Int 5B  - Isolan Multi Protocol Software                                   [N]

   ES:BX -> Transfer Control Block

Return: AL = status

Note:  this software interface allows multiple protocols/software packages
     to access a BICC 411x network card

Format of Transfer Control Block:
Offset Type    Description
 00h   BYTE    command code
       B3h Status
       F2h Activate
       F3h Deactivate
       F4h Send Data
 01h   BYTE    command identity
 02h   BYTE    virtual circuit ID
 03h   WORD    buffer length
 05h   DWORD   buffer pointer
 09h   BYTE    expedited data flag
 0Ah   BYTE    cancelable flag
 0Bh 16 BYTEs  local network address
 1Bh 16 BYTEs  remote network address
 2Bh   DWORD   asynchronous notification routine
 30h   DWORD   local network number
 34h   DWORD   remote network number
 38h   BYTE    call timeout
 39h   BYTE    not used
 3Ah  8 BYTEs  reserved
 42h   BYTE    command code extension
 43h   WORD    Blue Book MAC type