Int 21 Fn FF80  - Topware Network OS V5.10+ - Send Message                 [N]

   AX = FF80h
   DH = FFh
   DL = destination address (FFh for broadcast)
   CX = message length (max 2000)
   DS:SI -> message to be sent (see below)

Return: nothing
Program: TopWare Network Operating System is manufactured by Grand Computer
     Company

Notes: this function is supported on both Workstations and the server
   there is no guarantee that the message will be received correctly, or
     at all, by the destination

Format of message:
Offset Size    Description
 00h   BYTE    type code
       07h TopSend
       11h user application
       other reserved for TopWare
 01h   var data

Note:  sending messages with a type code other than 11h will cause
     unpredictable results