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<sect2 arch="x86" id="bios-setup"><title>Invoking the BIOS Set-Up Menu</title>
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BIOS provides the basic functions needed to boot your machine to allow
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your operating system to access your hardware. Your system probably
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provides a BIOS setup menu, which is used to configure the BIOS.
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Before installing, you <emphasis>must</emphasis> ensure that your BIOS
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is set up correctly; not doing so can lead to intermittent crashes or
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an inability to install Debian.
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The rest of this section is lifted from the
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<ulink url="&url-pc-hw-faq;"></ulink>, answering the question, "How do I
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enter the CMOS configuration menu?". How you access the BIOS (or
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``CMOS'') configuration menu depends on who wrote your BIOS software:
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<!-- From: burnesa@cat.com (Shaun Burnet) -->
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<keycap>Delete</keycap> key during the POST (power on self test)
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<term>Award BIOS</term>
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<keycap>Ctrl</keycap><keycap>Alt</keycap><keycap>Esc</keycap>
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</keycombo>, or <keycap>Delete</keycap> key during the POST
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<varlistentry><term>DTK BIOS</term>
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<keycap>Esc</keycap> key during the POST
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<varlistentry><term>IBM PS/2 BIOS</term>
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<keycap>Ctrl</keycap><keycap>Alt</keycap><keycap>Insert</keycap>
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<keycap>Ctrl</keycap><keycap>Alt</keycap><keycap>Delete</keycap>
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<term>Phoenix BIOS</term>
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<keycap>Ctrl</keycap><keycap>Alt</keycap><keycap>Esc</keycap>
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<keycap>Ctrl</keycap><keycap>Alt</keycap><keycap>S</keycap>
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Information on invoking other BIOS routines can be found in
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<ulink url="&url-invoking-bios-info;"></ulink>.
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Some &arch-title; machines don't have a CMOS configuration menu in the
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BIOS. They require a software CMOS setup program. If you don't have
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the Installation and/or Diagnostics diskette for your machine, you can
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try using a shareware/freeware program. Try looking in
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<ulink url="&url-simtel;"></ulink>.
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<sect2 arch="x86" id="boot-dev-select"><title>Boot Device Selection</title>
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Many BIOS setup menus allow you to select the devices that will be
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used to bootstrap the system. Set this to look for a bootable
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operating system on <filename>A:</filename> (the first floppy disk),
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then optionally the first CD-ROM device (possibly appearing as
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<filename>D:</filename> or <filename>E:</filename>), and then from
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<filename>C:</filename> (the first hard disk). This setting enables
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you to boot from either a floppy disk or a CD-ROM, which are the two
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most common boot devices used to install Debian.
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If you have a newer SCSI controller and you have a CD-ROM device
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attached to it, you are usually able to boot from the CD-ROM. All you
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have to do is enable booting from a CD-ROM in the SCSI-BIOS of your
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Other popular option is to boot from a USB storage (also called USB
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memory stick or USB key). Some BIOSes can boot USB storage directly,
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and some cannot. You may need to configure your BIOS to boot from
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a <quote>Removable drive</quote> or even a <quote>USB-ZIP</quote> to
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get it to boot from the USB device.
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Here are some details about how to set the boot order. Remember to
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reset the boot order after Linux is installed, so that you restart
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your machine from the hard drive.
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<title>Changing the Boot Order on IDE Computers</title>
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As your computer starts, press the keys to enter the BIOS
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utility. Often, it is the <keycap>Delete</keycap> key. However,
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consult the hardware documentation for the exact keystrokes.
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Find the boot sequence in the setup utility. Its location depends on
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your BIOS, but you are looking for a field that lists drives.
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Common entries on IDE machines are C, A, cdrom or A, C, cdrom.
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C is the hard drive, and A is the floppy drive.
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Change the boot sequence setting so that the CD-ROM or the
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floppy is first. Usually, the <keycap>Page Up</keycap> or
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<keycap>Page Down</keycap> keys cycle
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through the possible choices.
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Save your changes. Instructions on the screen tell you how to
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save the changes on your computer.
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<title>Changing the Boot Order on SCSI Computers</title>
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As your computer starts, press the keys to enter the SCSI setup
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You can start the SCSI setup utility after the memory check and
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the message about how to start the BIOS utility displays when you
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The keystrokes you need depend on the utility. Often, it is
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<keycombo><keycap>Ctrl</keycap><keycap>F2</keycap></keycombo>.
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However, consult your hardware documentation for the
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Find the utility for changing the boot order.
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Set the utility so that the SCSI ID of the CD drive is first on
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Save your changes. Instructions on the screen tell you how to
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save the changes on your computer. Often, you must press
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<keycap>F10</keycap>.
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<title>Miscellaneous BIOS Settings</title>
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<sect3 id="cd-settings"><title>CD-ROM Settings</title>
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Some BIOS systems (such as Award BIOS) allow you to automatically set
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the CD speed. You should avoid that, and instead set it to, say, the
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lowest speed. If you get <userinput>seek failed</userinput> error
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messages, this may be your problem.
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<sect3><title>Extended vs. Expanded Memory</title>
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If your system provides both ex<emphasis>ten</emphasis>ded and
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ex<emphasis>pan</emphasis>ded memory, set it so that there is as much
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extended and as little expanded memory as possible. Linux requires
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extended memory and cannot use expanded memory.
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<sect3><title>Virus Protection</title>
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Disable any virus-warning features your BIOS may provide. If you have
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a virus-protection board or other special hardware, make sure it is
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disabled or physically removed while running GNU/Linux. These aren't
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compatible with GNU/Linux; moreover, due to the file system
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permissions and protected memory of the Linux kernel, viruses are
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After installation you can enable Boot Sector protection if you
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want. This offers no additional security in Linux but if you also run
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Windows it may prevent a catastrophe. There is no need to tamper with
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the Master Boot Record (MBR) after the boot manager has been set up.
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<sect3><title>Shadow RAM</title>
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Your motherboard may provide <emphasis>shadow RAM</emphasis> or BIOS
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caching. You may see settings for ``Video BIOS Shadow'', ``C800-CBFF
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Shadow'', etc. <emphasis>Disable</emphasis> all shadow RAM. Shadow
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RAM is used to accelerate access to the ROMs on your motherboard and
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on some of the controller cards. Linux does not use these ROMs once it
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has booted because it provides its own faster 32-bit software in place
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of the 16-bit programs in the ROMs. Disabling the shadow RAM may make
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some of it available for programs to use as normal memory. Leaving
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the shadow RAM enabled may interfere with Linux access to hardware
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<sect3><title>Memory Hole</title>
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If your BIOS offers something like ``15-16 MB Memory Hole'', please
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disable that. Linux expects to find memory there if you have that much
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We have a report of an Intel Endeavor motherboard on which there is an
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option called ``LFB'' or ``Linear Frame Buffer''. This had two
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settings: ``Disabled'' and ``1 Megabyte''. Set it to ``1 Megabyte''.
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When disabled, the installation floppy was not read correctly, and the
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system eventually crashed. At this writing we don't understand what's
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going on with this particular device — it just worked with that
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setting and not without it.
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<!-- no other platforms other than x86 provide this sort of thing, AFAIK -->
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<sect3><title>Advanced Power Management</title>
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If your motherboard provides Advanced Power Management (APM),
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configure it so that power management is controlled by APM. Disable
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the doze, standby, suspend, nap, and sleep modes, and disable the hard
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disk's power-down timer. Linux can take over control of these modes,
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and can do a better job of power-management than the BIOS.