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APPENDIX A
iAPX 86,88 ABSOLUTE OBJECT
_______________
F_I_L_E_F_O_R_M_A_T_S~
I ntrod uction
The 8086 Absolute Object File Format herein described is a proper subset of the full
8086 Object File Formats. An absolute object file consists of a sequence of records
defining a single absolute module. An absolute module is defined as a collection of
absolute object information that is specified by a sequence of object records.
Definitions
This section defines certain terms fundamental to 8086 Relocation and Linkage
(R&L). The terms are ordered not alphabetically, but so you can read forward
without forward references.
Definition of Terms
OMF-acronym for Objl;!ct Module Formats
R&L-acronym for Relocation and Linkage
MAS-acronym for Memory Address Space. The 8086 MAS is one megabyte
(1,048,576 bytes). Note that the MAS should be distinguished from actual memory,
which may occupy only a portion of the MAS.
MODULE-an "inseparable" collection of object code and other information pro-
duced by a translator or by the LINK86 program. When a distinction must be made:
T-MODULE-denotes a module created by a translator, such as PL/M-86 or
ASM86, and
L-MODULE-denotes a module created by LINK86 from one or more constituent
modules. (Note that modules are not "created" in this sense by the iAPX86,88
Locater, LOC86; the output module from LOC86 is merely a transformation of the
input module).
Two observations about modules must be made:
1.
Every module must have a name, so that the iAPX86,88 Librarian, LIB86, has a
handle for the module for display to the user.
(If
there is no need to provide a
handle for LIB86, the name may be null.) Translators provide names for T-
modules, providing a default name (possibly the file name or a null name) if
neither source code nor user specifies otherwise.
2.
Every T-module in a collection of modules linked together may have a different
name, so that symbolic debugging systems can distinguish the various symbols.
This restriction is not required by R&L and is not enforced by it.
FRAME-a contiguous region of 64K of MAS, beginning on a paragraph boundary
(i.e., on a multiple of 16 bytes). This concept is useful because the content of the
four 8086 segment registers define four (possibly overlapping) FRAME's; no 16-bit
address in the 8086 code can access a memory location outside )f the current four
FRAME's. The FRAME starting at address OOOOH is FRAME O.
A-I
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