Post by johns.. » Sat, 07 Aug 1993 18:37:29

Archive-name: linux-faq/info-sheet
Last-modified: 13 Apr 93
Version: 3.02
                             Linux Information Sheet

        0.1 Introduction to Linux

        Linux is a completely free clone of the unix operating system
        which is available in both source code and binary form. It is
        copyrighted by Linus B. Torvalds (,
        and is freely redistributable under the terms of the Gnu Public
        License. Linux runs only on 386/486 machines with an ISA or EISA
        bus. MCA (IBM's proprietary bus) is not currently supported
        because there is little available documentation. However,
        support for MCA is being added at this time. Porting to other
        architectures is likely to be difficult, as the kernel makes
        extensive use of 386 memory management and task primitives.
        However, despite these difficulties, there are people
        successfully working on a port to the Amiga.

        Linux is still considered to be in beta testing. There are still
        bugs in the system, and since Linux develops rapidly (new
        versions come out about once every two weeks), new bugs creep
        up. However, these bugs are fixed quickly as well. Most versions
        are quite stable, and you can keep using those if they do what
        you need and you don't want to be on the bleeding edge. One site
        has had a computer running version 0.97 patchlevel 1 (dating
        from last summer) for over 136 days without an error or crash.
        (It would have been longer if the backhoe operator hadn't
        mistaken a main power transformer for a dumpster...)

        One thing to be aware of is that Linux is developed using an
        open and distributed model, instead of a closed and centralized
        model like much other software. This means that the current
        development version is always public (with up to a week or two's
        delay) so that anybody can use it. The result is that whenever a
        version with new functionality is released, it almost always
        contains bugs, but it also results in a very rapid development
        so that the bugs are found and corrected quickly, often in
        hours, as many people work to fix them. Furthermore, the bugs
        are generally discovered within hours of a kernel release,
        especially those which might endanger a user's data, so it is
        easy for an end-user to avoid these bugs.

        In contrast, the closed and centralized model means that there
        is only one person or team working on the project, and they only
        release software that they think is working well. Often this
        leads to long intervals between releases, long waiting for bug
        fixes, and slower development. Of course, the latest release of
        such software to the public is often of higher quality, but the
        development speed is generally much slower.

        As of May 26, 1993, the current version of Linux is 0.99
        patchlevel 10.

        0.2 Linux Features

         * multitasking: several programs running at once.

         * multiuser: several users on the same machine at once (and NO
           two-user licenses!).

         * runs in 386 protected mode.

         * has memory protection between processes, so that one program
           can't bring the whole system down.

         * demand loads executables: Linux only reads from disk those
           parts of a program that are actually used.

         * shared copy-on-write pages among executables. This means that
           multiple process can use the same memory to run in. When one
           tries to write to that memory, that page (4KB piece of
           memory) is copied somewhere else. Copy-on-write has two
           benefits: increasing speed and decreasing memory use.

         * virtual memory using paging (not swapping whole processes) to
           disk: to a separate partition or a file in the filesystem, or
           both, with the possibility of adding more swapping areas
           during runtime (yes, they're still called swapping areas). A
           total of 16 of these 16 MB swapping areas can be used at
           once, for a total 256 MB of useable swap space.

         * a unified memory pool for user programs and disk cache (so
           that all free memory can be used for caching, and the cache
           can be reduced when running large programs).

         * dynamically linked shared libraries (DLL's)(static libraries
           too, of course).

         * does core dumps for post-mortem analysis, allowing the use of
           a debugger on a program not only while it is running but also
           after it has crashed.

         * mostly compatible with POSIX, System V, and BSD at the source

         * all source code is available, including the whole kernel and
           all drivers, the development tools and all user programs;
           also, all of it is freely distributable.

         * POSIX job control.

         * pseudoterminals (pty's).

         * 387-emulation in the kernel so that programs don't need to do
           their own math emulation. Every computer running Linux
           appears to have a math coprocessor.

         * support for many national or customized keyboards, and it is
           fairly easy to add new ones.

         * multiple virtual consoles: several independent login sessions
           through the console, you switch by pressing a hot-key
           combination (not dependent on video hardware).

         * Supports several common filesystems, including minix-1 and
           Xenix, and has an advanced filesystem of its own, which
           offers filesystems of up to 4 TB, and names up to 255
           characters long.

         * transparent access to MS-DOS partitions (or OS/2 FAT
           partitions) via a special filesystem: you don't need any
           special commands to use the MS-DOS partition, it looks just
           like a normal Unix filesystem (except for funny restrictions
           on filenames, permissions, and so on). MS-DOS 6 compressed
           partitions do not work at this time.

         * CD-ROM filesystem which reads all standard formats of

         * TCP/IP networking, including ftp, telnet, NFS, etc.

        0.3 Hardware Issues

        0.3.1 Minimal configuration

        The following is probably the smallest possible configuration
        that Linux will work on: 386SX/16, 2 MB RAM, 1.44 MB or 1.2 MB
        floppy, any supported video card (+ keyboards, monitors, and so
        on of course). This should allow you to boot and test whether it
        works at all on the machine, but you won't be able to do
        anything useful.

        In order to do something, you will want some hard disk space as
        well, 5 to 10 MB should suffice for a very minimal setup (with
        only the most important commands and perhaps one or two small
        applications installed, like, say, a terminal program). This is
        still very, very limited, and very uncomfortable, as it doesn't
        leave enough room to do just about anything, unless your
        applications are quite limited. It's generally not recommended
        for anything but testing if things work, and of course to be
        able to brag about small resource requirements.

        0.3.2 Usable configuration

        If you are going to run computationally intensive programs, such
        as gcc, X, and TeX, you will probably want a faster processor
        than a 386SX/16, but even that should suffice if you are

        In practice, you need at least 4 MB of RAM if you don't use X,
        and 8 MB if you do. Also, if you want to have several users at a
        time, or run several large programs (compilations for example)
        at a time, you may want more than 4 MB of memory. It will still
        work with a smaller amount of memory (should work even with 2
        MB), but it will use virtual memory (using the hard drive as
        slow memory) and that will be so slow as to be unusable.

        The amount of hard disk you need depends on what software you
        want to install. The normal basic set of Unix utilities, shells,
        and administrative programs should be comfortable in less than
        10 MB, with a bit of room to spare for user files. For a more
        complete system, SLS reports that a full base system without X
        fits into 45 MB, with X into 70 MB (this is only binaries), and
        a complete distribution with everything takes 90 MB. Add the
        whatever space you want to reserve for user files to these

        Add more memory, more hard disk, a faster processor and other
        stuff depending on your needs, wishes and budget to go beyond
        the merely usable. In general, one big difference from DOS is
        that with Linux, adding memory makes a large difference, whereas
        with dos, extra memory doesn't make that much difference. This
        of course has something to do with DOS's 640KB limit.

        0.3.3 Supported hardware

        CPU: Anything that runs 386 protected mode programs (all models
        of 386s and 486s should work; 286s don't work, and never will).

        Architecture: ISA or EISA bus. MCA (mostly true blue PS/2's)
        does not work. Local bus works.

        RAM: Theoretically up to 1 GB. This has not been tested. Some
        people (including Linus) have noted that adding ram has slowed
        down their machine extremely without adding more cache at the
        same time, so if you add memory and find your machine slower,
        try adding more cache.

        Data storage: Generic AT drives (IDE, 16 bit HD controllers with
        MFM or RLL) are supported, as are SCSI hard disks and CD-ROMs,
        with a supported SCSI adaptor. Generic XT controllers (8 bit
        controllers with MFM or RLL) are now also supported. Supported
        SCSI adaptors: Adaptec 1542 (but not 1522), 1740 in extended
        (not 1542 compatible) mode, Seagate ST-01 and ST-02, Future
        Domain TMC-88x series (or any board based on the TMC950 chip)
        and TMC1660/1680, Ultrastor 14F, 24F and 34F, and Western
        Digital wd7000. SCSI and QIC-02 tapes are also supported. There
        is a device driver available for at least some QIC-02 tape
        drives, though it is not in the standard kernel.

        Video: VGA, EGA, CGA, or Hercules (and compatibles) work in text
        mode. For graphics and X, there is support for (at least) EGA,
        normal VGA, some super-VGA cards (most of the cards based on
        ET3000, ET4000, Paradise, and some Trident chipsets), some S3
        cards (not Diamond Stealth, because the manufacturer won't tell
        how to program it), 8514/A, and hercules. (Linux uses the
        Xfree86 X server, so that determines what cards are supported.)

        Other hardware: SoundBlaster, ProAudio Spectrum 16, AST Fourport
        cards (with 4 serial ports), several models of Boca serial
        boards, the Usenet Serial Card III, several flavours of bus mice
        (Microsoft, Logitech, PS/2).

        0.4 An Incomplete List of Ported Programs and Other Software

        Most of the common Unix tools and programs have been ported to
        Linux, including almost all of the GNU stuff and many X clients
        from various sources. Actually, ported is often too strong a
        word, since many programs compile out of the box without
        modifications, or only small modifications, because Linux tracks
        POSIX quite closely. Unfortunately, there are not very many
        end-user applications at this time. Nevertheless, here is an
        incomplete list of software that is known to work under Linux.

        Basic Unix commands: ls, tr, sed, awk and so on (you name it,
        we've probably got it).

        Development tools: gcc, gdb, make, bison, flex, perl, rcs, cvs,

        Graphical environments: X11R5 (Xfree86), MGR.

        Editors: GNU Emacs, Lucid Emacs, MicroEmacs, jove, epoch, elvis,
        joe, pico, jed.

        Shells: Bash (Posix sh-compatible), zsh (include ksh
        compatiblity mode), tcsh, csh, rc, ash (mostly sh-compatible),
        and many more.

        Telecommunication: Taylor (BNU-compatible) UUCP, kermit, szrz,
        minicom, pcomm, xcomm, term/slap (runs multiple shells over one
        modem line), and Seyon.

        News and mail: C-news, trn, nn, tin, smail, elm, mh.

        Textprocessing: TeX, groff, doc.

        Games: Nethack, several Muds and X games.

        All of these programs (and this isn't even a hundredth of what
        is available) are freely available.

        0.5 Getting Linux

        0.5.4 Anonymous FTP

        At least the following anonymous ftp sites carry Linux. This
        list is taken from the Meta-FAQ list, which is posted every week
        to the comp.os.linux newsgroup (the Meta-FAQ is updated more
        often than this information sheet, so the list below may not be
        the most current one).

         Textual name                   Numeric address  Linux directory
         =============================  ===============  ===============              /pub/linux            /pub/Linux             /pub/OS/Linux            /pub/linux    /pub/linux    /pub/Linux    /pub/linux  /pub/Linux                /pub/linux              /pub/OS/Linux                  /systems/unix/linux      mirrors/linux          /pub/linux      /pub/linux                                /Linux      /pub/os/linux                                /pub/Linux              /pub/OS/linux and are the official
        sites for Linux' GCC. Some sites mirror other sites. Please use
        the site closest (network-wise) to you whenever possible.

        0.5.5 Other methods of obtaining Linux

        There are many BBS's that have Linux files. A list of them is
        maintained by Zane Healy; he posts it to the comp.os.linux
        newsgroup around the beginning and middle of the month, please
        see that post for more information. comp.os.linux is echoed on
        the LINUX echoid on fidonet. This list is available as, and is mirrored on fine
        mirrors everywhere.

        There is also at least one organization that distributes Linux
        on floppies, for a fee. Contact

               Softlanding Software
               910 Lodge Ave.
               Victoria, B.C., Canada
               +1 604 360 0188
               FAX: 604 385 1292

        for information on purchasing. There is also an organization
        which sells Linux on CD-ROM --- contact

               Yggdrasil Computing, Incorporated
               CDROM sales
               PO Box 8418
               Berkeley, California 94707--8418

        for information on purchasing the CD-ROM. Also, don't forget
        about friends and user's groups, who are usually glad to let you
        make a copy.

        0.5.6 Getting started

        As mentioned at the beginning, Linux is not centrally
        administered. Because of this, there is no ``official'' release
        that one could point at, and say ``That's Linux.'' Instead,
        there are various ``distributions,'' which are more or less
        complete collections of software configured and packaged so that
        they can be used to install a Linux system. The most important
        one is currently the SLS release.

        SLS is put together by Peter MacDonald, and is the more
        full-featured one. It contains much of the available software,
        and includes X. I really recommend SLS to anyone who's serious
        about getting started with Linux.

        The first thing you should do is to get and read the list of
        Frequently Asked Questions (FAQ) from one of the FTP sites, or
        by using the normal Usenet FAQ archives (e.g.
        This document has plenty of instructions on what to do to get
        started, what files you need, and how to solve most of the
        common problems (during installation or otherwise).

        0.6 Legal Status of Linux

        Although Linux is supplied with the complete source code, it is
        copyrighted software, not public domain. However, it is
        available for free under the GNU Public License. See the GPL for
        more information. The programs that run under Linux have each
        their own copyright, although much of it uses the GPL as well.
        All of the software on the FTP site is freely distributable (or
        else it shouldn't be there).

        0.7 News About Linux

        There is a Usenet newsgroup, comp.os.linux, for Linux
        discussion, and also several mailing lists. See the Linux FAQ
        for more information about the mailing lists (you should be able
        to find the FAQ either in the newsgroup or on the FTP sites).

        The newsgroup comp.os.linux.announce is a moderated newsgroup
        for announcements about Linux (new programs, bug fixes, etc).

        For the current status of the Linux kernel and a summary of the
        most recent versions, finger

        There is also a more or less weekly ``newsletter,'' Linux News,
        which summarizes the most important announcements and uploads,
        and has occasional other articles as well. Look in
        comp.os.linux.announce for a sample issue.

        0.8 Future Plans

        Work is underway on Linux version 1.0, which will close some of
        the gaps in the present implementation. The major functionality
        shortcomings are advanced interprocess communication
        (semaphores, shared memory), closer compatibility with POSIX,
        and a lot of tweaking. Documentation is also sorely missing, but
        is being worked on by those on the ``Linux Documentation
        Project'' (the DOC channel of the
        mailing list). Eventually, there will be a complete installation
        and getting started manual for Linux.

        0.9 This document

        This document is maintained by Michael K. Johnson, Please mail me with any comments, no matter
        how small. I can't do a good job of maintaining this document
        without your help. A current copy of this document can always be
        found as, and a .dvi
        version can be found as INFO-SHEET.dvi, in the same directory.

        0.10 Legalese

        Trademarks are owned by their owners. There is no warranty about
        the information in this document. Use and distribute at your own
        risk. The content of this document is in the public domain, but
        please be polite and attribute any quotes.