Identification of an old machine

This is going to be rather difficult I think. In 1977 when I first went to high school, we had a visiting computer science teacher (the school didn't own it's own computer). He used to come in with a PET mostly, but one day he couldn't bring the PET so came in with this old machine which was roughly cubic, each side about 2 foot. On the front it had a wiring panel where you had to plug in patch leads, and a rotary dial like on old telephones which was used to dial the numbers in. I don't remember how it displayed its results. Being a first year student and never faced with a computer before I had no idea what to do with it, and so don't remember much about it. However, now I'm intrigued - what was that beast? Does anyone have any ideas? cheers, paul