C32 File

What are C32 files and how to open them

Are you having problems opening a C32 file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your C32 files.

What is a C32 file?

A .C32 file is a Syslinux COM32 Module file.

Syslinux COM32 Module files hold dynamically loadable boot modules designed for the Syslinux family of bootloaders. They are used to provide menu systems, diagnostic tools, or other utilities when booting a computer using BIOS. A COM32 module contains executable code that Syslinux reads and executes during the boot process to extend its functionality beyond simply loading an operating system kernel.

These modules are written specifically for Syslinux and are built according to the Comboot API. Syslinux generates or installs them as part of its module set, while the Syslinux core loader is responsible for loading a COM32 module from disk (usually in response to a configuration directive) and executing it. The module receives arguments (including the command line and API/helper pointers) from the loader, interacts with Syslinux helper facilities, performs its task (such as displaying a menu), and then hands control back to Syslinux when done.

Internally COM32 modules contain 32-bit protected-mode code linked to run at a fixed load address (commonly 0x101000), using flat segments for code, data, and stack. They begin with a "magic number" instruction (mov eax,21cd4cffh) to identify them, must avoid segment references, and expect certain register and pointer values for arguments such as command-line, INT helper, bounce buffer, far-call helper, etc. Syslinux sets up the execution environment with flat 32-bit segments and a stack pointer at the top of available memory before invoking the module.

How to open C32 files

Important: Different programs may use files with the C32 file extension for different purposes, so unless you are sure which format your C32 file is, you may need to try a few different programs.

While we have not verified the app ourselves yet, our users have suggested a single C32 opener which you will find listed below.

Last updated: August 25, 2026

Various apps that use files with this extension

These apps are known to open certain types of C32 files. Remember, different programs may use C32 files for different purposes, so you may need to try out a few of them to be able to open your specific file.

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