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<sect1 id="supported-peripherals">
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<title>Peripherals and Other Hardware</title>
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Linux supports a large variety of hardware devices such as mice,
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printers, scanners, PCMCIA and USB devices. However, most of these
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devices are not required while installing the system.
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</para><para arch="i386">
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USB hardware generally works fine, only some
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USB keyboards may require additional configuration
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(see <xref linkend="usb-keyboard-config"/>).
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</para><para arch="i386">
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<ulink url="&url-hardware-howto;">Linux Hardware Compatibility HOWTO</ulink>
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to determine whether your specific hardware is supported by Linux.
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</para><para arch="s390">
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Package installations from XPRAM and tape are not supported by this
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system. All packages that you want to install need to be available on a
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DASD or over the network using NFS, HTTP or FTP.
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</para><para arch="mips">
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The Broadcom BCM1250 evaluation board offers standard 3.3v 32 bit and 64
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bit PCI slots as well as USB connectors.
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</para><para arch="mipsel">
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The Broadcom BCM1250 evaluation board offers standard 3.3v 32 bit and 64
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bit PCI slots as well as USB connectors. The Cobalt RaQ has no support for
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additional devices but the Qube has one PCI slot.
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<sect1 arch="not-s390"><title>Purchasing Hardware Specifically for GNU/Linux</title>
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There are several vendors, who ship systems with Debian or other
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distributions of GNU/Linux
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<ulink url="&url-pre-installed;">pre-installed</ulink>. You might pay more
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for the privilege, but it does buy a level of peace of mind, since you can
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be sure that the hardware is well-supported by GNU/Linux.
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</para><para arch="m68k">
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Unfortunately, it's quite rare to find any vendor shipping
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new &arch-title; machines at all.
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</para><para arch="i386">
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If you do have to buy a machine with Windows bundled, carefully read
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the software license that comes with Windows; you may be able to
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reject the license and obtain a rebate from your vendor. See
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<ulink url="&url-windows-refund;"></ulink> for complete details.
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Whether or not you are purchasing a system with Linux bundled, or even
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a used system, it is still important to check that your hardware is
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supported by the Linux kernel. Check if your hardware is listed in
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the references found above. Let your salesperson (if any) know that
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you're shopping for a Linux system. Support Linux-friendly hardware
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<sect2><title>Avoid Proprietary or Closed Hardware</title>
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Some hardware manufacturers simply won't tell us how to write drivers
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for their hardware. Others won't allow us access to the documentation
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without a non-disclosure agreement that would prevent us from
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releasing the Linux source code.
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</para><para arch="m68k">
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Another example is the proprietary hardware in the older
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Macintosh line. In fact, no specifications or documentation have ever
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been released for any Macintosh hardware, most notably the ADB
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controller (used by the mouse and keyboard), the floppy controller,
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and all acceleration and CLUT manipulation of the video hardware
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(though we do now support CLUT manipulation on nearly all internal
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video chips). In a nutshell, this explains why the Macintosh Linux
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port lags behind other Linux ports.
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Since we haven't been granted access to the documentation on these
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devices, they simply won't work under Linux. You can help by asking
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the manufacturers of such hardware to release the documentation. If
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enough people ask, they will realize that the free software community
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is an important market.
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<sect2 arch="i386"><title>Windows-specific Hardware</title>
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A disturbing trend is the proliferation of Windows-specific modems and
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printers. In some cases these are specially designed to be operated by
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the Microsoft Windows operating system and bear the legend
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``WinModem'' or ``Made especially for Windows-based computers''. This
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is generally done by removing the embedded processors of the hardware
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and shifting the work they do over to a Windows driver that is run by
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your computer's main CPU. This strategy makes the hardware less
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expensive, but the savings are often <emphasis>not</emphasis> passed on to the
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user and this hardware may even be more expensive than equivalent
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devices that retain their embedded intelligence.
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You should avoid Windows-specific hardware for two reasons. The first
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is that the manufacturers do not generally make the resources
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available to write a Linux driver. Generally, the hardware and
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software interface to the device is proprietary, and documentation is
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not available without a non-disclosure agreement, if it is available
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at all. This precludes its being used for free software, since free
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software writers disclose the source code of their programs. The
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second reason is that when devices like these have had their embedded
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processors removed, the operating system must perform the work of the
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embedded processors, often at <emphasis>real-time</emphasis> priority,
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and thus the CPU is not available to run your programs while it is
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driving these devices. Since the typical Windows user does not
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multi-process as intensively as a Linux user, the manufacturers hope
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that the Windows user simply won't notice the burden this hardware
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places on their CPU. However, any multi-processing operating system,
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even Windows 2000 or XP, suffers from degraded performance when
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peripheral manufacturers skimp on the embedded processing power of
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You can help this situation by encouraging these manufacturers to
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release the documentation and other resources necessary for us to
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program their hardware, but the best strategy is simply to avoid this
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sort of hardware until it is listed as working in the
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<ulink url="&url-hardware-howto;">Linux Hardware Compatibility HOWTO</ulink>.
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<sect2 id="Parity-RAM">
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<title>Fake or <quote>Virtual</quote> Parity RAM</title>
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If you ask for Parity RAM in a computer store, you'll probably get
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<emphasis>virtual parity</emphasis> memory modules instead of
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<emphasis>true parity</emphasis> ones. Virtual parity SIMMs can often
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(but not always) be distinguished because they only have one more chip
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than an equivalent non-parity SIMM, and that one extra chip is smaller
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than all the others. Virtual-parity SIMMs work exactly like non-parity
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memory. They can't tell you when you have a single-bit RAM error the
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way true-parity SIMMs do in a motherboard that implements
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parity. Don't ever pay more for a virtual-parity SIMM than a
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non-parity one. Do expect to pay a little more for true-parity SIMMs,
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because you are actually buying one extra bit of memory for every 8
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If you want complete information on &arch-title; RAM issues, and what
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is the best RAM to buy, see the
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<ulink url="&url-pc-hw-faq;">PC Hardware FAQ</ulink>.
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</para><para arch="alpha">
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Most, if not all, Alpha systems require true-parity RAM.