I was a programmer, not a sysadmin, though sometimes I was in small shops where everybody kinda did sysadmin. My first experience was in college in the mid 60s with a PDP-8 but I didn't really get serious for another 10 years. But, it was a good time to be in computing. There were lots of different companies trying out different things, and you weren't forced into specializations. I worked for small companies, big companies, scientific companies with PhD physicists and chemists running around, business companies in one place working on transaction software for things like a supermarket checkout line and in another on stock trading software, and software development companies writing parsers with Lex and Yacc. Sometimes, working on unix systems, I'd just grab the manual and leaf through the whole thing looking for functions to do what I was trying to do. Now there's all this specialization with vast APIs to learn! I feel lucky I was in the field when I was.