Obtain Real-to-Protected Mode Switch Entry Point [0.9]

This function can be called in real mode only to test for the presence of a DPMI host, and to obtain an address of a mode switch routine that can be called to begin execution in protected mode.

Call With

AX = 1687h
Returns

If function successful
AX = 0
BX = flags

BitSignificance
00 = 32-bit programs are not supported
1 = 32-bit programs are supported
1-15not used
CL = processor type
ValueSignificance
02H80286
03H80386
04H80486
05H-FFHReserved for future Intel processors
DH = DPMI major version as a decimal number (represented in binary)
DL = DPMI minor version as a decimal number (represented in binary)
SI = number of paragraphs required for DPMI host private data (may be 0)
ES:DI = segment:offset of procedure to call to enter protected mode

if function unsuccessful (no DPMI host present)
AX = nonzero

Notes