MIT tech model railroad club definition - hacker:

In the 1960s, the MIT all-male computer geeks had an incurable curiosity about how things worked in the real world and in the cyber world. Back then, computers were huge mainframes stored in temperature-controlled, glassed-in lairs. These slow machines were expensive hunks of metal (called PDP) that allowed computer programmers only very limited access. Nevertheless, the Signals and Power committee of MIT’s Tech Model Railroad Club chose the PDP-6 and PDP-10s as their favorite “tech toy.” Because of the computer’s slow pace, the smarter programmers created what back then were called “hacks,” or creative programming tricks, to complete their jobs faster.