There are some "door framework" packages out there. My assumption is that they come with some of the comm port handling, etc., already built in and you just have to program your door, but I don't know that.
That is the case, you're meant to be able to hand off all the comms operation to the external functions. Despite using TP 4 and 5, I never had any joy
with any of those setups, there were two main ones, but I can't recall the names now. Which is how I came to write the character send/receive having to play with registers and inline ASM.
Spec
*** THE READER V4.50 [freeware]
--- SuperBBS v1.17-3 (Eval)
* Origin: A camel is a horse designed by a committee. (21:3/101)