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Category Archives: Development
Hash Tables FTW
Over the last few weeks I did a bit of tinkering on a hobby software project. The code was written by two other people during the last several years and I finally managed to find some time to fix a … Continue reading
Posted in Development
4 Comments
Windows 3.x VDDVGA
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
Learn Something Old Every Day, Part VII: 8087 Intricacies
The other day I investigated a report that a C runtime library modification causes programs to hang on a classic IBM 5150 PC with no math coprocessor. The runtime originally contained two separate routines, one to detect the presence of … Continue reading
Posted in 8086/8088, Development, IBM, Intel, PC history, x87
10 Comments
A House of Cards
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
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
Undefined Isn’t Unpredictable
The other day I discovered that 32-bit FreeBSD 11.2 has strange trouble running in an emulated environment. Utilities like ping or top would just hang when trying to print floating-point numbers through printf(). The dtoa() library routine was getting stuck … Continue reading
Posted in AMD, Development, Documentation, Intel
22 Comments
Antique Display Driving
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
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
Windows 9x Video Minidriver Source Code
As promised, here is the source code for the Windows 9x VirtualBox display minidriver. For discussion of the source code, see the included readdev.txt file. The code was developed on a Windows 10 host system. For extra credit, I attempted … Continue reading
Posted in Development, Source code, VirtualBox, Watcom, Windows 95
18 Comments
Windows 9x Video Minidriver HD+
The OS/2 Museum has made available the first version of a display driver disk for Windows 9x running on VirtualBox. The driver uses a linear framebuffer and supports 8/16/24/32bpp modes with resolutions up to 1920×1200 pixels (see more below). The … Continue reading
Posted in Development, VirtualBox, Watcom, Windows 95
63 Comments