Category Archives: OS/2

Ladders and Dragons

Posted on December 28, 2014 by Michal Necasek

While looking at the Windows 95 disk subsystem, something seemed oddly familiar. The nagging feeling was confirmed by the Windows 95 DDK documentation (a file called BLOCK.DOC). The new Windows 95 layered block device driver model called “Dragon” wasn’t all … Continue reading →

Posted in OS/2, PC history, SCSI, Windows 95 | Leave a comment

OS/2 Kernel Debugger and MVDM Interrupts

Posted on August 29, 2014 by Michal Necasek

While working on an unrelated problem, I noticed a strange behavior of one of my OS/2 VMs running OS/2 Warp 4.52. To cut a long story short, if an unhandled floating-point exception occurred in a DOS window (VDM, or Virtual … Continue reading →

Posted in Bugs, Debugging, OS/2 | 12 Comments

Windows Presentation Manager Documentation

Posted on July 20, 2014 by Michal Necasek

The OS/2 Museum just posted a three-volume set of draft Windows Presentation Manager reference documentation. This refers to the OS/2 Presentation Manager GUI but highlights the story Microsoft pushed in 1987: Windows and OS/2 both used the same graphical user … Continue reading →

Posted in Documentation, Microsoft, OS/2 | 5 Comments

OS/2 Programmer’s Toolkit

Posted on July 11, 2014 by Michal Necasek

For those wishing to write OS/2 1.x programs, the complete Microsoft OS/2 Programmer’s Toolkit documentation is now online. This is Microsoft’s programming documentation for OS/2 1.0 programming. It is worth noting that IBM’s programming documentation was different; worse yet, IBM’s … Continue reading →

Posted in Development, Documentation, Microsoft, OS/2 | 2 Comments

Weekend Reading, OS/2 and Windows

Posted on July 4, 2014 by Michal Necasek

In a recent post I mentioned that the OS/2 Museum’s stack of PC Tech Journal issues ironically does not include the first PCTJ issue devoted to OS/2. Thanks to pcjs.org, the October 1987 issue of PCTJ can now be read … Continue reading →

Posted in Documentation, Microsoft, OS/2, Windows | 3 Comments

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 … Continue reading →

Posted in Microsoft, OS/2 | 25 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 … 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 … Continue reading →

Posted in DOS, Microsoft, OS/2 | 29 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, … Continue reading →

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

Fantasy History at Ars Technica

Posted on November 26, 2013 by Michal Necasek

Ars Technica today published an article titled “Half an operating system: The triumph and tragedy of OS/2“. Although very interesting, unfortunately the article to a significant extent engages in what can best be called fantasy history, which causes the text … Continue reading →

Posted in IBM, Microsoft, OS/2 | 51 Comments