INT 21 - Novell NetWare - MESSAGE SERVICES - SEND BROADCAST MESSAGE
AH = E1h subfn 00h
DS:SI -> request buffer (see below)
ES:DI -> reply buffer (see below)
Return: AL = status
00h successful
FEh I/O error or out of dynamic workspace
Note:   this function is supported by NetWare 4.0+ and Advanced NetWare 1.0+
SeeAlso: AH=DEh/DL=04h,AH=E1h/SF=01h,AH=E1h/SF=04h

Format of request buffer:
Offset  Size    Description
00h    WORD    length of following data (max 9Eh)
02h    BYTE    00h (subfunction "Send Broadcast Message")
03h    BYTE    number of connections (01h-64h)
04h  N BYTEs   list of connections to receive broadcast message
BYTE    length of message (01h-37h)
N BYTEs   broadcast message (no control characters or characters > 7Eh)

Format of reply buffer:
Offset  Size    Description
00h    WORD    (call) size of following results buffer (max 65h)
02h    BYTE    number of connections
03h  N BYTEs   list of per-connection results
00h successful
FCh message rejected due to lack of buffer space
FDh invalid connection number
FFh blocked (see also AH=E1h/SF=02h)

See also: 21DE

21E1 - Novell NetWare - MESSAGE SERVICES - SEND BROADCAST MESSAGE