[jecel]

The term hacker is indeed pretty old. As far as I know the MIT model train club divided themselves into the artists who worked on the scenery on top of the board and the hackers who worked on the underside of the board on the fancy electrical switching they had adapted (hacked) from telephone exchanges. When computers first arrived at MIT this latter group moved their focus to them and the term "hacker" moved with them into computing.

Other comments have mentioned "cracker" in relation to invading systems. Before computers we had "safe-crackers".