DOSBox Direct

DOSBox Direct is an emulation backend based on DOSBox. You can create it with the following command:

const ci = await emulators.dosboxDirect(bundle);

The Direct version is universal and can work in a Node.js environment. Its main disadvantage is that it runs on the main browser thread, so it can freeze the app for some time and make it less responsive.

Accessing file system

In direct mode you can easily access the Emscripten module:

const ci = await emulators.dosboxDirect(bundle);
ci.transport.module // <-- emscripten module

The Emscripten module provides a low-level API to change the file system:

const ci = await emulators.dosboxDirect(bundle);
ci.transport.module.FS // <-- emscripten FS api

You can also rescan DOS devices:

const ci = await emulators.dosboxDirect(bundle);
ci.transport.module._rescanFilesystem();

Accessing memory

In direct mode you can dump the whole memory of DOS:

const ci = await emulators.dosboxDirect(bundle);
ci.transport.module._dumpMemory(copyDosMemory);
ci.transport.module.memoryContents // <-- now you can access contents using this var

If you need to copy the entire memory, pass true as argument. The memoryContents contains the following:

{
        "memBase": ...,
        "ip": ...,
        "flags": ...,
        "registers": {
            "ax": ...,
            "cx": ...,
            "dx": ...,
            "sp": ...,
            "bp": ...,
            "si": ...,
            "di": ...
        },
        "segments_values": {
            "es": ...,
            "cs": ...,
            "ss": ...,
            "ds": ...,
            "fs": ...,
            "gs": ...
        },
        "segments_physical": {
            "es": ...,
            "cs": ...,
            "ss": ...,
            "ds": ...,
            "fs": ...,
            "gs": ...
        },
        "numPages": ...,
        "memoryCopy": ...
}

Pausing execution

In direct mode, you can pause the DOSBox execution loop without pausing the Emscripten loop. This lets you pause and inspect the current memory, for instance.

const ci = await emulators.dosboxDirect(bundle);
ci.transport.module._pauseExecution(true);

The _pauseExecution function takes as its argument whether it should be paused or should resume. To resume once you have completed:

ci.transport.module._pauseExecution(false);

08 октября 2026