This is my daily driver, a 1992 Trek 820 in electric blue with black spatter. I got it for free from my brother about a year ago, and have since put ~4K miles on it. I have another 820, and I love these bikes. They make great city bikes. They're dirt cheap, geared well for the hills in my area, and they just work. It's nice to have something in your life that you don't ever have to even think about. I've made some upgrades for my use, including the racks, basket (I have a second I attach to the front rack for Costco runs), fenders, street tires, and high rise handlebars.
Exactly. It was their entry level model to compete with the Specialized Rockhopper and similar bikes. Back in that era I had a Diamondback Ascent, a similar entry level MTB, that I rode on trails with friends.
IIRC, the Specialized Rockhopper was mid-range. Hard Rock was their entry level.