It was an incredible time to live through as a young kid. There was a Cambrian explosion of computer designs - new systems coming out every month, each outdoing the previous ones. I remember rushing to the store each month to buy and devour the latest computer magazines. Felt like a time of endless possibilities. Only downside was I couldn't afford any of it except for a ZX81 (which was great in its own way).
My grandfather worked for Sperry and we had circuit boards from Univacs in our basement when I was young. Then I bought an Atari 400 and B&W TV for the display when I was 11. Looking back it was pretty neat getting to see what came before, down in my basement. I don't think I ever had a tape drive for the Atari. I met some kids that had C64s (and modems) and that lured me over to the C64. The documentation for the C64 was so much better than anything I had for the Atari. I had BASIC for the Atari, but that was it. The C64 manual I had included assembly language programming, and the full schematics for the computer, so I was really able to learn everything about the system and explore all of it. It was so much fun.
And as a teen- going from making a MASH game using graphics characters on a trash-80 to color characters on a vic and getting my own PC for the first time, C64, and discovering sprites..