Intel iAPX 86 User Manual page 256

iAPX 86,88 Family Utilities
Additional Information for Intellec Series IV Users
Example 6: Linking and Locating Programs with Overlays
Without OVERLAY Control
It is harder to produce overlay modules wilthout using the OVERLAY control.
However, sometimes it is necessary to build programs in this way, for example, for
running under an operating system that does not support overlay modules contained
in the same file as the root module.
But regardless of the reason, building overlays in this fashion places an extra burden
on the programmer. He must do some of the work that would be left to LINK86
(and LOC86) if he were to use the OVERLAY control. In the following example we
prepare a root and two overlay modules in separate files.
First we must compile all modules. Examplies of the invocation lines are shown
below:
>
PLM86 ROOT.SRC S,ALL<cr>
>
PLM86 OV1. ,RC SMALL<cr>
>
PLM86 OV2. RC
SM~LL<cr>
The next step is to link the root module to resolve external symbols with a library
and to obtain a link map:
>
LINK86 ROO .OBJ, USER. LIB MAP<cr>
We will need the link map for locating purpos,es. The link map, shown in figure K-6,
shows the size of each segment in the root. Since the overlays are self-contained except
for references to the root, we do not need a link map for them. The PL/M-86 listing
files will show the size of each overlay's segmt:nts, as illustrated in figure K-7.
iNDX
~O~6
LINKER,
V~y
INPUT FILES: ROOT.OBJ ,USER.LIB
OUTPUT FILE: ROOT. LNK
CONTROLS SPECIFIED IN INVOCATION COMMAND:
MAP
DATE:
MMIDDIYY
TIME:
HH:MM:SS
LINK MAP OF MODULE LOANER
LOGICAL SEGMENTS INCLUDED:
LENGTH ADDRESS ALIGN SEGMENT
BA9BH ------ W CODE
0381H ------ W CONST
0291H ------ W DATA
0030H ------
w
STACK
OOOOH ------
w
MEMORY
INfUT MODULES INCLUDED:
ROOT.OBJ(ROOT)
USER.LIB(LOADER)
USER.LIB(~XIT)
USER.LIB(ERROR)
USER.LIB(TIME)
CLASS
CODE
CONST
DATA
STACK
MEMORY
OVERLAY
Figure K-6. LINK86 Map for Root File
-
K-ll