This is a telegraph! - today's generations don't know what telegraph means, they only know like, lol, brb, sms, text.. please text me.. I texted you.. When my father sent me to the post office to send a telegraph, he counted the words and calculated the cost.. because post office charged by the word... amazing all this technological achievements happened in one's life.
So true. Technology is what has most changed, but the underlying principles remain similar: You have something to say/transmit. It is translated/coded with some mutually agreed dictionary, which, in some cases, is fixed, and in other cases goes along with the message (but once again there are rules that allow the receiver to understand at least this part and then proceed with the rest). In some cases then it is compressed and finally scrambled. Then translated to the physical layer (1's and 0's or "." and "-" converted to electrical pulses, light, logical levels, with or without clock, or modulated, each symbol corresponding to one or more bits). The receiver implements the same logic but from bottom to top.
ISO's OSI levels describe how these different layers work and how they are related to each other, and many implementations are based on it. I think this is a key piece.
That is why nowadays it seems "so easy" (ehem), to integrate new standards to our daily life (for instance, a new RF modulation scheme) as soon as they appear:
- The end-user doesn't even notice it (just can enable or disable that peripheral).
- The programmer gets the API with the related Subs and events, and works with it as with any other " transmission channel".
- The embedded developer just has access to some registers which give access to low-level information and implements the API for the above
- The chip manufacturer offers some registers which allow the developer to customize and control its behaviour
Of course there are many more details and intermediate layers involved, but it is nice to see the whole image of it.
