INT 21 - Phar Lap 386/DOS-Extender - ISSUE REAL-MODE INTERRUPT
AX = 2511h
DS:EDX -> parameter block (see below)
Return: all segment registers unchanged
EDX unchanged
all other registers contain values set by the real-mode int handler
the flags are set as they were left by the real-mode interrupt handler
real-mode register values are returned in the parameter block
Note:   this function is also supported by FlashTek X-32VM
SeeAlso: AX=2505h,AX=250Eh,AH=E3h"OS/286",INT 31/AX=0300h

Format of parameter block:
Offset  Size    Description
00h    WORD    interrupt number
02h    WORD    real-mode DS value
04h    WORD    real-mode ES value
06h    WORD    real-mode FS value
08h    WORD    real-mode GS value
0Ah    DWORD   real-mode EAX value
0Eh    DWORD   real-mode EDX value
Note: all other real-mode values set from protected-mode registers

See also: 212503

212511 - Phar Lap 386/DOS-Extender - ISSUE REAL-MODE INTERRUPT