The first computer I worked on had a 32k hard drive. Yes, 32k! It was in a 19" rack and was about 7" high. This was about 1974.
One of my computer professors in college talked about working on a machine with no RAM at all--there were only ALU registers (16 I think), and a drum (precursor to a disk). Part of the instruction field was the address of the next instruction on the drum; they manually computed how far the drum would turn while an instruction was executing, then tried to figure out how to optimize the program--you didn't want to have to wait for the drum to make another complete rotation to be able to execute the next instruction! I believe that this was in the late 1950s to early 1960s.