Whats your late-80s/early-90s computer setup for your kids to mess with?

I grew up with a simple computer: It had some software and programming stuff on it and it wasn't connected to the internet. I was able to just mess around and learn how computers worked, how to use them, and the basics of how to program, without my parents worrying that I was 1) breaking something they needed for work or 2) finding 4chan.

What are your setups for your elementary-aged kids? Do you have a system they can just mess with and break and it's no big deal? Specifically if it's not just a regular hand-me-down computer, what is it and what's the setup?