Author Archives: Michal Necasek

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 | 10 Comments

AI Responses May Include Mistakes

Posted on May 20, 2025 by Michal Necasek

The other day I wanted to look up a specific IBM PS/2 model, a circa 1992 PS/2 Server system. So I punched the model into Google, and got this: That did not look quite right, since the machine I was … Continue reading →

Posted in IBM, PS/2 | 26 Comments

Compaq EXTDISK.SYS

Posted on April 16, 2025 by Michal Necasek

This is a follow-up to a previous post about the curious driver in Microsoft OS/2 1.21. After initially writing the article, additional information came to light, explaining why the code was there. In summer 1988, Compaq released the Deskpro 386/25, … Continue reading →

Posted in Bugs, Compaq, DOS, PC history, Storage | 32 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 | 43 Comments

ESDI Adventures

Posted on March 19, 2025 by Michal Necasek

At long last, I got hold of a decently well functioning ESDI drive. From my earlier adventures, I had a WD1007V-SE2 controller, as well as an older WD1007A. The WD1007A (Compaq branded) used to live in a Hyundai 286 machine … Continue reading →

Posted in ESDI, PC hardware, PC history, Seagate | 34 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

Learn Something Old Every Day, Part XIV: read() Return Value May Surprise

Posted on February 25, 2025 by Michal Necasek

Last week I amused myself by porting some source code from Watcom C to Microsoft C. In general that is not difficult, because Watcom C was intended to achieve a high degree of compatibility with Microsoft’s C dialect. Yet one … Continue reading →

Posted in C, Development | 11 Comments

Learn Something Old Every Day, Part XIII: InDOS Is Not Enough

Posted on February 12, 2025 by Michal Necasek

The other day I spent a while trying to understand the purpose of a rather strange looking piece of code inside Borland’s THELP.COM utility shipped with Turbo Pascal 6.0 (THELP.COM was misbehaving under emulated DOS). The THELP utility performs the … Continue reading →

Posted in DOS, PC history, Undocumented | 14 Comments

Minor 387 Documentation Mystery

Posted on January 10, 2025 by Michal Necasek

So here I am, writing a bit of test code to figure out the behavior of x87 FPUs with regard to saving and loading the FPU state (FSTENV/FLDENV and FSAVE/FRSTOR instructions in different modes and formats). The original real-mode only … Continue reading →

Posted in Documentation, Intel, x87 | 9 Comments

The Other Three

Posted on January 2, 2025 by Michal Necasek

A previous blog post explored the semi-mysterious yet sometimes highly useful DOS APPEND command. Now it’s time to look at its relatives: ASSIGN, JOIN, and SUBST. ASSIGN ASSIGN is the oldest of the bunch. It was written by IBM and … Continue reading →

Posted in DOS, IBM, PC history | 13 Comments