In 1978, I wrote a SNOBOL program for my MSc thesis. (SNOBOL is a dynamic, garbage-collected, string-oriented language, with bizarre syntax and control structures.) It needed a lot of memory (for the time). I managed to get an account on my school's IBM mainframe with a high enough balance to run this program a few times. But only if I did my run at 3AM. I forget if the total memory of the computer was 4MB, or that was the amount I was permitted to use, but yeah, 4MB.