I am old school. Back in my day computers didn't have screens. THey had teletypewriters... or a single line LCD! Ahem. First computer I worked on was a MITS Altair 8800. Yeah. I went there.
The first "computer" I bought was technically a calculator, but you could do a lot of programming with it. And I did. Nerd cred. The HP-41c, back when HP knew how to make good products.
My first "real" computer was the Kaypro II, a Z-80 based SUPER computer with a real color (all green) screen and two, count them two, single sided floppy disks and a whopping 64K of RAM. Smokin.
Sure, I did use a slide rule before that, and my hands before that. I even used an abacus, go figure. But, those are really mechanical aides not electronic computers. So, I'll stick with above list. I think this list makes me old...