OEM MS OS/2: 1987-1990

When Microsoft started offering OS/2, the arrangement was roughly similar to how DOS 3.3 had been handled: Microsoft and IBM jointly developed the code, IBM maintained its own version, and Microsoft licensed an “adaptation kit” to OEMs. While the IBM and Microsoft versions were not identical, they were interchangeable from application perspective. There was no retail MS OS/2 package, and perhaps due to lower interest there also wasn’t a “packaged product” for OEMs (like there had been with MS-DOS since version 3.2).

Numerous OEMs licensed MS OS/2 1.0 in anticipation of it being the wave of the future, as Microsoft and IBM loudly proclaimed. OEM interest persisted through OS/2 1.1, but significantly waned by the time OS/2 1.2 was released. This coincided with Microsoft’s shift of focus towards Windows 3.0.

OEM MS OS/2 1.0 and 1.21

Pictured above are MS OS/2 1.0 (Epson OEM release) and MS OS/2 1.21 (Tandon OEM release). These were among the first and last OEM releases of OS/2. The Epson version was a relative latecomer, coming out in the second half of 1988. The Tandon version was released in summer 1990, when Windows 3.0 was already on the market.

The situation with MS OS/2 was not unlike MS-DOS at the time. While OEMs had opportunity to customize their releases, Microsoft had a complete OS which ran on standard IBM compatibles. By necessity, Microsoft made the vanilla releases of its OS/2 available as part of the infamous $3,600 MS OS/2 SDK.

As a consequence, OEMs selling highly IBM-compatible hardware (and that was most of them) had very little work to do when adapting MS OS/2. That applied to both the program code and the documentation.

Epson OS/2 1.0

The Epson release of MS OS/2 1.0 barely predated OS/2 1.1. It was somewhat customized, although it did not substantially differ from the SDK version of MS OS/2 1.0 (that is, the version of MS OS/2 shipped with the 1.02 release of the SDK).

Epson OS/2 Splash Screen

One of the scant differences was the addition of an OS2VER utility which ran in both OS/2 and DOS mode:

Epson OS/2 Version Utility

The documentation was likewise minimally customized but did make several references specific to Epson systems. There were three publications: A small Setup Guide booklet, and two larger ring-bound documents,  a Reference Manual and a Command Summary.

The software itself was shipped on three high-density 5¼” floppies. Two of those (Install and Program disks) were bootable, the third (Supplemental disk) was not.

Tandon OS/2 1.21

The Tandon release of MS OS/2 1.21 was so lightly customized that it was difficult to spot the differences. One of the very few modifications was the Tandon copyright displayed during boot:

Tandon OS/2 Boot

There were no additional utilities and the Presentation Manager was as shipped by Microsoft, with no mention of Tandon whatsoever:

Tandon OS/2 Desktop

The operating system was delivered on 9 high-density 5¼” floppies, a significant increase since the times of OS/2 1.0.

The printed documentation (a single large three-volume paperback) was entirely untouched by Tandon and looked exactly like Microsoft’s DOS and OS/2 manuals from the era. Only the book cover provided a clue that the manual had anything to do with Tandon.


No complete list of MS OS/2 OEMs is known, but it is known that OEM releases of MS OS/2 versions 1.0, 1.1, and 1.2 existed. The OEM list included at least AST, Compaq, Dell, DTK, Hewlett-Packard, Mitsubishi, NCR, NEC, NOKIA, Olivetti, Tandon, Tandy, Toshiba, Unisys, and Zenith.

The first OS/2 OEM release (not counting IBM’s) was from Zenith, in December 1987. Zenith collaborated with Microsoft on the OS/2 BAK (Binary Adaptation Kit). As a reward for helping Microsoft, Zenith was given a chance to release MS OS/2 before other OEMs.

It is unlikely that any OEM releases of MS OS/2 1.3 existed. OS/2 1.3 was released in 1991, at a time when IBM was officially an enemy and OS/2 was rapidly ceasing to exist in the world of Microsoft. MS OS/2 1.3 was most likely only available bundled with Microsoft LAN Manager 2.x, and that only because OS/2 was the only base OS the server portion of LAN Manager could run on at the time.

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18 Responses to OEM MS OS/2: 1987-1990

  1. Richard Wells says:

    Do you have dates of how long it was between IBM shipping their release of a version and the OEM release? What I remember it took almost a year after the release of IBM 1.2 for MS to release 1.21 and several months later IBM released 1.3. Quick check shows dates of November 1989, September 1990, and February 1991 respectively but those are IBM or MS announcements not any delays that OEM testing or modification might entail. In short, did Tandon manage to release 1.21 before IBM released 1.3?

    While IBM and MS disagreements didn’t exactly help OS/2 1.3 release by OEMs, other issues might have impacted OEM willingness to produce 1.3 releases. With the long lead time for 1.21, plenty of unsold copies remained at OEMs. IBM slashed prices on OS/2 1.3 (April 1991) and promised free upgrades to 2.0 might have made moving to OS/2 1.3 expensive for OEMs that considered matching IBM’s offer.

  2. Michal Necasek says:

    Let’s see… IBM OS/2 1.2 SE was announced on Sep 26, 1989 with availability on Sep 29. IBM OS/2 1.3 SE was announced on Oct 30, 1990 with availability on Nov 30, 1990. The non-IBM dates are much harder to pin down. My generic MS and Tandon OEM releases of MS OS/2 1.21 which both have files dated Jun 29, 1990. I can’t say exactly when Tandon released but I expect it would have been July or August 1990. So that still predates IBM’s 1.3 SE, but not by much.

    At the end of 1990s, it was pretty clear that Microsoft didn’t want OS/2 anymore, even if they claimed they’d still support OEMs (even with MS OS/2 2.0!). How seriously OEMs took such statements I don’t know. It’s hard to say how much Microsoft was dragging their feet making OS/2 BAKs available vs. how much the OEMs weren’t interested anymore.

  3. Michal Necasek says:

    And just to add to that, September 1990 was when IBM/MS publicly announced that IBM was taking over OS/2 development. That must have had some impact on the OEMs, no matter how much Microsoft claimed it’d continue to be business as usual.

  4. Andreas Kohl says:

    To my surprise there was at least one retail MS OS/2 from Microsoft Corp. called “MS-OS/2 for Mach 20” in 1988. The MACH 20 board offers 80286 CPU, Cache, memory expansion, floppy and harddisk controller, InPort-Mouse.

  5. Michal Necasek says:

    I’m not sure that counts as “retail” since it was only sold with hardware… but I do wonder if it was any different from the OS/2 SDK releases.

  6. James says:

    There was also Fujitsu version of Microsoft OS/2 1.1. I have 3.5″ floppies in original shrink wrap.

  7. Dylan Weber says:

    James pointed out the Fujitsu version, which had a couple of odd drivers bundled, typically. NCR did the same thing. I have only one NCR version, but several distributions of the Fujitsu MS-OS/2, for POS, ATM and storage library applications.

  8. techfury90 says:

    There were also at least two releases of MS OS/2 1.2x from NEC for the PC-98 line. It’s mentioned in my PC-9821Xa12’s “software supplement” manual, which also provides installation instructions for OS/2 2.11J.

    Sadly, I have never seen either around.

  9. Michal Necasek says:

    IBM Japan was pretty much a separate organization running things its own way, so there was not much knowledge about it or even contact from the US/European side. IBM also had Japanese PS/2 machines which I think were completely different from PC-98.

  10. techfury90 says:

    Yes, the PS/55 line. They had a special video card called the JDA- 1024×768 resolution, 24×24 fonts.

    I’ve actually found Japanese Warp 3, but it’s AT/PS/2 only. I’m uncertain as to if the 32 bit releases for PC-98 were sold by NEC or IBM. I know 1.2x was a NEC branded product. Also seems to have some kind of API for full screen PC-98 graphics.

    A shame, as I’d love to see just how perverse PC-98 OS/2 is.

  11. techfury90 says:

    More accurately:

    DOS/V is essentially an extension of the PS/55 version of PC-DOS that allowed it to run on generic VGA. AFAIK, for the most part, the JDA was about the only thing special about a PS/55 over a PS/2, plus many PS/2s could be equipped with a JDA and run PS/55 DOS. Officially supported by IBM for western developers.

    PC98 and PS/55 compatibility isn’t good at all. PC98 has a totally different BIOS and hardware, e.g. disk BIOS is INT 1Bh instead of 13h. At least it supports 65535 cylinders natively.

  12. Michal Necasek says:

    Japanese OS/2 Warp and I think 2.1 was published on DevCon. Of course those would have been specifically versions that run on hardware commonly available in the US 🙂 For anything else I suspect you need to have friends in Japan.

  13. Michal Necasek says:

    The PC98 is not a PC, that’s for sure. I have never seen one but I’m familiar with it just enough to know that the BIOS is completely different from IBM’s. What kind of compatibility problems did the PS/55 have?

  14. techfury90 says:

    As far as I know, the PS/55 didn’t really have any compatibility issues with “typical” PCs. Many models were literally PS/2s with the JDA card shoved in it. Some others were totally unique, but they all had base VGA as well as the JDA. The JDA card came in a bunch of different variants: the earlier ones used the MCA AVE connector (just like an 8514/A) and a BVE version that includes base VGA that came later on.

    Actually, later on, that card became an option because DOS/V came out and meant that IBM could sell PS/55s with VGA or XGA-2. My understanding is that DOS/V is literally an evolution of the PS/55’s Japanese DOS, down to that whole “English mode” thing. In fact, DOS/V has PS/55 JDA support, IIRC.

  15. techfury90 says:

    Warp 3 PC-98 has turned up on Yahoo Japan Auctions.

    Let’s hope I win it.

  16. Michal Necasek says:

    Good luck!

  17. techfury90 says:

    No luck. Bidding war ensued, I nearly won except the seller decided to block bids from the proxy I used with not even 7 minutes left on the clock. Damn.

  18. Yuhong Bao says:

    Thinking about it, I assume most of the MS OS/2 OEMs including Zenith were already using VGA in 1988, right?

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