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URL Parameters

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Mike Daley edited this page Aug 2, 2026 · 1 revision

URL Parameters

The emulator can open with media already inserted, so a link can hand someone a running program rather than a set of instructions.

https://your-emulator/?disk=https://example.com/demo.dsk

Parameters

Parameter Target
disk Floppy drive 1
disk1 Floppy drive 1 (synonym for disk, so links read naturally)
disk2 Floppy drive 2
hd SmartPort device 1
hd1 SmartPort device 1 (synonym)
hd2 SmartPort device 2
name Display name for the loaded media

Multiple parameters can be combined:

?disk1=game-side-a.dsk&disk2=game-side-b.dsk&name=My%20Game

Accepted Images

Recognised extensions are .dsk, .do, .po, .nib, .woz, .2mg and .hdv.

Where a URL carries no usable filename -- which is common for share links from cloud storage -- the emulator sniffs the content, recognising the WOZ magic bytes and the exact 143,360-byte length of a standard .dsk.

URLs and Security

Only http and https URLs are accepted. A relative path is resolved against the page, so images hosted alongside the emulator work with a short link:

?disk=/demos/lode-runner.dsk

Fetches are made with credentials: "omit", so a link cannot use your cookies to reach something private, and each unit has a size ceiling: 8 MB per floppy and 64 MB per hard drive image. These are generous for real images but stop a link pulling down something unbounded.

The remote server must send permissive CORS headers for a cross-origin image to load; this is a browser rule the emulator cannot work around.

Loads Are Transient

Media loaded from a URL is deliberately not persisted:

  • it is not written to the browser's image storage,
  • it is not added to the recent-images list,
  • autosave is suspended for the session.

The reasoning is that a link should not quietly overwrite the disk you had in the drive. Your stored autosave preference is left untouched -- only this session's autosave is suspended.

Implementation Notes

Two modules, deliberately split so the tricky part is testable:

File Responsibility
src/js/utils/url-params.js Pure parsing and URL validation. Unit-tested in tests/js/utils/url-params.test.js.
src/js/disk-manager/url-media-loader.js Fetching (size-capped, credential-less) and insertion.

main.js parses the URL before DiskManager.init() and HardDriveManager.init(), populating urlOwnedDrives and urlOwnedDevices. Those managers use the lists to skip restoring a persisted image into a unit that a link is about to claim -- otherwise the two loads race, and which image you end up with depends on timing.

See Also

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