DOS VESA Video Modes COM Dumper Tool

This tool runs in real mode DOS and produces two files containing VESA video modes data:

• A readable .TXT file for debugging purposes
• A binary .BIN file that contains detailed information about all available video modes

How to use

1. Copy the bin/VESAINFO.COM file from the bin folder into your application's bin directory.

2. In your application, run the tool using:

int result = system("VESAINFO.COM");

3. If the result is 0, the tool ran successfully and will create a file named VESAINFO.BIN

Format

VESAINFO.BIN is binary file with the following structure:

• MainHeader
• VESAMainInfo
• Multiple:
  • ModeHeader
  • VESAModeInfo
• Ending with ModeHeader where mode set to 0

The structure definitions can be found in this repository at: src/headers.h

Notes on Data

VESAMainInfo contains general VESA data including the VESA version. Version of 0x0200 or higher is required for linear framebuffer support.

Each ModeHeader contains the video mode number (e.g., 0x101, 0x4101, etc.)

Each VESAModeInfo contains parameters such as resolution, color depth, mode attributes, and memory layout.

Why it's needed

Calling BIOS interrupts (like VESA functions) from protected mode can be unstable or unsupported on some systems — especially under Windows 98 or certain DOS extenders.

This tool queries video modes information in real mode. It provides much higher compatability.

Tested systems

• DosBox 0.74
• Lenovo T42 Windows 98 SE
• Lenovo T42 Dos 7