Intel iAPX 86 User Manual page 232

Additional Information for iRMX 86 Users
iAPX 86,88 Family Utilities
1-6
Example 3: Linking and Locating Programs with Overlays
Using OVERLAY Control
The easiest way to build an 8086 program that contains overlays is with LINK86's
OVERLAY control. Overlay modules built with this control reside in the same file
as the root. The operating system supplies routines that will load the overlays con-
structed in this way. See the
iRMX
86
Loader Reference Manual
or the
Run-Time
Support Manual for iAPX 86, 88 Applications.
After the program modules that will constitute the root and its overlays are
translated, each of the overlays and the root must be linked separately. Then the
root and all of the overlays are linked together.
The example following shows the first step toward linking overlays-linking all of
the modules that will constitute each overlay and the root separately:
*
LINK86 OV3.0BJ, OV3A.OBJ OVERL
LINK86 OV4.0BJ, OV4A.OBJ OVERL
LINK86 ROOT.OBJ, ROOTA.OBJ, RO
URXSML.LIB OVERLAY(ROOT)<cr>
Y(OVERLAY3)<cr>
Y(OVERLAY4)<cr>
TB.OBJ, &<cr>
Notice that all of the modules, including the root, are linked with the OVERLAY
and NOBIND controls. The overlay name for the root is not as critical as for the
overlays, since the overlay name is used when calling the loader.
Finally, the overlays and root must be linked together. Since anyone of the files
could be the root, LINK86 requires for the final link the file containing the root
must be first in the input list. During this final link, the OVERLAY control is not
used:
NK, OV3.LNK, &<cr>
*
In the invocation, the BIND control is specified. The resulting object file is exe-
cutable on an iRMX 86-based system.
Figure J-2 shows the LINK86 print file listing for the previous invocation.
There is nothing special about the invQcation line to LOC86 when locating a file that
contains overlays or that has been bound:
The RESERVE control prevents LOC86 from assigning memory addresses reserved
for the Operating System. However, the values you enter with the RESERVE con-
trol must depend on the size and location of your Operating System and other
application software. Figure J-3 illustrates the printout from this invocation.