The first computer I ever got a look at was an IBM 1130, safely esconced behind glass in the college's computing center. No student could touch it; you laid a deck of Hollerith cards on the counter, and if you were lucky, an hour or two later you'd get your deck and a printout back. Usually proclaiming that you had a syntax error on one of the cards (good luck figuring out which one).
I was sitting with friends one day musing about having a computer that we could actually sit down at, type in commands, and run programs without waiting for the batch jobs to run. One of the guys (who lived down the hall from me) said, "Oh, you don't know about Ben?". He pulled me aside and informed me that the school had an old ex-military computer down in the basement in a locked room. But if you were a serious student and wanted to learn about computers, the school's EE department head would arrange for you to get a key to the room and after some instruction, leave you alone with the computer!
The computer? It was this:
https://en.wikipedia.org/wiki/Bendix_G-15(Yeah, the nerds called it "Ben" for short) It was all vacuum tube logic, and the memory was a rotating drum coated with multiple stripes of magnetic material. I/O was a Friden Flexowriter with relays and contacts wired under the keys so that the computer could use it for output as well as accepting user input.
To boot the thing, you had to set up the front panel to initialize the Flexowriter's I/O channel, then use it to type in a couple of octal commands that, when executed, copied the boot loader into memory from a punched paper tape. That allowed you to read the OS in from another paper tape. After that, any user programs you wanted could also be loaded from the tapes. If you were careful and paid attention, you could boot the machine up and have a program loaded in 10 minutes or so. We'd run a Blackjack game or its version of ELIZA, use the machine's utilities for running some calculations, and try to figure out how to write a program that didn't freeze the machine, requiring a power cycle. I hope it made it into a museum somewhere, because that computer certainly started a few serious programmers on their path to software development.
But that was the first computer I ever actually
used.