CS0 File

What are CS0 files and how to open them

Are you having problems opening a CS0 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 CS0 files.

What is a CS0 file?

A .CS0 file is a Callus Savestate file.

Callus savestate files capture the exact running state of the Callus emulator made by Bloodlust Software, which emulates the Capcom Play System 1 arcade hardware. They store all emulator memory, CPU and sound chip states so that a game can be paused and later resumed from the exact same point, including volatile state like registers, RAM, video and audio buffers.

These files are created by the Save State feature in Callus. When loading one, the emulator restores the CPS-1 system to exactly how it was when the savestate was created, bypassing normal game save points or pause menus. Because these files embed hardware-level state, a savestate generated under one version of Callus may not work under another if the emulator's internal layout or version changes.

A Callus savestate file begins with a fixed identification signature: the ASCII "CST" followed by a null byte, stored at offset zero.

How to open CS0 files

Important: Different programs may use files with the CS0 file extension for different purposes, so unless you are sure which format your CS0 file is, you may need to try a few different programs.

While we have not verified the apps ourselves yet, our users have suggested two different CS0 openers which you will find listed below.

Last updated: September 19, 2026

Various apps that use files with this extension

These apps are known to open certain types of CS0 files. Remember, different programs may use CS0 files for different purposes, so you may need to try out a few of them to be able to open your specific file.

Help us help others

File.org helps thousands of users every day, and we would love to hear from you if you have additional information about CS0 file formats, example files, or compatible programs. Please use the links below or email us at submit@file.org to discuss further.