Off the top of my head, I'd have to say Gödel, Escher, Bach: an Eternal Golden Braid. (aka GEB) I was in my mid/late-20's and always interested in math and comp

Off the top of my head, I'd have to say Gödel, Escher, Bach: an Eternal Golden Braid. (aka GEB) I was in my mid/late-20's and always interested in math and computers but pretty much low-level applied things. I read that book over the holidays cover-to-cover having my mind blown chapter after chapter. It was a page-turner. And I'm sure if I were to read it all over, I would rediscover it as well as getting into more depth and appreciating some of the other story/topic threads that I was less interested in at the time. The real answer though is my first computer, an Atari 400 8-bit machine--though I think I got it way before Christmas. I had been bugging my parents about a home computer all summer, first it was the Sinclair ZX-81 then maybe the TI-99/4a. These were all very expensive for a kid, so I declared it as my xmas/birthday and whatever presents all rolled into one, but I wanted it now. The VIC-20 was garbage and between the C64 and Atari, well I wanted to make video games and Atari was synonymous with that. To keep price down, I got the computer with Basic and Asteroids cartridges--so storage of any kind. I learned to code in basic and assembly (actually the machine codes as I had no assembler software I could load, so it was decimal numbers or strings poked into ram from basic). With no storage, I'd admire a program I spent days making for a while then power-cycle so I could play asteroids. I'm glad I skipped the cassette storage and got the floppy drive next year, which was like getting an HDD at that time for me. I learned things on that little machine that I still have vivid memories of and relate to in my thought processes solving problems.