Initty searches for the environment variable BASECHO. If this variable is located and has a non-null value, this function simply returns zero. Otherwise, this function returns one after performing several tasks. First, this function gets the state of the tty associated with file descriptor fd and stores this information in tty. If fd is zero, ttyerase, ttykill and ospeed are set. In support of several BASIC I/O functions, initty also modifies the ttyís state to avoid most of the processing normally performed by the UNIX tty driver. Specifically, character echoing, the collection of characters into lines, erase and kill character processing and tab and newline processing are turned off.
Exitty sets the state of the tty associated with file descriptor fd to tty and returns zero.
These functions support tty initialization and wrap-up and do not directly implement any BASIC functions.
from The Basmark QuickBASIC Programmerís Manual by Lawrence Leinweber