INT 60 - FTP Packet Driver 1.10+ - HIGH-PERF FUNC - ASYNCHRONOUS SEND PACKET
        AH = 0Ch
        ES:DI -> pointer to IOCB
Return: CF set on error
            DH = error code (see AX=01FFh)
        CF clear if successful
SeeAlso: AH=0Bh"Packet Driver"

Format of IOCB:
Offset  Size    Description
 00h    DWORD   pointer to buffer
 04h    WORD    length of buffer
 06h    BYTE    flags
                bit 0: packet driver is finished with IOCB
                bit 1: application requests upcall when driver completes
 07h    DWORD   function address for upcall
 0Bh  4 BYTEs   future gather write
 0Fh    BYTE    ???
 10h  8 BYTEs   private driver workspace

Completion function called with:
        ES:DI -> IOCB passed to INT 60/AH=0Ch