I'm interested in conducting extensive research on redesigning the input/output facility (not sure of technical terms). Harmed with google and a desire to become useful as a programmer, what are some of the topics I would be looking into or questions I need to be asking?

Of course I can grab a few open source implementations (printf, iosream, etc) and compare notes on the various implementations. Prior to doing this however, I'd like to know the theory behind it (what were the tools available to the designers of these libraries?). Basically I'd like to know how to write a single character to the screen or to a file if I had no printf(), or how how to get a single character from the keyboard if I had no scanf().

TIA,
Andrew