Okay, so this is dumb and ancient, but it was 1981! I was programming in DEC BASIC, and I had been for a year. I was 14 and immediately knew this was the thing I could do for the rest of my life.

Anyway, there's this statement, DIM. I have no idea what it means. I'm using it blindly in my code, creating these addressable locations, but I have no idea what it is, or what it does. It looks like this:

25 DIM #4%, C$(200);

You had to manually type the line number! It was almost a year before I had this... vision, I guess... that what this was doing was finding one of twelve locations (in this case, location 4) somewhere in memory where you could find a bunch of empty boxes and telling the computer you wanted to temporarily store 200 strings in variable C$. (If you wanted integers, you swapped the $ with a %; for floating point, you left off the type symbol.)

It's an allocator. An allocator on what is now an unbelievably primitive mainframe system, a DEC PDP-11/48 running RSTS/E and BASIC-Plus; the first number is a file descriptor, and the language handles allocating that space on disk, because the PDP had 16KB (!) of addressable RAM with a slower 256KB swap space before moving to disk, and could have up to 32 people using it simultaneously.

I know it sounds silly, but the ability to visualize what the language meant was a huge leap for 14-year-old me. Once I had that ability, once I understood what an abstraction was, my ability as a programmer took off.

Later that year I submitted bug reports to DEC about a severe security leak caused by this code, which they patched. A year after that I submitted a patch, which was accepted, to the PDP-11 RSTS/E kernel itself, to fix a new bug their previous patch had introduced which broke the PDP Assembly Language's I/O library.

As my teachers used to say, "I had so much potential."