I was chatting to a colleague recently and I asked what his understanding of the XOR operator was. He said that he had heard “XOR” being mentioned, but he admitted to having no clue as to what it was. I didn’t find this particularly strange as this is not something that I remember being taught during my studies. My own foundational primer on the topic from my dad while I was growing up.
My dad worked at Digital Equipment Corporation (which became Compaq and later HP) and he believed (…and probably still does) that VMS was the most powerful operating system ever developed. He came from the time when hard drives were removed from disk enclosures and were physically lubricated with oil (at least this is what he tells me, citation needed). He carried around with him, books that described how the machines worked, to a level of detail not commonly seen today. Back then, as big as they were, computers and the processes in place to repair them were thorough and concise, yet, still very elegant (in a nostalgic manner) despite the complexity involved.
The advantage of his experiences for me, was that I got to learn Boolean logic and the operating principles of simple gates. Some of my holidays as a child were spent building kit circuit boards out of 555 timers and decade counters (of which I’ve forgotten the model number) and completing truth tables, mostly by choice. One of my biggest dreams (I was ten) was to build a radio transmitter so that I could hear my voice on the radio (It didn’t occur to me then that I could call in to a radio station, but I suppose this would be different).
The lessons started off with binary, basically how computer systems work in zeroes and ones. This was followed by a lesson in the base 2 numbering system and how it differs from base 10. (I recall having read something explaining that if humans had, say 12 fingers instead of ten, we would probably have used a base 12 numbering system as the default.) Dad threw in some base 16 for HEX purposes and for my edification as well as base 8, just so that I can add something I’d never use to a already rapidly growing list.
Numbering systems all figured out , he moved me onto the AND logic gate and it’s theory of operation. In the next post, I will try to explain the gates and their boolean operations as I remember them. I hope that you will find this useful or interesting and enjoy with me my little trip down memory lane.