File System In Mac

MFS
Structures
Developer(s)	Apple Computer
Full name	Macintosh File System
Introduced	January 24, 1984; 36 years ago with System 1
Partition identifier	Apple_MFS (Apple Partition Map)
Directory contents	Table
File allocation	Linked list
Bad blocks	No
Limits
Max. volume size	20 MiB
Max. file size	20 MiB
Max. number of files	4094
Max. filename length	255 characters
Allowed characters in filenames	Any Apple codepage (such as MacRoman) character but ':'
Features
Dates recorded	Creation, modification
Date range	January 1, 1904 - February 6, 2040
Date resolution	1s
Forks	Only 2 (data and resource)
Attributes	version, locked, type, creator, Finder window, location in Finder window, Finder flags
File system permissions	No
Transparent compression	No
Transparent encryption	No
Other
Supported operating systems	System 1 — OS 7.6 (Write), Mac OS 8.0 (Read), macOS (Read with MFSLives)

Macintosh File System (MFS) is a volume format (or disk file system) created by Apple Computer for storing files on 400K floppy disks. MFS was introduced with the original Apple Macintosh computer in January 1984.

File system Creator Year of introduction Original operating system; DECtape: DEC: 1964 PDP-6 Monitor OS/3x0 FS: IBM: 1964 OS/360: Level-D DEC: 1968 TOPS-10: George 3 ICT (later ICL) 1968 George 3: Version 6 Unix file system (V6FS) Bell Labs: 1972 Version 6 Unix: RT-11 file system DEC: 1973 RT-11: Disk Operating System GEC: 1973 Core Operating. The Mac OS X file system stores files within folders, also known as directories. The top, uppermost folder is known as the root directory. Folders located within (or beneath) the root directory are.

MFS is notable both for introducing resource forks to allow storage of structured data, and for storing metadata needed to support the graphical user interface of Mac OS. 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 boxes. 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's 400 KB floppy drive.

Apple introduced Hierarchical File System as a replacement for MFS in September 1985. In Mac OS 7.6.1, Apple removed support for writing to MFS volumes,^[1] and in Mac OS 8.0 support for MFS volumes was removed altogether. Although macOS has no built-in support for MFS, an example VFS plug-in from Apple called MFSLives provides read-only access to MFS volumes.

References[edit]

^'Technical Notes'. Developer.apple.com. Retrieved 2013-09-16.

Bibliography[edit]

Apple Computer, Inc. (1985). Inside Macintosh Volume II. New York: Addison-Wesley. ISBN0-201-17732-3.

External links[edit]

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)
Fred's Follies - HFS used in Macs with 128K ROMs different from MFS used in Macs with 64K ROMs
Q&A: Mac Plus - limitation due to MFS on an external 400K floppy drive disk
MFSLives - VFS read-only plug-in for MFS in macOS