The Beginner's Computer Handbook (1983)

I had this book too, as well as a more "general purpose" computing book explaining concepts. The Usborne series were excellent, and burned into my brain -- the Usborne book of knowledge, for example, I absolutely loved. The illustrations, as this example also shows, are fabulous and stick with me to this day (especially the one about sex!)

What was odd was that the computing book -- which I think my parents had picked up very cheaply in a charity shop -- kept on mentioning these devices like Mini computers and Mainframes and all sorts of fun, exciting things that were clearly very different to the boring old personal computer that I had access to with my dad. For a long time, I wondered when I'd be able to meet a real computer, barely aware of the exponential progress that had happened at an astounding rate since ~1980.