There was a time, not long ago, when new products were built on new ideas, and the marketplaces were very, very heterogeneous.

Now, the marketplaces are largely commoditized and new products are incremental improvements and extensions of previous ones. The old ideas and products are still there, fascinating history to be explored.

An example - on a new Linux system, look at the man page for "termcap", and you will find configuration data for the Teletype model 33 and the Lear Siegler ADM-3. That makes people like me go "Hmm!" in a fascinated tone of voice.

History is like dead reckoning navigation. We only understand where we are by knowing where we were and what was done to get from there to here, and there are those of us very interested in such things.

This is only a partial answer to your question.