INT 6B - NPC NCSI EXTENDED SERIAL I/O - READ DATA ON A VIRTUAL CIRCUIT AH = 19h AL = virtual circuit number CX = number of characters to read ES:BX -> buffer for received characters Return: CX = 0000h if failed CX = nonzero (possibly number of characters received) if successful Note: this function is also supported by TelAPI SeeAlso: AX=0100h,AH=12h,AH=18h