He had access to timeshare IBM mainframes. So did I, at the same time. (He & I are the same age.) There were no homebrew or minicomputers. Both of us spent many hours programming, but even by the standards of a 1960s computer geek, he was extraordinary.
I'm about decade older than you or Gates, and had access to IBM 1600 then 360 mainframes at U of Oregon mid to late 60s. You two may have had great privilege working with mainframes when you were teens. There were likely hundreds of such teens, usually in cities or towns with mainframe infrastructure, often associated with universities. I did room and study in Palo Alto with geeks, some of whom were building definite "homebrew" systems of comparatively immense power, but that was the mid 70s. The DEC PDP series begins "minicomputer" evolution in ~1960.
As an aside: In Palo Alto in 1977, there were rumors of the "smartest person we ever met", in retrospect it may have been Jobs himself.