Int 31 Fn FF00  P - Causeway - "info" - Get System Selectors/flags         [E]

   AX = FF00h

Return: AX = selector for flag address space (base 00000000h, limit 4GB)
   BX = selector for current PSP segment (limit 0100h)
   (E)CX = size of DOS transfer buffer (max 64K)
   DX = real-mode segment address of DOS transfer buffer
   ES:(E)SI = protected-mode address of DOS transfer buffer
   EDI = system flags (see #2833)
Program: CauseWay is a 386 DOS extender by Michael Devore and John Wildsmith
     for use with Watcom C++ or assembly language programs

Notes: the entire transfer buffer can be addressed with a 16-bit offset in
     protected mode
   CauseWay always maps selector 0040h to the BIOS data segment at
     real-mode segment 0040h; when not running under a DPMI host, CauseWay
     also provides selectors A000h, B000h, and B800h mapped to video
     memory

See Also: AX=FF25h

Bitfields for CauseWay system flags:
Bit(s) Description (Table 2833)
 0 32-bit code
 1 virtual memory manage enabled
 3-2   mode: 00 raw extended memory, 01 VCPI, 10 DPMI
 4 DPMI available
 5 VCPI available
 6 no memory managers
 7 application descriptor table type: 0 = GDT, 1 = LDT
 14-8  reserved
 15    debugging engine present