The first computer I programmed was a GE mainframe on the GEISD network. I don't remember the particular model and I never got closer to it than the acoustic coupler on our school's Friden Flexowriter.

I also learned on ADP (Automated Data Processing as opposed to EDP Electronic Data Processing) equipment. My high school had an IBM 402 Accounting Machine, 082 Sorter, 087 Collator, and 029 Keypunch (I'm sure on the 402, the other model numbers I may be off on). For the youngsters here (which probably include just about everybody) you program most of these machines by plugging what look like big (1/4") headphone jacks on either end of a single wire into a big board with a bunch of holes. If you want to add up the first six columns of a deck of punched cards, you essentially plugged six of these from the input holes to the accumulator holes and then six more (or seven, you had to account for overflow yourself) from the accumulator holes to the output holes.

My last year of high school, I got to work on the school system's IBM 1401 which was a real computer with a whole freaking kilobyte of memory to work with. If your program was bigger than 1KB, you had to write it so that it would swap in and out in 1KB chunks. You programmed it in Autocoder which was a very small step up from assembler language.

In college I learned Fortran, COBOL, and ALGOL on a Burroughs mainframe. I also learned IBM 360 Assembler which ran on the Burroughs via an IBM 360 emulator. That and IBM 360 machine language so you could read a core dump (essentially a hundred plus page blue screen of death).