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Technology, Performance and Optimization

This site utilizes our highly optimized JS-DOS library for enhanced performance

Supports stereo output at a 44.1 kHz sample rate. Resolved audio popping and crackling issues, significantly reducing audio latency.
Supports 3Dfx Voodoo 3D hardware acceleration, resolution upscaling and anisotropic filtering.
Gamepad support.
Full support is provided for both Roland MT-32 and General MIDI. For General MIDI, you can choose from a range of soundfonts with varying levels of quality. By default, games are configured to prioritize General MIDI if both are supported.
The FPU subsystem has undergone a complete overhaul, enabling full compatibility and optimal performance for games employing specialized instructions.
Screen latency has been reduced by over 50%, resulting in significantly improved responsiveness.
CD swapping functionality and support for compressed CD audio formats.
Extensive code optimization has been implemented, resulting in a performance improvement of approximately 5%-10% in certain games compared to the original library.

Despite the aforementioned optimizations, running games in the browser still necessitates a CPU with robust single-core performance.
During the rapid advancement of CPU technology in the 1990s, processor performance saw significant improvements. For instance, games from 1995 had considerably different CPU requirements compared to those from 1997.
If a game fails to run smoothly, we recommend lowering the resolution and graphic quality settings through the in-game options.
You can run the benchmark to estimate your CPU performance when running legacy games in the browser.

Gameplay and Menu Functionality

Upon launching a game for the first time, the required game and system images will need to be downloaded. If it is a full CD version, the corresponding CD image will also be downloaded and extracted.
All disk or system images will be cached and will not need to be re-downloaded. You can manage cache settings through the settings page.

Once the game has started, additional functions can be accessed from the control menu at the top.
CD Swapping. For multi-CD games, you can select the appropriate CD when prompted to change discs. Once selected, the corresponding CD image will be downloaded and unpacked as needed.
Pause or resume the gameplay.
Mute or unmute.
Save to cloud. Available to Gold members only.
Save to browser storage.
Save and download the save file.
Note: The save function only preserves disk changes within the emulation environment. You must first use the in-game save function, then utilize the save options in the control menu to save disk changes. Otherwise, your game progress will be lost upon closing the browser.
Windows Game Note: Due to the nature of the Windows operating system, we highly recommend using the save function after closing the game and ensuring the OS has completely shut down to prevent potential disk corruption.

Browser Compatibility

For optimal compatibility, it is recommended to use the latest version of Chrome.
Browsers based on the Chromium engine, such as Edge, are also expected to be supported.
Firefox is not supported for Windows gaming due to limitations related to the maximum size of a single IDB item.
Safari is not recommended due to its limited support for modern browser standards, which results in a lack of support for 3D acceleration and instability with WASM.