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OSdata.com: logical layer 

OSdata.com

Logical Layer of an Operating System

    The Logical Level of the operating system provides high level functions, such as file management, internet and networking facilities, etc.

    The file system and the shell program (especially graphic shell programs) are the primary ways that the typical computer user experiences a computer. Many people think of an operating system as just these two elements.

    The file system provides a logical manner for programs to access files. The actual data is stored as binary bits on a storage media (magnetic, optical, etc.), often with special information for error correction and other internal purposes. Data is usually stored in blocks — and there are numerous ways blocks can be organized on the physical medium. Rather than having each program directly access the hardware and correctly interpret the bit patterns of the physical media, operating systems provide a logical file system. Programs (including all but the lowest level of the operating system) reference specific files by file names or various kinds of access numbers and use standardized file system APIs for things such as read, write, append, etc.

    Some operating systems (such as UNIX) treat all files as a stream of bits or a stream of bytes. Other operating systems provide more sophisticated interpretations of files. Most mainframe operating systems offer both a stream of bytes approach and various indexed approaches. Some operating systems provide data base like access to specific records and data stored in files, while other operating systems leave this capability to specialized data base management software. Some operating systems provide services for certain kinds of files (such as multimedia interpretations of music and video, word processing interpretations of text documents, etc.). The Macintosh provides a Resource Manager, which separates executable code from supporting resources, allowing developers to add new translations and other internationalization without having to recompile the underlying program.

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File System

file system summaries

     HFS+: Apple’s new high performance file system (replaced HFS in System 8.1); native in Rhapsody, Mac OS X, Mac OS X Server, and Macintosh System 8.1-8.5; operating systems that can handle HFS+: Mac OS X (NRWF), Mac OS X Server (NRWF), Macintosh System 8.1-8.5 (RWF), Rhapsody (NRWF)

     HFS: Apple’s Heirarchial File System (replaced MFS in System 4); native in Macintosh System 4.0-8.0; operating systems that can handle HFS: AmigaOS (RW), BeOS (RW), FreeBSD (rw), IRIX (RW), LINUX (rw), Mac OS X (DRWF), Mac OS X Server (DRWF), Macintosh (RWF), OS/2 (rw), Pyramid (RW), Rhapsody (DRWF), Windows 2000 (rw) (“third-party support”)e115 (NOTE: This is the first HFS that appears in the chart)

     MFS: Apple’s Macintosh File System (original Macintosh file system); native in Macintosh System 1-3; operating systems that can handle MFS: Macintosh System 1.0-8.1 (RWF)

    Pro: Apple’s ProDOS File System (used in the Apple II); operating systems that can handle MFS: Macintosh (RWF)

     NTFS: Windows NT’s native file systeme17; two opinions: “NT’s NTFS is a slight variation/copy of HPFS which some dubious ‘improvements’.”e22; “NTFS is far removed from HPFS (it offers a superset of features, but doesn’t use an i-node type structure, which HPFS does; it’s also faster, more efficient with large disks, has better security features”e115; operating systems that can handle NTFS: LINUX (R), OS/2 (r), Pyramid (RW), Windows 2000 (NRWF), Windows NT (NRWF)

     FAT32: Windows 95 OSR2’s native 32-bit file system (kernel patch)e17; operating systems that can handle FAT32: AmigaOS (RW), BeOS (RW), FreeBSD (RW), LINUX (RW), Mac OS X (RW), Macintosh (RW), OS/2 (rw), Rhapsody (RW), Windows 2000 (RWF), Windows 98 (NRWF), Windows 95 (NRWF)

     VFAT: Windows 95’s native file system (long file names)e17; operating systems that can handle VFAT: AmigaOS (RW), BeOS (RW), FreeBSD (RW), LINUX (RW), Mac OS X (RW), Macintosh (RW), OS/2 (rw), Rhapsody (RW), Windows 2000 (RWF), Windows 98 (RW), Windows 95 (NRWF)

    FAT: MS-DOS’s native file systeme17; operating systems that can handle FAT: AmigaOS (RWF), BeOS (RW), Digital UNIX (rw), FreeBSD (RW), HP-UX (RW), IRIX (RW), LINUX (RWF), Mac OS X (RWF), Macintosh (RWF), MS-DOS (NRWF), OpenVMS (rw), OS/2 (DRWF), Pyramid (RW), Rhapsody (RWF), Solaris (RW), ULTRIX (rw), VMS (rw), Windows 2000 (RWF), Windows NT (RWF), Windows 98 (RW), Windows 95 (RW), Windows 3.1 (NRWF)

    UFS: UNIX’s native UNIX File System for Solaris, Sun-OS, FreeBSD, NetBSD, OpenBSD, NeXTSTEP, and OpenSTEPe21; operating systems that can handle UFS: Digital UNIX (RW), FreeBSD (RW), HP-UX (RW), Mac OS X (NRFW), Mac OS X Server (NRFW), NetBSD (NRWF), NeXT (NRWF), NeXTSTEP (NRWF), OpenBSD (NRWF), OpenSTEP (NRWF), Pyramid (RW), Rhapsody (RWF), Solaris (NRWF), Sun-OS (NRWF), ULTRIX (RW)

    isofs: ISO 9660 (for CD-ROMs)e17; this is a read-only format, for obvious reasons; there are different levels of ISO 9660: Level 1 is universal, Level 2 allows more characters for file naming at the expense of cutting out some operating systems; operating systems that can handle ISO 9660: AIX (R), AmigaOS (R), BeOS (Rw), Digital UNIX (R), FreeBSD (R), HP-UX (Rw1), IRIX (Rw), LINUX (Rw), Mac OS X (Rw), Macintosh (Rw), OpenVMS (R), Rhapsody (Rw), ULTRIX (R), VMS (R), Windows 2000 (Rw), Windows 98 (Rw), Windows 95 (Rw)

     Hybrid: Hybrid is a special format that appears on a Macintosh as a Macintosh HFS formatted disk and on all other operating systems (that can read CD-ROMs) as an ISO 9660 disk. A Hybrid disk can only be made on the Macintosh. (NOTE: does not have an entry in the chart below)

    rock: RockRidge extension to ISO 9660 (for CD-ROMs)e41; operating systems that can read RockRidge: AmigaOS (R), HP-UX (r), Windows 2000 (R) (“but symlinks and certain other features won’t work”e115), Windows 98 (R) (“but symlinks and certain other features won’t work”e115)

    jol: Microsoft’s Joliet extension to ISO 9660 (for CD-ROMs)e41

    CD-i: CD-i (interactive), a format for multi-media CD-ROMs; operating systems that can read CD-i: AmigaOS (R), Mac OS X (Rw), Macintosh (Rw), Windows 2000 (R)

    VCD: Video CD, a format for storing video on CD-ROMs; operating systems that can read VCD: Mac OS X (Rw), Macintosh (Rw), Windows 2000 (R)

    ECD: Enhanced CD, a format that plays as both an ordinary audio CD and as a multi-media CD-ROM; operating systems that can read ECD: Mac OS X (Rw), Macintosh (Rw), Windows 2000 (R), Windows 98 (R), Windows 95 (R)

    PD: PhotoDisk, Kodak’s format for storing photographs on a CD-ROM; operating systems that can read PhotoDisks: AmigaOS (R), Mac OS X (Rw), Macintosh (Rw), Windows 2000 (R), Windows 98 (R)

    CD: Audio CD, the original audio only CD format; operating systems that can play audio CDs: AmigaOS (R), Mac OS X (Rw), Macintosh (Rw), Windows 2000 (R), Windows 98 (Rw), Windows 95 (Rw)

    DVD-Video: Digital Video Disk - MPEG-2 Video (2 hours 15 minutes); operating systems that can read DVD-Video: Mac OS X (Rw), Macintosh (Rw), Windows 2000 (R), Windows 98 (R)

    DVD-ROM: Digital Video Disk, a high capacity (4.75 GB per side) replacement for CDs and CD-ROMs; operating systems that can read DVD-ROM: Mac OS X (Rw), Macintosh (Rw), Windows 2000 (R), Windows 98 (R)

    DVD-R: Digital Video Disk, write once storage (3.95 GB per side); operating systems that can read DVD-R: Mac OS X (Rw), Macintosh (RW)

    DVD-R/W: Digital Video Disk, Pioneer’s rewritable format (3.95 GB per side); operating systems that can read DVD-R/W: Mac OS X (Rw), Macintosh (RW)

    DVD-RAM: Digital Video Disk, industry proposed rewritable format (2.6 GB per side); operating systems that can read DVD-RAM: Mac OS X (Rw), Macintosh (RW)

    DVD+RW: Digital Video Disk, Sony and Philips proposed rewritable format (3 GB per side); operating systems that can read DVD+RW:

    MMVF: Multimedia Video File, NEC’s proposed DVD format (5.6 GB per side); operating systems that can read MMVF:

     ext2fs: LINUX’s native file system (replaces extfs)e17; operating systems that can handle ext2fs: FreeBSD (RW), LINUX (NRWF), OS/2 (rw), Windows 2000 (rw) (“poor third-party support”)e115

     extfs: LINUX’s original Extended File System (replaced by ext2fs)e30; operating systems that can handle ext2fs: LINUX (RWF), OS/2 (rw)

    BFFS: BSD Fast File Systeme35; operating systems that can handle BFFS: AmigaOS (rw), BSDi (RW), HP-UX (RW)

    AFS: Transarc’s Andrew File Systeme40; operating systems that can handle AFS: AIX (rw), HP-UX (rw) (NOTE: This is the first AFS that appears in the chart)

     HPFS-2: OS/2’s native High Performance File System (OS/2 version 2.1 or later)e22; operating systems that can handle HPFS-2: LINUX (R), OS/2 (NRWF)

     HPFS: OS/2’s native High Performance File Systeme22; operating systems that can handle HPFS: LINUX (R), OS/2 (NRWF), Pyramid (RW)

     FFS: Fast File System, AmigaOS’s native file system (Kickstart 1.3 and later)e27; operating systems that can handle FFS: AmigaOS (NRWF), LINUX (RW)

     OFS: AmigaOS’s original Old File Systeme34; operating systems that can handle OFS: AmigaOS (RWF)

     afs/afs2: AmigaOS’s high stability Ami-Fail-Safe file systeme27; operating systems that can handle afs: AmigaOS (rwF) (NOTE: This is the second afs that appears in the chart)

     MuFS: AmigaOS’s MultiUser File Systeme27; operating systems that can handle MuFS: AmigaOS (rwF)

     DCFS: AmigaOS’s Directory Caching File Systeme34; operating systems that can handle DCFS: AmigaOS (rwF)

     SFS: AmigaOS’s freeware Smart File Systeme35; operating systems that can handle SFS: AmigaOS (rwF)

     ODS-5: VMS’s most recent On Disk Structure file systeme39; operating systems that can handle ODS-5: OpenVMS (NRWF)

     ODS-2: VMS’s native On Disk Structure file systeme36; operating systems that can handle ODS-2: OpenVMS (NRWF), VMS (NRWF)

     ODS-1: PDP-11’s native file systeme19; operating systems that can handle ODS-1: OpenVMS (RWF), VMS (RWF)

     XFS: SGI IRIX’s new native file system (IRIX 6.2 and later)e24; operating systems that can handle XFS: AmigaOS (RW), IRIX (NRWF)

     EFS: SGI IRIX’s original native file systeme24; operating systems that can handle EFS: AmigaOS (RW), IRIX (RWF)

     befs: BeOS’s native 64-bit journaled file systeme29; operating systems that can handle befs: BeOS (NRWF)

    coda: successor to NFSe21; operating systems that can handle coda: FreeBSD (RW), LINUX (RW)

    NFS: Network File System; replaced by codae21; operating systems that can handle NFS: AIX (RW), AmigaOS (rw), BeOS (rw), BSDi (RW), Digital UNIX (RW), FreeBSD (RW), HP-UX (RW), IRIX (RW), LINUX (RW), NetWare (RW), OpenVMS (rw), OS/2 (rw), ULTRIX (RW), VMS (rw), Windows 2000 (rw) “with a Microsoft but non-bundled product called ‘Services for UNIX’ Windows 2000 can also act as both an NFS Client and Server”e115

    DFS: OSF DCE’s Distributed filesystem; operating systems that can handle AFS: AIX (rw)

     VxFS: HP-UX’s Veritas File System; native in recent versions of HP-UXe40; operating systems that can handle VxFS: HP-UX (NRWF)

     JFS: HP-UX’s Journaled FileSysteme67 for recent versions of HP-UXe20; not to be confused with AIX’s jfs (lower case letters); HP-UX: “JFS is brand new at 10.xx and has gone through some painful design changes. It still does not handle ACL’s and has a few other limitations. Starting with 10.20, the default Instant Ignition found on new systems uses HFS for /stand (absolutely required or the system won’t boot) and JFS for the root volume.”e42; operating systems that can handle JFS: HP-UX (NRWF)

     hfs: HP-UX’s Hi Performance FileSystem; native in older versions of HP-UXe20; “HFS has been the native file system since the mid 80s.”e42; operating systems that can handle hfs: HP-UX (NRWF) (NOTE: This is the second hfs that appears in the chart)

     LIF: HP-UX’s original file system; “The LIF filesystem is used by the processor ROMs and found in the bootup sectors at the beginning of the disk”e42; operating systems that can handle hfs: HP-UX (NRW)

    jfs: Journaled File System, AIX’s native file system, not to be confused with HP-UX’s Journaled FileSystem (JFS, capital letters), AutoFS: is “a convenient mechanism for mounting”, operating systems that can handle jfs: AIX (NRWF), OS/2 (RWF)

    CacheFS: operating systems that can handle CacheFS: AIX (RW)

    Minix: an obsolete file system that was the original native file system for LINUX e21; native file system for Minix; operating systems that can handle Minix: AmigaOS (rw), LINUX (RW), Minix (NRWF)

    sysvfs: UNIX System V; SCO, Xenix, Coherente21; operating systems that can handle sysvfs: FreeBSD (rw), LINUX (R), SCO (NRWF)

    Xenix: operating systems that can handle Xenix: FreeBSD (rw), LINUX (RW)

    UMSDOS: a special filesystem which allows LINUX to be installed on a MS-DOS filesysteme18; operating systems that can handle UMSDOS: LINUX (RW)

    xiafs: operating systems that can handle xiafs: LINUX (RW)

    CIFS: a superset of SMB; the security problems of SMB are not solved with CIFS; operating systems that can handle CIFS: Windows 2000 (RW), Windows NT (RW)

    SMB: Server Message Block; NetBIOS networkinge20; originally used for print and file sharing on Windows, most UNIXs share file and print services with Windows systems through an open source program called SAMBA; SMB has great security risks (see SMB and firewalls); operating systems that can handle SMB: AIX (rw), BSDi (rw), Digital UNIX (rw), FreeBSD (rw), HP-UX (rw), IRIX (rw), LINUX (RW), Macintosh (RW), MS-DOS (RW), NetBSD (rw), NeXT (rw), OpenBSD (rw), OpenVMS (rw), PC-DOS-2000 (RW), Rhapsody (rw), SCO OpenServer (rw), SCO UnixWare (rw), Solaris (rw), Sun-OS (rw), Tru64 Unix (rw), ULTRIX (rw), VMS (rw), Windows 2000 (RW), Windows NT (RW), Windows 98 (RW), Windows 95 (RW), Windows 3.11 (RW), PC-DOS (RW), MS-DOS (RW)

    adfs: Acorn’s native file systeme21; operating systems that can handle adfs: AmigaOS (rw), LINUX (R)

    TVFS: Toronto Virtual File Systeme31; operating systems that can handle TVFS: OS/2 (rw)

    CPM: operating systems that can handle CPM: AmigaOS (r)

    1541: Commodore c64; operating systems that can handle 1541: AmigaOS (r), LINUX (r)

    PFS/PFS2: Professional File System (shareware predecessor of Amiga’s AFS and AFS2 e35, operating systems that can handle PFS2: AmigaOS (rw)

    QL: Sinclair’s native file systeme35; operating systems that can handle QL: AmigaOS (r)

    ROMFS: a read-only file system for use in ROMse90; operating systems that can handle ROMFS: LINUX (r)

     rxfs: a proprietary implementation of vxfse96; operating systems that can handle rxfs: Pyramid (RWF)

    NSS: NetWare’s new file systeme97; operating systems that can handle NSS: NetWare (RWF)

    classic: NetWare’s original file systeme97; operating systems that can handle NetWare classic: NetWare (RWF)

    See the chart on file systems used by various operating systems.

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    Last Updated: November 19, 2006

    Created: June 4, 1998

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