Mount a classic Mac disk image
Drop a Macintosh floppy or hard disk image in and it mounts on the desktop of an emulated Mac running System 7, exactly as if you had pushed the disk into the slot. DiskCopy 4.2 images, raw images and HFS volumes all work.
Everything happens in your browser. Your file is never uploaded anywhere.
The formats, and how to tell them apart
Raw images (.img, .dsk, .hfv) are a byte-for-byte copy of a disk with no wrapper at all. An 800K floppy image is exactly 819,200 bytes; a 1.4 MB image is 1,474,560. If your file is one of those sizes, it is almost certainly raw.
DiskCopy 4.2 images are the same data behind an 84-byte header carrying the volume name, the data and tag lengths and a checksum. Apple's DiskCopy was the standard way to distribute a floppy in the 1990s, so a great deal of preserved software is in this format. The loader strips the header for you.
NDIF and UDIF images (.img from the late 1990s, and .dmg) are compressed container formats and are a different problem — see the DMG page.
Self-mounting images (.smi) are a raw image with a small Macintosh application stapled to the front. They need a Mac to open, which is the one thing this page has.
Floppy or hard disk?
The emulated Mac cares. An image at one of the standard floppy sizes — 400K, 800K, 1.4 MB — is offered to the machine as a floppy and appears with a floppy icon. Anything larger is attached as a hard disk.
This mostly matters if the disk is a bootable system disk. A floppy with a System Folder can be started from; a hard disk image with a System Folder can be too, but the emulator has to be told to boot from it rather than from the disk it is already running.
If your image will not mount at all, the usual reasons are that it is an Apple II or ProDOS disk rather than a Macintosh one, that it is a compressed container rather than a raw image, or that it is damaged. HFS and the older MFS both mount fine; HFS+ works on System 8.1 and later, which is not what this page boots.
Where the disk lives afterwards
Only in this tab. The image is read by JavaScript from your own machine and handed to the emulator. It is not uploaded, and it is not kept: reload the page and you will need to drop it in again.
Anything you copy off the disk onto the emulated Mac's own hard drive does persist, in your browser's storage, until you clear site data.
Questions people ask
What is a .dsk file?
A raw disk image — a byte-for-byte copy of a floppy or hard disk, with no header. The Macintosh world uses .img, .dsk and .hfv fairly interchangeably for this.
What is DiskCopy 4.2?
Apple's disk imaging tool and its format: an 84-byte header with the volume name and checksums, followed by the raw disk data. It was the standard way Apple and most publishers distributed floppies.
Can I mount a .dmg here?
Older uncompressed .dmg files often work. Compressed UDIF images from Mac OS X do not mount on a classic Mac at all — the DMG page explains what to do instead.
Why does my image mount as read-only?
Some images are marked read-only inside the image itself, and some are damaged in a way the Mac notices. Copy what you need onto the emulated hard disk.
My image will not mount at all.
Check the size first — if it is not a multiple of 512 bytes it is probably not a raw image. It may be an Apple II disk, a compressed container, or truncated.
Can I boot from my own system disk?
Not from the loader page yet. That is on the list.