I worked my way through college as a UNIX system administrator for the Engineering College of my school. This was back in the late eighties when disk and memory weren't dirt cheap, and we had to limit students to 1 Mb (thats 1 Megabyte) of disk space on the UNIX mainframe. Professors were lucky and got 2 whole Mb of disk space. Also, any program that ran, student or professor, had to run in 1 Mb of memory.
There was a professor that had approached the other sys admins one by one with the same problem and received no satisfaction. One day my turn came. His complaint was always the same, "My program won't run".
We had already investigated this and we knew exactly why his program didn't run: "That's because it uses more than 1 meg of memory," I told him.
"But I have 2 Meg of memory," he said.
"No, that's how much disk space you have."
A blank stare. "My program only takes 1.5 meg to run"
"You only get 1 meg of memory."
"I'm a professor, I get two megabytes."
"No, that's how much disk space you get. Everyone gets 1 meg of memory."
"I get two megabytes."
And so on, and so on. He simply didn't understand the difference between disk and memory space. And he was a professor of Engineering.