Macintosh File System (MFS) is a

volume Volume is a measure of occupied 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). The de ...

format (or disk

file system In computing, file system or filesystem (often abbreviated to fs) is a method and data structure that the operating system uses to control how data is stored and retrieved. Without a file system, data placed in a storage medium would be one larg ...

) created by

Apple Computer Apple Inc. is an American multinational technology company headquartered in Cupertino, California, United States. Apple is the largest technology company by revenue (totaling in 2021) and, as of June 2022, is the world's biggest company b ...

for storing files on 400K

floppy disk A floppy disk or floppy diskette (casually referred to as a floppy, or a diskette) is an obsolescent 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 w ...

s. MFS was introduced with the original

Apple Macintosh The Mac (known as Macintosh until 1999) is a family of personal computers designed and marketed by Apple Inc. Macs are known for their ease of use and minimalist designs, and are popular among students, creative professionals, and software en ...

computer in January 1984. MFS is notable both for introducing

resource fork The resource fork is a fork (file system), fork or section of a computer file, file on Apple Inc., Apple's classic Mac OS operating system, which was also carried over to the modern macOS for compatibility, used to store structured data along with t ...

s to allow storage of structured data, and for storing

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

needed to support the

graphical user interface The GUI ( "UI" by itself is still usually pronounced . or ), graphical user interface, is a form of user interface that allows users to interact with electronic devices through graphical icons and audio indicator such as primary notation, inste ...

of the

classic Mac OS Mac OS (originally System Software; retronym: Classic Mac OS) is the series of operating systems developed for the Macintosh family of personal computers by Apple Computer from 1984 to 2001, starting with System 1 and ending with Mac OS 9. The ...

. MFS allows file names to be up to 255

character Character or Characters may refer to: Arts, entertainment, and media Literature * ''Character'' (novel), a 1936 Dutch novel by Ferdinand Bordewijk * ''Characters'' (Theophrastus), a classical Greek set of character sketches attributed to The ...

s 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 In computing, file system or filesystem (often abbreviated to fs) is a method and data structure that the operating system uses to control how data is stored and retrieved. Without a file system, data placed in a storage medium would be one larg ...

because it does not support a hierarchy of

directories Directory may refer to: * Directory (computing), or folder, a file system structure in which to store computer files * Directory (OpenVMS command) * Directory service, a software application for organizing information about a computer network's u ...

. 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 The dialog box (also called dialogue box (non-U.S. English), message box or 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 ...

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 The Mac (known as Macintosh until 1999) is a family of personal computers designed and marketed by Apple Inc., Apple Inc. Macs are known for their ease of use and minimalist designs, and are popular among students, creative professionals, and ...

's 400 KB floppy drive. Apple introduced

Hierarchical File System Hierarchical File System (HFS) is a proprietary file system developed by Apple Inc. for use in computer systems running Mac OS. Originally designed for use on floppy and hard disks, it can also be found on read-only media such as CD-ROMs. HFS ...

as a replacement for MFS in September 1985. In Mac OS 7.6.1, Apple removed support for writing to MFS volumes, 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 operating system developed and marketed by Apple Inc. since 2001. It is the primary operating system for Apple's Mac computers. Within the market of desktop and lapt ...

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

References

Bibliography

External links

Apple Tech Article 9502
- MFS volume support in Mac OS 7.x
MacTech Volume 1, Issue 5: Disks
- organization of the standard Macintosh disk (April 1985)

- 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

- VFS read-only plug-in for MFS in macOS {{File systems Apple Inc. file systems Disk file systems Macintosh operating systems

See also

References

Bibliography

External links