Computers made using vacuum tubes were so big they were the size of what?

Answer 1

A Bungalow

Answer 2

...entire houses. They usually filled one or more rooms, and were only able to handle very simplistic tasks.

Programming these monsters was done using punch cards. You punched holes in the card, which was one command to the computer to do something, then you inserted those cards one at a time through a feeder until the entire program was entered and running. You then waited for the results.