INT FD - TFPCX - INSTALLATION CHECK AH = function (also see separate entries below) Program: TFPCX is an interface between modem and terminal program for packet- radio communications InstallCheck: test for the string "N5NX" three bytes beyond the interrupt handler Range: INT FD is the default, but may be changed, so the full installation check consists of scanning for the signature Note: TFPCX returns AX=FFFFh on any unsupported function call SeeAlso: AH=01h,AH=03h,AH=FEh