Google Groups no longer supports new Usenet posts or subscriptions. Historical content remains viewable.
Dismiss

OMF v1.0?

258 views
Skip to first unread message

Andy McFadden

unread,
Jun 24, 2020, 7:15:41 PM6/24/20
to
Does anyone have an example of an Apple IIgs OMF v1.0 file? I'm trying to figure out if they actually exist "in the wild".

The Apple IIgs Programmer's Workshop Reference says:

"This section describes Version 2.0 of the Apple IIGS object module format(OMF). The System Loader supports files written in either Version 2.0 or Version 1.0 of the OMF. The APW Linker, however, creates load files that conform to Version 1.0 of the OMF. Notes in this section describe the differences between Version 1.0 and Version 2.0 of the OMF. The Compact utility program, described in Chapter 3, converts load files from Version 1.0 to Version 2.0."

The S16 files on the ProDOS 16 system disk use OMF v2.1. v2.0 is easy to find. Haven't seen a v1.0 yet.

One thing I can't figure out is why my code in CiderPress (reformat/Disasm.cpp) seems to diverge from the specification in the Workshop Reference book. Specifically, CiderPress ignores the last few fields (SEGNUM, ENTRY, DISPNAME, DISPDATA, LOADNAME). Those fields are present in the Object Module Format ERS (the internal doc used while the format was developed). The description of the VERSION field says:

"This 1 byte field indicates the version number of the Object Module Format with which the Segment is compatable[sic]. This field should be 1 for the initial specification of the Object Module Format."

A value of 1 corresponds to v2.0. So the ERS, from Aug 1986, indicates that v2.0 was the standard when the IIgs shipped. Perhaps v1.0 was a pre-release thing that only visible to early-access developers?

Unfortunately I don't remember what my source of information was when I wrote the code in CiderPress. I haven't been able to find anything that says OMF v1.0 lacked those fields, but maybe the code was written to handle real-world examples that I can no longer find.

Adding to my confusion is the Brutal Deluxe OMF Analyzer, which treats v1.0 the same way. I don't know if their code is based on the behavior of the system loader, or if they just saw my code and assumed I knew what I was doing. :-)

Stephen Heumann

unread,
Jun 24, 2020, 11:15:37 PM6/24/20
to
On 2020-06-24 23:15:40 +0000, Andy McFadden said:
> One thing I can't figure out is why my code in CiderPress
> (reformat/Disasm.cpp) seems to diverge from the specification in the
> Workshop Reference book. Specifically, CiderPress ignores the last few
> fields (SEGNUM, ENTRY, DISPNAME, DISPDATA, LOADNAME). Those fields are
> present in the Object Module Format ERS (the internal doc used while
> the format was developed). The description of the VERSION field says:
>
> "This 1 byte field indicates the version number of the Object Module
> Format with which the Segment is compatable[sic]. This field should be
> 1 for the initial specification of the Object Module Format."
>
> A value of 1 corresponds to v2.0. So the ERS, from Aug 1986, indicates
> that v2.0 was the standard when the IIgs shipped. Perhaps v1.0 was a
> pre-release thing that only visible to early-access developers?

There seems to be some confusion about version numbers. Appendix B of
the (16-bit) ORCA/M 2.0 manual contains documentation for OMF and says
the following:

"There are now three versions of the object module format. The first,
used with [eight-bit] ORCA/M 4.0, is labeled as version zero in the
header. The second, used by ORCA/M 4.1 on both eight-bit and
sixteen-bit Apple II computers, and by early versions of ORCA/M and the
Apple Programmer's Workshop on the Apple IIGS, has a one as the version
number. The newest version, version two, is currently used by ORCA/M. A
variant of this OMF format, known as version 2.1, adds an optional
field to the end of the header. The optional field is not needed, nor
is it created, by native development systems, although the ORCA
utilities and linker will accept OMF 2.1 format files."

It contains diagrams showing the headers for "Version 0", "Version 1",
and "Version 2.1". I believe version 2.0 would be the same as 2.1,
except without the extra TEMPORG field (the difference could be
detected based on DISPNAME).

I think "Version 1", "Version 2.0", and "Version 2.1" (as defined in
the ORCA/M manual) can all be found in various IIGS programs and
object/library files. If you're asking about "Version 0" then AFAIK it
was never used with IIGS stuff, only with eight-bit ORCA/M 4.0.
According to the manual, that version is indeed missing the SEGNUM,
ENTRY, DISPNAME, DISPDATA, and LOADNAME fields.

Incidentally, the even earlier versions of ORCA/M running on DOS 3.3
apparently used an even earlier version of OMF (pre-"Version 0"), as
documented in their manual:

https://archive.org/details/stx_Hayden_Software_ORCA-M_Macro_Assembler_manual/page/n277/


I haven't tracked down the old eight-bit versions of ORCA/M to get
examples of the OMF files they generate, but I think that's where you
would have to look if you want to find them.

--
Stephen Heumann

Kelvin Sherlock

unread,
Jun 25, 2020, 12:21:04 AM6/25/20
to
Before OMF was the IIgs executable format, it was the 8-bit ORCA
object module format.

quoting the 8-bit ORCA/M Assembler 4.1 documentation (circa 1986):

> ORCA languages take source files as input and produce object modules
as output. These object modules are then used as input to the link
editor. Object modules are contained in a special file type with a
file type number of $B1, which shows up as OBJ when cataloged from
ORCA.

> There are now two versions of the object module format. The first,
used with ORCA/M 4.0, is labeled as version zero in the header. The
second, used by ORCA/M 4.1 on both eight and sixteen bit Apple II
computers, and by the Apple IIGS Programmers Workshop on the Apple IIGS,
has a one as the version number. ...

--

The Byte Works has a copy of Cortland Programmer's Workshop 4.1A11,
the final version before it was APW. Note this is based on 8-bit ORCA/M
and included library files are version 2.0 OMF.

http://www.byteworks.us/Byte_Works/Morgue.html

The RELEASE.NOTES mentions in the Change History:

> (V1.0 A2 3 Feb 86)
> Version number for load file is now 1.

So if you want a version 1.0 file, you'll need to track down CPW Alpha 1
or ORCA/M 4.0 (for object files)

-------
ProLine: kelvin@pro-kegs

Stephen Heumann

unread,
Jun 25, 2020, 1:33:49 AM6/25/20
to
On 2020-06-25 03:15:35 +0000, Stephen Heumann said:
> I haven't tracked down the old eight-bit versions of ORCA/M to get
> examples of the OMF files they generate, but I think that's where you
> would have to look if you want to find them.

I looked through Opus ][ a bit and was able to find one OMF "version 0"
file on it:

ByteWorks/Eight.Bit/ORCA4.1/LIBRARIES/A..CLIB.A

This is the library for the eight-bit ORCA version of Small-C, which
was probably compiled with ORCA/M 4.0. The source code for it is also
on Opus ][, if you want to reference that.

--
Stephen Heumann

Antoine Vignau

unread,
Jun 25, 2020, 1:53:13 AM6/25/20
to
History and more within the single-sided document at http://www.brutaldeluxe.fr/documentation/cortland/v1_05_ObjectModuleFormatERS.pdf

Antoine

olivier...@cooperteam.eu

unread,
Jun 25, 2020, 3:14:23 AM6/25/20
to
Le jeudi 25 juin 2020 01:15:41 UTC+2, Andy McFadden a écrit :

> Adding to my confusion is the Brutal Deluxe OMF Analyzer, which treats v1.0 the same way. I don't know if their code is based on the behavior of the system loader, or if they just saw my code and assumed I knew what I was doing. :-)

I think my source of information for OMF Analyzer was a chapter in the Orca/M 2.0 Manual (+ GS/OS Reference book for 2.1 format).

I can't exclude a look into your CiderPress source code at the time but I don't think so :-)

Olivier

geoff body

unread,
Jun 25, 2020, 10:47:38 AM6/25/20
to
Andy,
I believe you are in the right section of the Apple IIgs Programmers Workshop Reading. Chapter 7 of the APW V1.0 draft, starting at 232-237 there is a clear definition of both OMF 1.0 and 2.0.
Ciderpress interprets the version 1.0 OMF header correctly, but displays as Version as 2.0. The first item in the segment header is bytecnt for 2.0, while for 1.0 it is BLKcnt. Having looked at the disk for TML PASCAL for APW vers 1.0 using Ciderpress and using the descriptions from Chapter 7, the header for TMLPASCAL and sample compiled programs have 1 in the Version field. The file structure matches the OMF 1.0 with segments also starting on block boundaries.
This confirms that The Version field in the segment header is the version number of the OMF.
http://www.goldstarsoftware.com/applesite/Documentation/AppleIIgsProgrammersWorkshop.PDF

Geoff B

Andy McFadden

unread,
Jun 25, 2020, 11:22:43 AM6/25/20
to
On Thursday, June 25, 2020 at 7:47:38 AM UTC-7, geoff body wrote:
> Ciderpress interprets the version 1.0 OMF header correctly, but displays as Version as 2.0. The first item in the segment header is bytecnt for 2.0, while for 1.0 it is BLKcnt.

Oh, if only. For VERSION=1, the first field is *either* BLKCNT or BYTECNT. For Load and Object files, it's a block count, and the overall file *usually* has a length that is a multiple of 512 (see e.g. BRIDGE.S16 on the Davex v1.23 disk for an example of a "short" binary). For static libraries, they apparently didn't want to waste space between segments, so it holds a byte count instead.

You have to know the ProDOS file type to interpret the file contents unambiguously. (This annoys me deeply.)

Anyway. I'm looking at the docs and think you're correct that I've mis-interepted the OMF version. The docs for OMF 2.0 and 2.1 (in the APW Ref and GS/OS ref, respectively) both say that the VERSION field is set to 2. The GS/OS ref also describes a REVISION field that is supposed to have the value 1, but declines to identify its location in the figure on page 447.

Andy McFadden

unread,
Jun 25, 2020, 11:26:53 AM6/25/20
to
On Wednesday, June 24, 2020 at 8:15:37 PM UTC-7, Stephen Heumann wrote:
> I think "Version 1", "Version 2.0", and "Version 2.1" (as defined in
> the ORCA/M manual) can all be found in various IIGS programs and
> object/library files. If you're asking about "Version 0" then AFAIK it
> was never used with IIGS stuff, only with eight-bit ORCA/M 4.0.
> According to the manual, that version is indeed missing the SEGNUM,
> ENTRY, DISPNAME, DISPDATA, and LOADNAME fields.

This makes sense. CiderPress is interpreting the version field incorrectly.

Since VERSION=0 wasn't really used for 16-bit code, it can be ignored entirely by the IIgs code formatter.

Andy McFadden

unread,
Jun 25, 2020, 11:42:39 AM6/25/20
to
On Thursday, June 25, 2020 at 12:14:23 AM UTC-7, olivier...@cooperteam.eu wrote:
> I think my source of information for OMF Analyzer was a chapter in the Orca/M 2.0 Manual (+ GS/OS Reference book for 2.1 format).

That would make sense. There's a comment in the CiderPress sources that says:

* Orca/APW libs seem to use version 1 with a byte count in the
* first field, but the "LLRE" app has version 1 with a block count.
* The spec is pretty clear, so it looks like somebody's library
* builder screwed up.

This behavior is explained in the Apple IIgs Programmers Workshop Reference, so I was clearly getting my 1.0/2.0 info from somewhere else. I just couldn't figure out where. :-)

Stephen Heumann

unread,
Jun 25, 2020, 2:41:58 PM6/25/20
to
On 2020-06-25 15:22:42 +0000, Andy McFadden said:
> Oh, if only. For VERSION=1, the first field is *either* BLKCNT or
> BYTECNT. For Load and Object files, it's a block count, and the
> overall file *usually* has a length that is a multiple of 512 (see e.g.
> BRIDGE.S16 on the Davex v1.23 disk for an example of a "short" binary).
> For static libraries, they apparently didn't want to waste space
> between segments, so it holds a byte count instead.
>
> You have to know the ProDOS file type to interpret the file contents
> unambiguously. (This annoys me deeply.)

Well, static libraries would normally start with a library dictionary
segment, which could be detected independently of the file type. Are
there version 1 files where the presence or absence of a library
dictionary segment does not line up with the use of BLKCNT vs. BYTECNT?

> Anyway. I'm looking at the docs and think you're correct that I've
> mis-interepted the OMF version. The docs for OMF 2.0 and 2.1 (in the
> APW Ref and GS/OS ref, respectively) both say that the VERSION field is
> set to 2. The GS/OS ref also describes a REVISION field that is
> supposed to have the value 1, but declines to identify its location in
> the figure on page 447.

AFAIK that REVISION field doesn't really exist. I think the
documentation updates for version 2.1 were done a bit sloppily. There
are also a couple places in the GS/OS Reference where the specified
offsets do not properly account for the tempORG field.

--
Stephen Heumann

Andy McFadden

unread,
Jun 25, 2020, 4:01:56 PM6/25/20
to
On Thursday, June 25, 2020 at 11:41:58 AM UTC-7, Stephen Heumann wrote:
> > You have to know the ProDOS file type to interpret the file contents
> > unambiguously. (This annoys me deeply.)
>
> Well, static libraries would normally start with a library dictionary
> segment, which could be detected independently of the file type. Are
> there version 1 files where the presence or absence of a library
> dictionary segment does not line up with the use of BLKCNT vs. BYTECNT?

My approach is to parse assuming it's not a library. If the parsing fails, or a LibDict segment is encountered, restart with the assumption that it is a library and see if that works.

The basic premise of the file format -- that OMF is just a rough structure to hold various things, and you need to know what the thing is ahead of time -- annoys me, but it wouldn't be so bad if you could easily parse the outer container. Having to parse the contents of a segment to know how to find the next segment is Just Wrong(tm) when the file structure is supposed to be a chunk list.

(FWIW, the specification says the library file "includes" a segment, but does not declare that it must appear first. In practice I think it will always be first because that's how the tools work.)

> AFAIK that REVISION field doesn't really exist. I think the
> documentation updates for version 2.1 were done a bit sloppily. There
> are also a couple places in the GS/OS Reference where the specified
> offsets do not properly account for the tempORG field.

Yup, I think the only way to tell the difference is by DISPNAME > $2a.

Figure F-2 also shows "blockCount" where it should say SEGNAME.

> ByteWorks/Eight.Bit/ORCA4.1/LIBRARIES/A..CLIB.A

Thanks! CiderPress does handle that one. Interesting that the other libs in that dir use the newer OMF format.

Stephen Heumann

unread,
Jun 25, 2020, 5:44:39 PM6/25/20
to
On 2020-06-25 20:01:55 +0000, Andy McFadden said:
> My approach is to parse assuming it's not a library. If the parsing
> fails, or a LibDict segment is encountered, restart with the assumption
> that it is a library and see if that works.

That sounds reasonable, although I suspect that in practice the lib
dict is always first.

>> AFAIK that REVISION field doesn't really exist. I think the
>> documentation updates for version 2.1 were done a bit sloppily. There
>> are also a couple places in the GS/OS Reference where the specified
>> offsets do not properly account for the tempORG field.
>
> Yup, I think the only way to tell the difference is by DISPNAME > $2a.

DISPNAME is normally 44 ($2C) in OMF v2.0, and 48 ($30) in OMF v2.1.
(But this may differ between segments--in particular, there are many
files where the ~ExpressLoad segment has DISPNAME=44 but other segments
have DISPNAME=48.)

This is one of the points that the GS/OS reference gets wrong--it says
"Currently, DISPNAME = 44" even though it's documenting OMF v2.1. It
also shows DISPDATA and tempOrg as both being at offset $2A in Figure
F-2, when tempOrg must actually be at offset $2C.

>> ByteWorks/Eight.Bit/ORCA4.1/LIBRARIES/A..CLIB.A
>
> Thanks! CiderPress does handle that one. Interesting that the other
> libs in that dir use the newer OMF format.

The other files in that directory are from ORCA/M 4.1, so they use
OMFv1. ORCA Small-C was originally a separate product, and its library
must have been built with ORCA/M 4.0.

--
Stephen Heumann

Andy McFadden

unread,
Jun 25, 2020, 7:41:59 PM6/25/20
to
On Thursday, June 25, 2020 at 2:44:39 PM UTC-7, Stephen Heumann wrote:
> > Yup, I think the only way to tell the difference is by DISPNAME > $2a.
>
> DISPNAME is normally 44 ($2C) in OMF v2.0
[...]
> also shows DISPDATA and tempOrg as both being at offset $2A in Figure
> F-2, when tempOrg must actually be at offset $2C.

See if you can guess which figure I was looking at when I wrote the above. :-)

Sometimes I miss paper documentation... when something is wrong you can fix it with a pencil. I'm entirely too lazy to dig those out of the many boxes of stuff though, so I'll make do with the scans.

geoff body

unread,
Jun 26, 2020, 9:51:22 AM6/26/20
to
Having the File Type would help to minimise guessing
Based on File Types should be able to locate types that have segments
load segment header(s)
check the version of OMF (1 or 2 are valid)
Check KIND, which changes position and size based on OMF, OMF 1.0 at offset $0C (size 8 bits), or OMF 2.x at offset $14 (size 16 bits)
KIND will help identify segment types which should make it easier to process a segment of a specific type.

See page 236 of Apple IIgs Programmers Workshop for description of both versions of KIND
eg. bits 0-4 of Kind = 08 -> library dictionary segment

Geoff B

Andy McFadden

unread,
Jun 27, 2020, 1:25:32 PM6/27/20
to
On Thursday, June 25, 2020 at 12:14:23 AM UTC-7, olivier...@cooperteam.eu wrote:
> I think my source of information for OMF Analyzer was a chapter in the Orca/M 2.0 Manual (+ GS/OS Reference book for 2.1 format).

For anyone else looking for this: on the Opus ][ CD, look in the "Documentation:PDF Documentation" folder. The file "GS-04 ORCA/M 2.0.pdf" is the relevant one. Appendix B describes OMF; page 488 shows v0, v1, and v2.1 side-by-side.

It uses slightly different names (e.g. BLOCKCOUNT vs. BLKCNT), and doesn't describe the v1 Object/Library behavior, noting simply "several features that deal with relocatable code and libraries have been omitted." Only Load files are documented.

Andy McFadden

unread,
Jul 12, 2020, 2:29:37 PM7/12/20
to
CiderPress has been updated. The fixed OMF version reporting is in a pre-release, v4.0.4-d2. https://github.com/fadden/ciderpress/releases if you're dying to see the correct value.

The OMF viewer in SourceGen handles all versions, including "v0" (tested with the library mentioned earlier in this thread). It also goes deeper than CiderPress, decoding records in object and library files, so if you were curious to see expressions in compiler intermediates you can now do so from the comfort of Windows. :-)

The OMF converter does more or less what the GS/OS system loader does, though I'm still a little vague on the interaction with some of the KIND flags when ORG is zero.

geoff body

unread,
Oct 12, 2021, 8:53:36 PM10/12/21
to
To anyone interested after having had a poke about MPW tool LinkIIgs there is a procedure check_header, the code is interesting with regard to revision field.
It appears that the revision field for version 2.X reuses the LCBANK field from OMF 1.0.

if ( *(Buf + 14) != 0x04
|| *(Buf + 32) != 0x00
|| *(Buf + 8) > 0x00FFFFFF
|| *(Buf + 24) > 0x00FFFFFF
|| *(Buf + 28) > 0x00FFFFFF
|| *(Buf + 36) > 0x00FFFFFF
|| *Buf < 48 )
{
fprintf(stderr, "%sBad Segment Header found in Segment $%hX in file \"%s\\r", );
fatal(2, 0);
}

else if (*(Buf + 15) < 0x01 || *(Buf + 15) > 0x02)
{
fprintf(stderr, "%sUnsupported OMF Version (%hX) found in Segment $%hX in file \"%s\"\r");
fatal(2, 0);
}
else
{
if ( *(Buf + 15) == 0x02)
{
if ( *(Buf + 33) > 0x01)
{
fprintf(stderr, "%sUnsupported OMF Revision (%hX) found in Segment $%hX in file \"%s\"\r",);
fatal(2, 0);

fadden

unread,
Oct 13, 2021, 6:54:25 PM10/13/21
to
On Tuesday, October 12, 2021 at 5:53:36 PM UTC-7, gbo...@bigpond.com wrote:
> It appears that the revision field for version 2.X reuses the LCBANK field from OMF 1.0.
[...]
> {
> if ( *(Buf + 15) == 0x02)
> {
> if ( *(Buf + 33) > 0x01)
> {
> fprintf(stderr, "%sUnsupported OMF Revision (%hX) found in Segment $%hX in file \"%s\"\r",);

Interesting... you think at some point the tools used the "undefined" (nee LCBANK) field to differentiate between v2.0 and v2.1 segments?

It doesn't appear to be nonzero in the v2.1 files I've looked at that were generated on a IIgs. Maybe someone thought it *might* be used and planned ahead?

geoff body

unread,
Oct 13, 2021, 8:14:28 PM10/13/21
to

> It doesn't appear to be nonzero in the v2.1 files I've looked at that were generated on a IIgs. Maybe someone thought it *might* be used and planned ahead?

Do you have samples that you believe are OMF V2.1 files and where to find them?

fadden

unread,
Oct 14, 2021, 1:00:39 AM10/14/21
to
On Wednesday, October 13, 2021 at 5:14:28 PM UTC-7, gbo...@bigpond.com wrote:
> Do you have samples that you believe are OMF V2.1 files and where to find them?

YankIt and the HardPressed PIF have OMF v2.1 segments. YankIt is here: https://fadden.com/apple2/dl/yanksrc.shk

I'm looking at the header with the SourceGen OMF conversion tool. For example:

BYTECNT $00e4f7 bytes
RESSPC $000000
LENGTH $00c962
undefined $00
LABLEN $00 variable length
NUMLEN $04 must be 4
VERSION $02 v2.1
BANKSIZE $010000
KIND $0000 Code
undefined $0000
ORG $000000 relocatable
ALIGN $000000 no alignment
NUMSEX $00 must be 0
undefined $00
SEGNUM $0002
ENTRY $000000
DISPNAME $0030
DISPDATA $0045
TEMPORG $000000
LOADNAME
SEGNAME

The only way to tell v2.0 from v2.1 is by looking at DISPNAME. If it's 44 ($2c) then it's a v2.0 header, if it's greater than that then it has additional fields (TEMPORG). LCBANK is the undefined field after NUMSEX, but it always seems to hold zero.

geoff body

unread,
Oct 16, 2021, 12:25:15 AM10/16/21
to

Going to try and generate a OMF 2.1 segment with MPW AsmIIGS.
Then see if it flows through the other tool(s) including the linker -> LinkIIgs.

geoff body

unread,
Oct 16, 2021, 10:47:23 AM10/16/21
to
MPW AsmIIgs v1.1 generates Obj files with the TempOrg flagged in the header if used as a directive in the source.
discussed in the manual for MPW AsmIIgs manual
Linking produces output no longer needing the TempOrg detail.
based on changes for the MPW IIgs tools Apple made changes to MakelibIIgs to handle output by produced by ORCA 2.0 that was adding an empty TempOrg, see reference below.


MPW IIGS Tools V1.3

MakeLibllGS:
• ORCA 2.0 assembler is producing object files with the TempOrg field in the segment
headers, even though it's not using the field. This offsets the dispName and dispData
field values. MakeLib is not adjusting these values when it writes the segment headers
out to the library file without the TempOrg field. Fixed by having WriteSegmentHeader
calculate the proper values.

LinkUGS:
• LinklIGS v.1.1 is much faster and uses less memory than v.1.0.
• LinklIGS will use MultiFinder memory during links if the '-mf option is specified. This allows
the memory partition for MPW itself to be kept smaller, leaving more room for other applications
when LinklIGS is not being used.
• LinklIGS supports OMF Version 2.1 which includes: Object Segments having a tempORG
(temporary origin); Skip Object Segments; and Bank Relative Object Segments.

MPW sample files with associated MPW dumped segment headers.
https://drive.google.com/drive/folders/1cY67HANwb6NsQhogJhc1Ijz2Y9ERM1p2?usp=sharing

geoff body

unread,
Oct 16, 2021, 10:52:12 AM10/16/21
to

fadden

unread,
Oct 16, 2021, 6:36:21 PM10/16/21
to
ProDOS.FST.Obj has one v2.1 segment (BOOT_CODE), and sure enough:

Alignment : $00000000 0
Number sex : $00 0
Revision : $01 1

gquit.obj also has one v2.1 segment (LOAD_APP), also with a nonzero value. So the Mac tools appear to be using the "undefined" field that follows NUMSEX to be the minor version number.

The v2.1 segments in YankIt/HP have a tempORG field with zero in it, which is probably what the remarks about "not using the field" mean. The segments are not technically v2.0, since the tempORG field didn't exist in the v2.0 definition... but if it's not really being used, does it count?

Maybe the Orca-generated segments should be called v2.0.1?

geoff body

unread,
Oct 17, 2021, 12:33:36 AM10/17/21
to
According to GSOS reference V5.0 and later.
tempORG A 4-byte field indicating the temporary origin of the Object segment. A nonzero value indicates that all references to globals within this segment
will be interpreted as if the Object segment started at that location.
However, the actual load address of the Object segment is still
determined by the ORG field.

It would appear that a OMF 2.1 header would/should only apply to these Object segments, which also includes Libraries that have included a OBJ with OMF 2.1.

Maybe should ask Mike Westerfield if there is any further documentation on OMF 2.1 format.
0 new messages