INT 15 - Rational Systems DOS/4GW - INITIALIZE PROTECTED-MODE INTERFACE
AX = BF05h
BX = PSP segment of extender
Return: nothing???
Notes:  if BX is not the PSP segment of the extender, it passes the call down
the INT 15 chain; this allows nested instances of the extender
calls INT 67/AX=DE01h if ???


15BF05 - Rational Systems DOS/4GW - INITIALIZE PROTECTED-MODE INTERFACE