INT 2F U - DOS 4.x internal - SET DOS VERSION NUMBER TO RETURN
AX = 122Fh
DX = DOS version number (0000h = return true DOS version)
Note:   not available under DR-DOS 5.0 or 6.0
SeeAlso: INT 21/AX=3306h

See also: 2130

2F122F - DOS 4.x internal - SET DOS VERSION NUMBER TO RETURN