OS/2 Museum

Microsoft OS/2 1.3… But Which One?

Posted on May 7, 2014 by Michal Necasek

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.

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.

Continue reading →

Posted in LAN Manager, Microsoft, OS/2 | 26 Comments

Have You Seen This Board?

Posted on May 2, 2014 by Michal Necasek

The OS/2 Museum recently acquired this mystery 386 board (click on the image to see a high-resolution photo):

This is in theory a killer 386 board: onboard Am386DX-40, a socket for a replacement 386 or 486DLC processor, a FPU socket, 256KB cache, 8 SIMM slots for up to 32MB RAM, six 16-bit ISA slots, and best of all, a clock chip that can be set via jumpers to 16/20/25/33/40/50 MHz. Anyone familiar with typical 386 systems knows that such boards with user-selectable clock frequency are rather uncommon. Changing the clock speed normally involves replacing the crystal, which is hardly something one would want to do regularly. Continue reading →

Posted in 386 | 23 Comments

From the Annals of Branding

Posted on April 25, 2014 by Michal Necasek

The following picture shows four essentially identical Intel processors in the top row:

The real difference is that some of them are fabricated on an older process and thus sport a larger die size than others. (They’re also not all rated to operate at the same frequency, but that is not a design difference).

The more obvious difference is the labeling. From plain chips to i386 to i386 DX. The chips neatly illustrate an important chapter in Intel’s history. The leftmost chip was manufactured sometime in early 1988 and doesn’t look very different from the original 386s, or any other Intel chip of the era. It’s simply a slab of gray-brown ceramic with etched markings. The only noteworthy feature is the double-sigma (ΣΣ) marking indicating a 386 which reliably performs 32-bit operations. Continue reading →

Posted in 386, Intel | 14 Comments

OEM MS OS/2: 1987-1990

Posted on April 18, 2014 by Michal Necasek

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.

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. Continue reading →

Posted in Microsoft, OS/2 | 18 Comments

Multitasking MS-DOS 4.0, Goupil OEM

Posted on April 9, 2014 by Michal Necasek

The recently unearthed copy of the near-mythical Multitasking (aka European) MS-DOS 4.0 clearly did not want to be alone. James Lariviere, a kind reader of this blog, provided a disk image of multitasking DOS 4 which was released in 1986 by the French company SMT Goupil.

Microsoft’s contract with Goupil was the main reason why multitasking DOS 4 was completed at all. Goupil was the most important and perhaps even only OEM shipping multitasking DOS 4 (British ICL was the primary customer of the updated multitasking DOS 4.1 in 1987).

The machine that multitasking DOS 4 ran on was the Goupil G4, and a brief look at the machine’s specs reveals why Goupil was interested in multitasking DOS 4: The G4 was equipped with an 8 MHz Intel 80186 processor. Continue reading →

Posted in DOS, Microsoft, OS/2 | 29 Comments

The ISA OSC Mystery

Posted on April 3, 2014 by Michal Necasek

About twenty years ago I ended up with a spare ISA graphics card from an upgraded computer. It was a SVGA card based on the Cirrus Logic CL-GD5422 chip, equipped with 1 MB video memory.

This was a very cheap graphics card sold as part of a low-end PC in 1993 by ESCOM, a large European (originally German) PC retailer. It was a basic but hassle-free card, it was no speed demon but did its job well.

Now fast forward nearly twenty years. In the quest for the Ultimate Museum PC, I tried this old VGA card in a 440BX board (Abit BP6). It didn’t work. At all. There was no video signal whatsoever. I assumed that the card was most likely dead, because other (even older) ISA VGA cards did work in the same 440BX system. But I didn’t throw the card out… just in case.

Continue reading →

Posted in Cirrus Logic, Graphics, PC hardware | 15 Comments

386 ZIF Socket?

Posted on March 27, 2014 by Michal Necasek

I have a problem:

Anyone familiar with 386 LIF (Low Insertion Force) sockets knows that the trouble isn’t installing the processors—that indeed doesn’t require much force and is easy to do. The real problem is getting the processor out without bending the pins and/or damaging the ceramic package.

This got me wondering… surely it would be possible to build a ZIF (Zero Insertion Force) socket for the 132-pin PGA used on 386s, just like the larger sockets used for 486 processors? Is anyone familiar with such a thing? Continue reading →

Posted in 386 | 18 Comments

MS-DOS 1.1, 2.0 Source Code Released

Posted on March 25, 2014 by Michal Necasek

In cooperation with the excellent Computer History Museum in Mountain View, Microsoft released the source code to MS-DOS 1.1, MS-DOS 2.0, and Microsoft Word for Windows 1.1a.

Here’s hoping that this is a sign of things to come and Microsoft will also release the source code to historic versions of Windows 1.x, 2.x and 3.x, further versions of MS-DOS—and maybe even OS/2 1.0!

The poor CHM server is currently suffering from a severe overload so actually looking at the goodies will have to wait… Continue reading →

Posted in DOS, Microsoft, PC history | 53 Comments

IBM OS/2 1.0 in a VM

Posted on March 21, 2014 by Michal Necasek

As previously mentioned, IBM’s OS/2 1.0 and 1.1 is extra unfriendly to modern hypervisors. To recap, there is a curious difference between IBM’s and Microsoft’s kernels in OS/2 1.0/1.1 with regard to mode switching.

For reasons that aren’t very clear, IBM’s kernels implement only 286 style mode switching: In order to get from protected back to real mode, the processor is reset and the BIOS told where to resume execution. On the other hand, Microsoft’s kernels have had (faster) 386-specific code ever since the first OS/2 SDK beta from April 1987.

To make matters more interesting, the OS/2 kernel is also famous for using the undocumented LOADALL instruction when running on a 286. Yet IBM’s OS/2 did run on 386 AT clones of the era. How is that possible? Continue reading →

Posted in IBM, Microsoft, OS/2, VirtualBox, Virtualization | 36 Comments

What’s in a Name?

Posted on March 7, 2014 by Michal Necasek

The following four processors are much more similar than one might think:

486 aficionados will recognize the processors made by IBM, ST Microelectronics, and Texas Instruments to be essentially one and the same model—Cyrix 486DX. Continue reading →

Posted in 486, Cyrix | 14 Comments