Category Archives: Microsoft

More than Two Hard Disks in DOS

Posted on July 22, 2025 by Michal Necasek

Investigating the rather odd behavior of the Microsoft OS/2 1.21 disk driver led me to Compaq and their EXTDISK.SYS driver. While experimenting with various setups, I realized that DOS versions older than 5.0 do not support more than two hard … Continue reading →

Posted in Bugs, Compaq, DOS, Microsoft, PC history | 82 Comments

1990 Networking: LAN Manager 2.0

Posted on July 16, 2025 by Michal Necasek

In 1990, Microsoft released LAN Manager (LM) 2.0, a member of a long line of Microsoft’s networking products that started with MS-NET circa 1984 and eventually morphed into Windows NT file sharing. LAN Manager 1.0 was released in 1988 as … Continue reading →

Posted in 3Com, LAN Manager, Microsoft, Networking, PC history | 10 Comments

1989 Networking: 3+Open LAN Manager 1.1

Posted on June 4, 2025 by Michal Necasek

The previously mentioned warez dump on archive.org contains a lot of little gems that would have been otherwise lost. One of those might be 3Com’s networking package from 1989, the 3+Open LAN Manager version 1.1. The software was released in … Continue reading →

Posted in 386MAX, 3Com, DOS, LAN Manager, Microsoft, Networking, OS/2 | 21 Comments

The Strange MS OS/2 1.21 Disk Driver

Posted on April 11, 2025 by Michal Necasek

Attempting to install Microsoft OS/2 1.21 will fail on many systems with the following scary looking error: Pressing Enter as directed shows the following more detailed error message: The initial boot phase, as well as the installation stage immediately before … Continue reading →

Posted in Bugs, Microsoft, OS/2, PC history | 44 Comments

Time Trouble

Posted on March 7, 2025 by Michal Necasek

Last Friday I had a moment of panic. While investigating why different run-time libraries might interpret file timestamps differently, I noticed that even Windows doesn’t always agree with itself. When was dos4gw.exe last modified, at 10:14 PM or 9:14 PM? … Continue reading →

Posted in Bugs, Development, Microsoft | 20 Comments

Programming NetBIOS on OS/2

Posted on October 23, 2024 by Michal Necasek

Recently I spent some time trying to understand a piece of networking code, and it turned out to be far more difficult than it should have been. The code in question is the NetBIOS interface of C-Kermit and was originally … Continue reading →

Posted in Development, Documentation, IBM, Microsoft, Novell, OS/2 | 25 Comments

More MS OS/2 2.0

Posted on June 30, 2024 by Michal Necasek

Over the last few weeks, two “new” pre-releases of OS/2 2.0 have been found in ancient warez archives. The first is OS/2 2.0 build 6.64, released in early April 1990: In general, this build is not substantially different from the … Continue reading →

Posted in IBM, Microsoft, OS/2, Pre-release | 6 Comments

Who Knew What When

Posted on June 28, 2024 by Michal Necasek

When Microsoft released the unique early beta build of Multitasking DOS 4, I quickly found out that it does not run in VirtualBox: This was a bit of a surprise, because the more-or-less released versions of Multitasking DOS 4 from … Continue reading →

Posted in 286, DOS, IBM, Microsoft, PC architecture, PC history, VirtualBox | 31 Comments

Learn Something Old Every Day, Part XII: Strange File Resizing on DOS

Posted on June 7, 2024 by Michal Necasek

Someone recently asked an interesting question: Why do Microsoft C and compatible DOS compilers have no truncate() and/or ftruncate() library functions? And how does one resize files on DOS? OK, that’s actually two questions. The first one is easy enough … Continue reading →

Posted in Computing History, CP/M, Development, Documentation, DOS, Microsoft | 29 Comments

The Future That Never Was

Posted on March 4, 2024 by Michal Necasek

Microsoft OS/2 2.0 SDK Pre-Release 2, June 1990 In 1990, the strategic PC operating system of Microsoft and IBM was not DOS, not Windows, but OS/2. The first 16-bit OS/2 was initially released in 1987 with a reduced feature set, … Continue reading →

Posted in 386, IBM, LAN Manager, Microsoft, OS/2, PC history, Pre-release | 76 Comments