Macintosh File System (MFS) is a

volume Volume is a measure of regions in three-dimensional space. It is often quantified numerically using SI derived units (such as the cubic metre and litre) or by various imperial or US customary units (such as the gallon, quart, cubic inch) ...

format (or disk file system) created by

Apple Computer Apple Inc. is an American multinational corporation and technology company headquartered in Cupertino, California, in Silicon Valley. It is best known for its consumer electronics, software, and services. Founded in 1976 as Apple Computer Co ...

for storing files on 400K

floppy disk A floppy disk or floppy diskette (casually referred to as a floppy, a diskette, or a disk) is a type of disk storage composed of a thin and flexible disk of a magnetic storage medium in a square or nearly square plastic enclosure lined with a ...

s. MFS was introduced with the original

Apple Macintosh Mac is a brand of personal computers designed and marketed by Apple Inc., Apple since 1984. The name is short for Macintosh (its official name until 1999), a reference to the McIntosh (apple), McIntosh apple. The current product lineup inclu ...

computer in January 1984. MFS is notable both for introducing

resource fork A resource fork is a fork of a file on Apple's classic Mac OS operating system that is used to store structured data. It is one of the two forks of a file, along with the data fork, which stores data that the operating system treats as unstruct ...

s to allow storage of structured data, and for storing

metadata Metadata (or metainformation) is "data that provides information about other data", but not the content of the data itself, such as the text of a message or the image itself. There are many distinct types of metadata, including: * Descriptive ...

needed to support the

graphical user interface A graphical user interface, or GUI, is a form of user interface that allows user (computing), users to human–computer interaction, interact with electronic devices through Graphics, graphical icon (computing), icons and visual indicators such ...

of the

classic Mac OS Mac OS (originally System Software; retronym: Classic Mac OS) is the series of operating systems developed for the Mac (computer), Macintosh family of personal computers by Apple Computer, Inc. from 1984 to 2001, starting with System 1 and end ...

. MFS allows file names to be up to 255 characters in length, although Finder does not allow users to create names longer than 63 characters (31 characters in later versions). MFS is called a flat file system because it does not support a hierarchy of directories. Folders exist as a concept on the original MFS-based Macintosh, but work completely differently from the way they do on modern systems. They are visible in Finder windows, but not in the open and save

dialog box In computing, a dialog box (also simply dialog) is a graphical control element in the form of a small window that communicates information to the user and prompts them for a response. Dialog boxes are classified as " modal" or "modeless", dep ...

es. There is always one empty folder on the volume, and if it is altered in any way (such as by adding or renaming files), a new Empty Folder appears, thus providing a way to create new folders. MFS stores all of the file and directory listing information in a single file. The Finder creates the illusion of folders, by storing all files as pairs of directory handles and file handles. To display the contents of a particular folder, MFS scans the directory for all files in that handle. There is no need to find a separate file containing the directory listing. The Macintosh File System does not support volumes over 20 MB in size, or about 1,400 files. While this is small by today's standards, at the time it seemed very expansive when compared to the

Macintosh Mac is a brand of personal computers designed and marketed by Apple Inc., Apple since 1984. The name is short for Macintosh (its official name until 1999), a reference to the McIntosh (apple), McIntosh apple. The current product lineup inclu ...

's 400 KB floppy drive. Apple introduced

Hierarchical File System In computing, a hierarchical file system is a file system that uses directories to organize files into a tree structure. In a hierarchical file system, ''directories'' contain information about both files and other directories, called ''sub ...

as a replacement for MFS in September 1985. In Mac OS 7.6.1, Apple removed support for writing to MFS volumes “as such writes often resulted in errors or system hangs”, and in Mac OS 8.0 support for MFS volumes was removed altogether. Although

macOS macOS, previously OS X and originally Mac OS X, is a Unix, Unix-based operating system developed and marketed by Apple Inc., Apple since 2001. It is the current operating system for Apple's Mac (computer), Mac computers. With ...

(formerly Mac OS X) has no built-in support for MFS, an example VFS plug-in from Apple called MFSLives provides read-only access to MFS volumes.

Citations

General and cited references

External links

Apple Tech Article 9502
��MFS volume support in Mac OS 7.x

��HFS used in Macs with 128K ROMs different from MFS used in Macs with 64K ROMs

—limitation due to MFS on an external 400K floppy drive disk {{File systems Apple Inc. file systems Disk file systems Macintosh operating systems

See also

Citations

General and cited references

External links