Microsoft OS/2 1.3… But Which One?

A recent inventory at the OS/2 Museum revealed that two seemingly identical sets of Microsoft OS/2 1.30.1 disk images were in fact not identical at all. Probably thanks to the twilight status of OS/2 at Microsoft in the days of OS/2 1.3, Microsoft managed to confuse things to the point that it had to issue KB article Q99245 explaining the differences.

LAN Manager 2.2

The trouble was that all the versions reported themselves as 1.3/1.30.1, and the SYSLEVEL.OS2 file which is supposed to differentiate between minor patch versions was exactly identical in all cases. However, timestamps and sizes of many system files (including the kernel, OS2KRNL) were not identical.

As the above mentioned KB article indirectly hints, the most differences between the releases were in the LADDR (Layered Adapter Device DRiver) subsystem of OS/2. LADDR was a technology developed by Microsoft in the days of OS/2 1.2 in order to better support the multitude of new storage controllers.


Starting around 1990, Microsoft lost interest in OS/2 as a desktop operating system (that was now DOS + Windows 3.0). But OS/2 still played a very important role at Microsoft as the basis of LAN Manager and SQL Server, Microsoft’s flagship server products.

While LAN Manager 1.x was sold as an OEM product, LAN Manager 2.0 was distributed almost exclusively directly through Microsoft. And that meant MS OS/2 needed to support common OEM hardware.

For a server OS, graphics was not an issue, but storage most certainly was. To ease supporting varied hardware and add new feature (such as fault tolerance), Microsoft developed the layered storage driver model known as LADDR. Instead of a monolithic DISK01.SYS driver, the drivers were broken down into smaller, more manageable chunks.

On a typical AT clone, ESDI-506.BID was the low-level IDE driver, DISK.TSD was a generic fixed disk driver, while FATCACHE.VSD or FT.VSD (FT stood for Fault Tolerance) were add-on modules. IOS1X.SYS, IOCFG01.SYS and IORUN.SYS were core LADDR components, shared among hardware implementations.

The architecture looked more like that of Windows NT than OS/2 1.x. Among other things, LADDR introduced SRBs (SCSI Request Blocks) and OS/2 1.3 with LADDR supported SCSI tape drives (important for tape back-up on servers) and CD-ROMs.

MS OS/2 1.3 Releases

Available information indicates that Microsoft never released OS/2 1.3 as a standalone product and probably also never shipped it to any OEMs. Microsoft did ship OS/2 1.3 as part of LAN Manager, and even published KB articles identifying the delivered files together with their sizes and timestamps.

The following KB articles were extracted from an old MSDN Library CD, since they are either very difficult to find or incomplete on-line. There are the following articles listing LAN Manager installation disk contents:

  • Q97725 for LAN Manager 2.1 (November 1991)
  • Q97726 for LAN Manager 2.1a (August 1992)
  • Q97724 for LAN Manager 2.2 (November 1992)

It’s worth remembering that IBM released OS/2 2.0 in April 1992, which means that Microsoft kept updating OS/2 1.3 even when OS/2 2.0 was already on the market; in fact LAN Manager 2.1a added support for OS/2 2.0 clients (files in the WKSTA20 directory on the OS/2 Workstation disk).

To make things even more complicated, Microsoft wasn’t done with OS/2 1.3 in November 1992. First there was LAN Manager 2.2a, except there really wasn’t, as Q96439 explains. But then there was LAN Manager 2.2b, which is covered in Q113604. Unlike the previous releases, this was only an update to be applied to LAN Manager 2.2/2.2a.

The Q1113604 KB article mentions that among others, OS2KRNL was updated in LAN Manager 2.2b. Unfortunately no file sizes or timestamps were provided, so spotting the LAN Man 2.2b version of OS2KRNL could be tricky.

To summarize, there were at least four different versions of OS/2 1.3 released by Microsoft. While they are not easily distinguished, their existence was clearly documented by Microsoft.

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21 Responses to Microsoft OS/2 1.3… But Which One?

  1. Trowa Barton says:

    The difference between 2.2 and 2.2a is “only in the absence of a single
    NDIS driver.” That’s pretty similar to XP SP1 vs SP1a which only removed MS’s JavaVM. Both were also due to “licensing reasons”.

    And these multiple versions of LAN Manager, each one was a complete purchase? Were there service pack like upgrades?

  2. Michal Necasek says:

    2.0/2.1/2.2 were all separate purchases. It was possible to upgrade existing installations, but there was no “service pack” type upgrade. Only 2.2b was a patch (and not available as a full product at all).

  3. Chris W. says:

    Slightly OT but Michael, given that you seem to be an expert on early OS/2 – do you know of any lists/references of early OS/2 1.x compatible applications?

  4. Michal Necasek says:

    Not online, and I’ve never seen a good list showing only apps that were really completed and available for purchase. I do have a printed book listing OS/2 apps but with most entries it’s difficult to confirm that the software actually shipped.

    The major Microsoft products were LAN Manager, SQL Server, Excel, and Word, as well as numerous development tools that were used even by DOS/Windows developers (Microsoft C, MASM, BASIC, etc.). The major IBM product was probably the Extended Edition and various connectivity products.

    There were quite a few development tools available for OS/2 1.x (C/C++, Fortran, Smalltalk, Pascal, etc.). One of the biggest GUI apps was Aldus PageMaker. There was supposed to be AutoCAD 10 or so but I’m not certain it ever materialized.

    In general there was a lot of custom development done on OS/2 1.x (and 2.x as well) by various large companies which is why development tools are so disproportionately represented. Things like airline reservation systems, banking software, etc.

  5. James says:

    Display Write 4 was availble for Operating System/2 1.2 Standard Edition

  6. Richard Wells says:

    A surprising large amount of OS/2 1.x software was support for specialized hardware. Interactive prompting systems for telephones were the area I got to work on.

    OS/2 commercial software sometimes existed in a kind of twilight region: beyond beta but not available boxed in stores. To get an OS/2 version, it was necessary to know someone that could indicate the correct employee at the vendor and convince him to accept payment and proof of ownership of a non-OS/2 version. I suspect what few copies existed were tested at the handful of large companies that contemplated large scale OS/2 1.x deployments.

  7. Michal Necasek says:

    Yes, OS/2 was often used for industrial control and automation type of things, both 1.x and 2.x. ATMs and voice mail systems were just a small subset of it. I didn’t work with OS/2 1.x but I worked on several custom OS/2 projects up into the mid-2000s, when most people thought OS/2 didn’t exist anymore (yet new systems running OS/2 were still being deployed).

    I’m guessing that OS/2 was successful in this arena because it was the first mass-market OS with a decent GUI and good multitasking capabilities. Windows 3.x or even 9x wasn’t much of an alternative, and it took NT many, many years to get up to speed.

  8. Yuhong Bao says:

    Yea, it is unfortunate MS turned OS/2 2.x into an entire fiasco and it was one of my favorite topics.

  9. Michal Necasek says:

    Yes, we noticed 🙂

  10. Peter Godwin says:

    In Australia at least, I see more crashed Windows XP based ATMs then I recall ever seeing crashed OS/2 based machines (only 1 I can recall).

    I’m guessing the relatively simple architecture of OS/2 must have contributed, as well I’m sure people like yourselves writing the device drivers 😉

    That and you didn’t do the UI in Flash…

  11. Michal Necasek says:

    I don’t know, XP isn’t unstable as such… but bad drivers will kill it, and the driver model is insanely complex (i.e. very difficult to get 100% right). Could be hardware, too, if they have trouble with, say, inadequate cooling.

  12. James says:

    In our trusty Mitel PBX, it ran OS/2 1.x (at least during 1997-1999), then we worried about Y2K, etc. and thought about upgrading to OS/2 Warp 4 (did not work) and even with Windows NT OS/2 subsystem, which also was an epic fail.

  13. Yuhong Bao says:

    Unrelated, but another favorite is that the Morris worm dates back to late 1988 when MS was starting the development of OS/2 2.0 and NT OS/2. Yea, I am talking about the decision to use a flat address space (instead of segmented) with default image base addresses which was what made buffer overflow etc exploits really popular.

  14. Michal Necasek says:

    I would not expect the NT OS/2 subsystem to work… Warp 4 should have, but not necessarily without some work, especially if the software used some custom device drivers etc. (which it probably did).

  15. Tobis87 says:

    BusLogic SCSI driver for OS/2 LADDR (for CD-Rom in VirtualBox):

  16. Michal Necasek says:

    Never tried that driver myself. Does it work?

  17. Tobis87 says:

    Yes, it does work:

    You can even boot with SCSI, but I don’t know if Fatcache will then be used.

  18. S Duggan says:

    “Available information indicates that Microsoft never released OS/2 1.3 as a standalone product and probably also never shipped it to any OEMs.”

    Dunno about this. I have an OEM boxed MS OS/2 1.30 set. The disks were 3.5″. I bought this from a retail store in London many years ago. This is the box it came in:

    The rear side of the box specifically mentions 1.3 and its features, so was not a generic box.

  19. Michal Necasek says:

    Actually, that’s not an OEM version. That looks like a retail Microsoft product… which is even more interesting! Any chance to get at the disk contents? All MS OS/2 1.3 versions I’ve seen so far were part of LAN Manager, but this doesn’t seem to be. It’s also from 1991, right around the time when Microsoft officially dumped OS/2.

  20. S Duggan says:

    It has a superimposed label on the top that says OEM, which is probably a consequence of the licence rather than the packaging since no third party manufacturer has made his mark, such as Zenith or Nokia did with earlier releases. Otherwise everything else looks pretty much as per retail. There is no networking/LAN element inside, so very much an SE release.

    Picture of the OEM barcode label on the box top:
    Picture 1 of the floppies:
    Picture 2 of the floppies:
    Contents of the box:

    To be honest, I did not think this was in any way rare. I have installed this on a PS/2 55Sx many years ago but not touched it since, so I do not know if the disks are holding up. If this is of interest, let me know and I will try to get images to you at some stage if you can suggest a host.

    I have recently acquired a slew of MS OS/2 Toolbox/Developer floppies (5.25″) of a slightly older vintage and will probably want to find time to see if those are still readable. From what I can remember, the dates seem to range from 1985 to 1989 with some undateable, so they are probably suffering from bitrot by now.

  21. Michal Necasek says:

    Thanks for the pictures. I assume you got the e-mail I sent directly.

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