I first heard about it in 5th grade from a classmate, Tyler, whose older brothers played it. Then the next year, my friend Rob got a copy of the Holmes box. We poured over it on the bus rides to and from school. He had learned about it via the local Boy Scouts. That summer (1981), he ran me through my first adventure and I was hooked but we didn't have much time to play. The next summer (1982), I was drafted into DMing because yet another friend, Mike, got the first red box D&D. I DMed out of his copy, learning as I went.
At that point, we still thought the Moldvay red box fed into AD&D so I saved up some money and bought the AD&D Players Handbook at an outing to the nearest mall that had Waldenbooks. It was months later before I was able to get my hands on the DMG, so whenever I got to the mall, I read the DMG and took from the combat tables to use as our characters leveled up past the info in Basic.
Sadly, my friend Rob unexpectedly passed away just a few of weeks ago. I have him to thank for a life of RPG fun.