INT 21 - LAN Manager - TCPDRV.DOS - API AX = 4402h BX = file handle referencing device "TCPDRV$" CX = 0019h DS:DX -> buffer containing request block (see #01504) Return: CF clear if successful buffer filled CF set on error AX = error code (01h,05h,06h,0Dh) (see #01680 at AH=59h/BX=0000h) Program: TCPDRV.DOS is the low-level device driver supporting LAN Manager's TCP/IP protocol stack