At 3, Jacob knew his alphabet and could find keys on the keyboard. He learned enough to remember, by rote or otherwise, that "worm" launched the worm game and "sl" launched steam locomotives, sometimes using a cheat sheet for help. He could not read or comprehend responses very well. (He derived a LOT of enjoyment from typing nonsense commands, then having me read the error messages that started with BASH)

At 5, he reads well. He is not good at spelling - one reason I give him a short cheat sheet - but he can make out a lot of what's going on. Not everything, of course.

We didn't start them on computers from the cradle. We read books to them a lot, and play games involving numbers and words. Jacob loves Dr. Seuss books and word games.

But lest anyone think we're some sort of tiger parents, we also open the front door and let them go play outside, maybe sending some sidewalk chalk with them if they want it.

I got a TRS-80 at about 5. It had only a CLI (BASIC-based). That was a huge incentive for me to learn to read. Nobody else in the house knew about computers then either, so unless I wanted to wait for my dad to get home from work, it was me and the manual.