(Adult Content: references to computers older than my high school diploma.)
Two dozen years ago, I moved into a house with an old-fashioned electric resistance furnace. Now, I cannot claim to never have lived in such a house before; after my dad's transfer to eastern PA we moved into an all-electric house, in the days before heat pumps. My parents still live in that house, though they are now on their second heat pump (FAR more efficient, as modern heat pumps tend to be) rather than the relatively inefficient electric resistance furnace that house started with.
However, I had never paid attention to my parents' utility bills while I lived there. Something about being in middle school and high school at the time.
Back to the early 1990s, we moved in during the spring and I didn't run the furnace before that autumn. (The air conditioner was separate and generated electric bills about the level I expected over the summer.) Then heating season came, and I totally gacked at the first electric bill after we turned on the heat. In a panic I called my dad and said "Is it normal for an electric furnace from the early 1970s to generate electric bills nearly double those when running the air conditioner in summer?" My dad, somewhat to my surprise, said "Yes -- that bill is not indicative of your furnace needing repair, they really do cost that much to run."
Holy crap.
The following spring, we were asked if we could do a friend a favor, and store one of his currently unused computers in our garage (which was effectively a storage unit at the time anyway). We said sure. Now the computer in question turned out to be a
Prime 650 supermini. When George rolled it in, I looked at it and said "How big is the power supply on that?"
George: "45 amps, 110 volts."
Me: "That sucker is about the same size as my piece-of-shit electric furnace, which also takes 45 amps. If I could convince the landlord to take it out and install your PR1ME in its place, then during heating season we'd have just as much heat *AND* lots of computing power, and I bet it would cost less to run than the furnace!"
20-something years later that idea has made it to the commercial marketplace:
Heating houses with 'nerd power' *facepalm*
(Footnote:
The History Of "Prime Computer, Inc." on a site run by a former employee.)