, they don't need to be laws themselves. (e.g. if my interests conflict with someone else's, then my robot and my umbrella ought to serve my interests at the expense of the other person's interests.)
With regard to harming other robots, that also can be derived. If I desire to kill a knight on a robot horse, then my robot ought to turn them into a pile of bloody gore and shredded circuitboards immediately. OTOH, if I don't desire to kill a robot, then my robot should not do things that incur unnecessary liabilities.