256 lines
8.4 KiB
ReStructuredText
256 lines
8.4 KiB
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=============
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Floppy Driver
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=============
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FAQ list:
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=========
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A FAQ list may be found in the fdutils package (see below), and also
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at <https://fdutils.linux.lu/faq.html>.
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LILO configuration options (Thinkpad users, read this)
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======================================================
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The floppy driver is configured using the 'floppy=' option in
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lilo. This option can be typed at the boot prompt, or entered in the
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lilo configuration file.
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Example: If your kernel is called linux-2.6.9, type the following line
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at the lilo boot prompt (if you have a thinkpad)::
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linux-2.6.9 floppy=thinkpad
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You may also enter the following line in /etc/lilo.conf, in the description
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of linux-2.6.9::
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append = "floppy=thinkpad"
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Several floppy related options may be given, example::
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linux-2.6.9 floppy=daring floppy=two_fdc
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append = "floppy=daring floppy=two_fdc"
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If you give options both in the lilo config file and on the boot
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prompt, the option strings of both places are concatenated, the boot
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prompt options coming last. That's why there are also options to
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restore the default behavior.
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Module configuration options
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============================
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If you use the floppy driver as a module, use the following syntax::
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modprobe floppy floppy="<options>"
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Example::
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modprobe floppy floppy="omnibook messages"
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If you need certain options enabled every time you load the floppy driver,
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you can put::
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options floppy floppy="omnibook messages"
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in a configuration file in /etc/modprobe.d/.
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The floppy driver related options are:
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floppy=asus_pci
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Sets the bit mask to allow only units 0 and 1. (default)
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floppy=daring
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Tells the floppy driver that you have a well behaved floppy controller.
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This allows more efficient and smoother operation, but may fail on
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certain controllers. This may speed up certain operations.
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floppy=0,daring
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Tells the floppy driver that your floppy controller should be used
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with caution.
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floppy=one_fdc
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Tells the floppy driver that you have only one floppy controller.
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(default)
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floppy=two_fdc / floppy=<address>,two_fdc
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Tells the floppy driver that you have two floppy controllers.
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The second floppy controller is assumed to be at <address>.
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This option is not needed if the second controller is at address
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0x370, and if you use the 'cmos' option.
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floppy=thinkpad
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Tells the floppy driver that you have a Thinkpad. Thinkpads use an
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inverted convention for the disk change line.
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floppy=0,thinkpad
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Tells the floppy driver that you don't have a Thinkpad.
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floppy=omnibook / floppy=nodma
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Tells the floppy driver not to use Dma for data transfers.
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This is needed on HP Omnibooks, which don't have a workable
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DMA channel for the floppy driver. This option is also useful
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if you frequently get "Unable to allocate DMA memory" messages.
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Indeed, dma memory needs to be continuous in physical memory,
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and is thus harder to find, whereas non-dma buffers may be
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allocated in virtual memory. However, I advise against this if
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you have an FDC without a FIFO (8272A or 82072). 82072A and
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later are OK. You also need at least a 486 to use nodma.
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If you use nodma mode, I suggest you also set the FIFO
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threshold to 10 or lower, in order to limit the number of data
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transfer interrupts.
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If you have a FIFO-able FDC, the floppy driver automatically
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falls back on non DMA mode if no DMA-able memory can be found.
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If you want to avoid this, explicitly ask for 'yesdma'.
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floppy=yesdma
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Tells the floppy driver that a workable DMA channel is available.
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(default)
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floppy=nofifo
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Disables the FIFO entirely. This is needed if you get "Bus
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master arbitration error" messages from your Ethernet card (or
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from other devices) while accessing the floppy.
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floppy=usefifo
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Enables the FIFO. (default)
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floppy=<threshold>,fifo_depth
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Sets the FIFO threshold. This is mostly relevant in DMA
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mode. If this is higher, the floppy driver tolerates more
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interrupt latency, but it triggers more interrupts (i.e. it
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imposes more load on the rest of the system). If this is
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lower, the interrupt latency should be lower too (faster
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processor). The benefit of a lower threshold is less
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interrupts.
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To tune the fifo threshold, switch on over/underrun messages
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using 'floppycontrol --messages'. Then access a floppy
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disk. If you get a huge amount of "Over/Underrun - retrying"
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messages, then the fifo threshold is too low. Try with a
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higher value, until you only get an occasional Over/Underrun.
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It is a good idea to compile the floppy driver as a module
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when doing this tuning. Indeed, it allows to try different
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fifo values without rebooting the machine for each test. Note
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that you need to do 'floppycontrol --messages' every time you
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re-insert the module.
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Usually, tuning the fifo threshold should not be needed, as
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the default (0xa) is reasonable.
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floppy=<drive>,<type>,cmos
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Sets the CMOS type of <drive> to <type>. This is mandatory if
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you have more than two floppy drives (only two can be
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described in the physical CMOS), or if your BIOS uses
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non-standard CMOS types. The CMOS types are:
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== ==================================
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0 Use the value of the physical CMOS
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1 5 1/4 DD
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2 5 1/4 HD
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3 3 1/2 DD
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4 3 1/2 HD
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5 3 1/2 ED
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6 3 1/2 ED
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16 unknown or not installed
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== ==================================
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(Note: there are two valid types for ED drives. This is because 5 was
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initially chosen to represent floppy *tapes*, and 6 for ED drives.
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AMI ignored this, and used 5 for ED drives. That's why the floppy
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driver handles both.)
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floppy=unexpected_interrupts
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Print a warning message when an unexpected interrupt is received.
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(default)
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floppy=no_unexpected_interrupts / floppy=L40SX
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Don't print a message when an unexpected interrupt is received. This
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is needed on IBM L40SX laptops in certain video modes. (There seems
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to be an interaction between video and floppy. The unexpected
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interrupts affect only performance, and can be safely ignored.)
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floppy=broken_dcl
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Don't use the disk change line, but assume that the disk was
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changed whenever the device node is reopened. Needed on some
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boxes where the disk change line is broken or unsupported.
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This should be regarded as a stopgap measure, indeed it makes
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floppy operation less efficient due to unneeded cache
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flushings, and slightly more unreliable. Please verify your
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cable, connection and jumper settings if you have any DCL
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problems. However, some older drives, and also some laptops
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are known not to have a DCL.
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floppy=debug
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Print debugging messages.
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floppy=messages
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Print informational messages for some operations (disk change
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notifications, warnings about over and underruns, and about
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autodetection).
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floppy=silent_dcl_clear
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Uses a less noisy way to clear the disk change line (which
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doesn't involve seeks). Implied by 'daring' option.
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floppy=<nr>,irq
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Sets the floppy IRQ to <nr> instead of 6.
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floppy=<nr>,dma
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Sets the floppy DMA channel to <nr> instead of 2.
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floppy=slow
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Use PS/2 stepping rate::
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PS/2 floppies have much slower step rates than regular floppies.
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It's been recommended that take about 1/4 of the default speed
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in some more extreme cases.
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Supporting utilities and additional documentation:
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==================================================
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Additional parameters of the floppy driver can be configured at
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runtime. Utilities which do this can be found in the fdutils package.
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This package also contains a new version of mtools which allows to
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access high capacity disks (up to 1992K on a high density 3 1/2 disk!).
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It also contains additional documentation about the floppy driver.
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The latest version can be found at fdutils homepage:
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https://fdutils.linux.lu
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The fdutils releases can be found at:
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https://fdutils.linux.lu/download.html
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http://www.tux.org/pub/knaff/fdutils/
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ftp://metalab.unc.edu/pub/Linux/utils/disk-management/
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Reporting problems about the floppy driver
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==========================================
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If you have a question or a bug report about the floppy driver, mail
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me at Alain.Knaff@poboxes.com . If you post to Usenet, preferably use
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comp.os.linux.hardware. As the volume in these groups is rather high,
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be sure to include the word "floppy" (or "FLOPPY") in the subject
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line. If the reported problem happens when mounting floppy disks, be
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sure to mention also the type of the filesystem in the subject line.
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Be sure to read the FAQ before mailing/posting any bug reports!
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Alain
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Changelog
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=========
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10-30-2004 :
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Cleanup, updating, add reference to module configuration.
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James Nelson <james4765@gmail.com>
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6-3-2000 :
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Original Document
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