Category Archives: Windows

VDS: Borne out of Necessity

Posted on October 5, 2023 by Michal Necasek

In July 1990, Microsoft released a specification for Virtual DMA Services, or VDS. This happened soon after the release of Windows 3.0, one of the first (though not the first) providers of VDS. The VDS specification was designed for writers … Continue reading →

Posted in 386, Documentation, Microsoft, PC history, Windows | 10 Comments

Windows 3.x VDDVGA

Posted on January 23, 2023 by Michal Necasek

While working on my Windows 3.x display driver, I ran into a vexing problem. In Windows 3.1 running in Enhanced 386 mode, I could start a DOS session and switch it to a window. But an attempt to set a … Continue reading →

Posted in 386, Development, Documentation, Graphics, PC history, Windows | 59 Comments

A House of Cards

Posted on December 30, 2022 by Michal Necasek

As one step in the development of the Windows 3.x/2.x display driver, I needed to replace a BIOS INT 10h call to set the video mode with a “native” mode set code going directly to the (virtual) hardware registers. One … Continue reading →

Posted in Bugs, Development, Microsoft, Windows | 49 Comments

Win16 Retro Development

Posted on December 20, 2022 by Michal Necasek

Several months ago I had a go at producing a high resolution 256-color driver for Windows 3.1. The effort was successful but is not yet complete. Along the way I re-learned many things I had forgotten, and learned several new … Continue reading →

Posted in Debugging, Development, Microsoft, Windows | 27 Comments

Antique Display Driving

Posted on July 29, 2022 by Michal Necasek

Here’s a preview of something I’ve been slowly working on, bit by bit: That screenshot surely looks a little funny. That’s because it is Windows 1.04 running with a heavily modified 256-color Windows 3.x display driver, using resources from a … Continue reading →

Posted in Development, Microsoft, Windows | 36 Comments

Learn Something Old Every Day, Part VI: Backward Buffer Overwrite

Posted on July 13, 2022 by Michal Necasek

A few days ago I spent far too much time debugging a largish piece of 16-bit Windows code written in assembler. I found a scenario where (fortunately fairly reproducibly) Windows crashed because the internal state of a DLL got corrupted. … Continue reading →

Posted in Bugs, Development, Windows | 24 Comments

FasterModeSwitch: Is It Really?

Posted on October 31, 2018 by Michal Necasek

Short answer: Yes. Before launching into the long answer, let’s recap what it even is. FasterModeSwitch is a SYSTEM.INI setting in Windows 3.1 which applies only to Standard (286) mode and can therefore be found in the [standard] section of … Continue reading →

Posted in 286, BIOS, Microsoft, Windows | 10 Comments

Didn’t Expect That to Work

Posted on October 22, 2018 by Michal Necasek

Once the ThinkPad T43p with a bad fan was in working shape again, I restored the preloaded software on it. Which meant Windows XP (this is a system from 2005). It didn’t take long for me to establish that XP … Continue reading →

Posted in ThinkPad, Windows | 22 Comments

Crazy World

Posted on October 17, 2018 by Michal Necasek

After I successfully upgraded two Windows 10 VMs to the 1809 release at the beginning of October, I tried to do the same with more VMs and an actual laptop this week. But I couldn’t, no update was offered. While … Continue reading →

Posted in Bugs, Microsoft, Random Thoughts, Windows | 9 Comments

Three Weeks

Posted on July 27, 2018 by Michal Necasek

I happen to own several old laptops, now about 10 years old, that had the misfortune of being delivered with a Windows Vista license and matching Windows Vista OEM installations on their recovery partitions/media. About a year ago, I noticed … Continue reading →

Posted in Bugs, Microsoft, Windows | 27 Comments