What you saw was the cold start procedure for a completely uninitialized machine -- manually enter a short bootstrap loader of a dozen instructions or so, just enough to load a longer one from whatever I/O device was handy. A lot of machines had this kind of start procedure -- if there's a large row of switches on the front panel, that's probably what they were there for.

(Core memory would retain its contents without power, so if you were absolutely sure nothing could possibly have disturbed that initial bootstrap routine since the last time you toggled it in, it might still be there. But a lab minicomputer of that era, probably didn't have any memory protection at all, so that's a pretty big "if".)