(7) Lots and lots of programming. Ideally the tricorder should talk to the person, and listen to their answers, including such things as, "what seems to be the problem?" to get symptoms that it can look up.
Wouldn't "Please state the nature of the medical emergency" be more apropos?
"Now this is a totally brain damaged algorithm. Gag me with a smurfette." -- P. Buhr, Computer Science 354