INT 0C - IBM SYSTEM 36/38 WORKSTATION EMULATION - API POINTER
   Call offset 100h in the interrupt handler's segment with
        AH = function
            03h update screen
            05h select next session
                AL = session number (00h-03h)
                Return: AL = session type code
                            00h not active
                            01h display session
                            02h printer session
                            FEh invalid session number
                        DS = requested session's data segment (0 if not active)
Return: ???

Format of emulator's data area (offset from interrupt handler's segment):
Offset  Size    Description
13Eh    BYTE    bit flags for status line indicators turned on since this byte
                last zerod
13Fh    BYTE    bit flags for status line indicators turned off since this
                byte last set to FFh
140h    WORD    offset of EBCDIC to ASCII translation
146h    WORD    offset of EBCDIC screen buffer
148h    WORD    offset of EC (engineering change) level signature
150h    BYTE    "KEYI"
151h    BYTE    5250 key scan code to be sent to remote
15Bh    BYTE    "SYSAV"
15Dh    BYTE    5250 cursor column
15Eh    BYTE    5250 cursor row
167h    BYTE    "DVCTAD"
178h    BYTE    "FLAGS"
184h    BYTE    "SESSNOAD"
193h    BYTE    "STNAD"
198h    BYTE    "NSDS"