forked from Minki/linux
b2105aa2c6
Fixed twelve typos in cppc_sysfs.rst, binderfs.rst, paride.rst, zram.rst, bug-hunting.rst, introduction.rst, usage.rst, dm-crypt.rst Signed-off-by: Andrew Klychkov <andrew.a.klychkov@gmail.com> Reviewed-by: Jonathan Corbet <corbet@lwn.net> Reviewed-by: Randy Dunlap <rdunlap@infradead.org> Link: https://lore.kernel.org/r/20201204070235.GA48631@spblnx124.lan Signed-off-by: Jonathan Corbet <corbet@lwn.net>
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===================================
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Linux and parallel port IDE devices
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===================================
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PARIDE v1.03 (c) 1997-8 Grant Guenther <grant@torque.net>
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1. Introduction
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===============
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Owing to the simplicity and near universality of the parallel port interface
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to personal computers, many external devices such as portable hard-disk,
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CD-ROM, LS-120 and tape drives use the parallel port to connect to their
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host computer. While some devices (notably scanners) use ad-hoc methods
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to pass commands and data through the parallel port interface, most
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external devices are actually identical to an internal model, but with
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a parallel-port adapter chip added in. Some of the original parallel port
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adapters were little more than mechanisms for multiplexing a SCSI bus.
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(The Iomega PPA-3 adapter used in the ZIP drives is an example of this
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approach). Most current designs, however, take a different approach.
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The adapter chip reproduces a small ISA or IDE bus in the external device
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and the communication protocol provides operations for reading and writing
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device registers, as well as data block transfer functions. Sometimes,
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the device being addressed via the parallel cable is a standard SCSI
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controller like an NCR 5380. The "ditto" family of external tape
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drives use the ISA replicator to interface a floppy disk controller,
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which is then connected to a floppy-tape mechanism. The vast majority
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of external parallel port devices, however, are now based on standard
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IDE type devices, which require no intermediate controller. If one
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were to open up a parallel port CD-ROM drive, for instance, one would
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find a standard ATAPI CD-ROM drive, a power supply, and a single adapter
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that interconnected a standard PC parallel port cable and a standard
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IDE cable. It is usually possible to exchange the CD-ROM device with
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any other device using the IDE interface.
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The document describes the support in Linux for parallel port IDE
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devices. It does not cover parallel port SCSI devices, "ditto" tape
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drives or scanners. Many different devices are supported by the
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parallel port IDE subsystem, including:
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- MicroSolutions backpack CD-ROM
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- MicroSolutions backpack PD/CD
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- MicroSolutions backpack hard-drives
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- MicroSolutions backpack 8000t tape drive
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- SyQuest EZ-135, EZ-230 & SparQ drives
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- Avatar Shark
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- Imation Superdisk LS-120
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- Maxell Superdisk LS-120
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- FreeCom Power CD
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- Hewlett-Packard 5GB and 8GB tape drives
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- Hewlett-Packard 7100 and 7200 CD-RW drives
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as well as most of the clone and no-name products on the market.
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To support such a wide range of devices, PARIDE, the parallel port IDE
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subsystem, is actually structured in three parts. There is a base
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paride module which provides a registry and some common methods for
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accessing the parallel ports. The second component is a set of
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high-level drivers for each of the different types of supported devices:
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=== =============
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pd IDE disk
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pcd ATAPI CD-ROM
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pf ATAPI disk
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pt ATAPI tape
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pg ATAPI generic
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=== =============
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(Currently, the pg driver is only used with CD-R drives).
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The high-level drivers function according to the relevant standards.
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The third component of PARIDE is a set of low-level protocol drivers
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for each of the parallel port IDE adapter chips. Thanks to the interest
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and encouragement of Linux users from many parts of the world,
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support is available for almost all known adapter protocols:
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==== ====================================== ====
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aten ATEN EH-100 (HK)
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bpck Microsolutions backpack (US)
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comm DataStor (old-type) "commuter" adapter (TW)
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dstr DataStor EP-2000 (TW)
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epat Shuttle EPAT (UK)
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epia Shuttle EPIA (UK)
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fit2 FIT TD-2000 (US)
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fit3 FIT TD-3000 (US)
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friq Freecom IQ cable (DE)
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frpw Freecom Power (DE)
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kbic KingByte KBIC-951A and KBIC-971A (TW)
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ktti KT Technology PHd adapter (SG)
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on20 OnSpec 90c20 (US)
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on26 OnSpec 90c26 (US)
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==== ====================================== ====
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2. Using the PARIDE subsystem
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=============================
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While configuring the Linux kernel, you may choose either to build
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the PARIDE drivers into your kernel, or to build them as modules.
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In either case, you will need to select "Parallel port IDE device support"
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as well as at least one of the high-level drivers and at least one
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of the parallel port communication protocols. If you do not know
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what kind of parallel port adapter is used in your drive, you could
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begin by checking the file names and any text files on your DOS
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installation floppy. Alternatively, you can look at the markings on
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the adapter chip itself. That's usually sufficient to identify the
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correct device.
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You can actually select all the protocol modules, and allow the PARIDE
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subsystem to try them all for you.
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For the "brand-name" products listed above, here are the protocol
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and high-level drivers that you would use:
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================ ============ ====== ========
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Manufacturer Model Driver Protocol
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================ ============ ====== ========
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MicroSolutions CD-ROM pcd bpck
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MicroSolutions PD drive pf bpck
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MicroSolutions hard-drive pd bpck
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MicroSolutions 8000t tape pt bpck
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SyQuest EZ, SparQ pd epat
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Imation Superdisk pf epat
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Maxell Superdisk pf friq
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Avatar Shark pd epat
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FreeCom CD-ROM pcd frpw
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Hewlett-Packard 5GB Tape pt epat
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Hewlett-Packard 7200e (CD) pcd epat
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Hewlett-Packard 7200e (CD-R) pg epat
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================ ============ ====== ========
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2.1 Configuring built-in drivers
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---------------------------------
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We recommend that you get to know how the drivers work and how to
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configure them as loadable modules, before attempting to compile a
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kernel with the drivers built-in.
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If you built all of your PARIDE support directly into your kernel,
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and you have just a single parallel port IDE device, your kernel should
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locate it automatically for you. If you have more than one device,
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you may need to give some command line options to your bootloader
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(eg: LILO), how to do that is beyond the scope of this document.
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The high-level drivers accept a number of command line parameters, all
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of which are documented in the source files in linux/drivers/block/paride.
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By default, each driver will automatically try all parallel ports it
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can find, and all protocol types that have been installed, until it finds
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a parallel port IDE adapter. Once it finds one, the probe stops. So,
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if you have more than one device, you will need to tell the drivers
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how to identify them. This requires specifying the port address, the
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protocol identification number and, for some devices, the drive's
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chain ID. While your system is booting, a number of messages are
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displayed on the console. Like all such messages, they can be
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reviewed with the 'dmesg' command. Among those messages will be
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some lines like::
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paride: bpck registered as protocol 0
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paride: epat registered as protocol 1
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The numbers will always be the same until you build a new kernel with
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different protocol selections. You should note these numbers as you
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will need them to identify the devices.
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If you happen to be using a MicroSolutions backpack device, you will
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also need to know the unit ID number for each drive. This is usually
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the last two digits of the drive's serial number (but read MicroSolutions'
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documentation about this).
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As an example, let's assume that you have a MicroSolutions PD/CD drive
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with unit ID number 36 connected to the parallel port at 0x378, a SyQuest
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EZ-135 connected to the chained port on the PD/CD drive and also an
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Imation Superdisk connected to port 0x278. You could give the following
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options on your boot command::
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pd.drive0=0x378,1 pf.drive0=0x278,1 pf.drive1=0x378,0,36
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In the last option, pf.drive1 configures device /dev/pf1, the 0x378
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is the parallel port base address, the 0 is the protocol registration
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number and 36 is the chain ID.
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Please note: while PARIDE will work both with and without the
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PARPORT parallel port sharing system that is included by the
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"Parallel port support" option, PARPORT must be included and enabled
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if you want to use chains of devices on the same parallel port.
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2.2 Loading and configuring PARIDE as modules
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----------------------------------------------
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It is much faster and simpler to get to understand the PARIDE drivers
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if you use them as loadable kernel modules.
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Note 1:
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using these drivers with the "kerneld" automatic module loading
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system is not recommended for beginners, and is not documented here.
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Note 2:
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if you build PARPORT support as a loadable module, PARIDE must
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also be built as loadable modules, and PARPORT must be loaded before
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the PARIDE modules.
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To use PARIDE, you must begin by::
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insmod paride
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this loads a base module which provides a registry for the protocols,
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among other tasks.
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Then, load as many of the protocol modules as you think you might need.
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As you load each module, it will register the protocols that it supports,
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and print a log message to your kernel log file and your console. For
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example::
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# insmod epat
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paride: epat registered as protocol 0
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# insmod kbic
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paride: k951 registered as protocol 1
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paride: k971 registered as protocol 2
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Finally, you can load high-level drivers for each kind of device that
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you have connected. By default, each driver will autoprobe for a single
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device, but you can support up to four similar devices by giving their
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individual coordinates when you load the driver.
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For example, if you had two no-name CD-ROM drives both using the
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KingByte KBIC-951A adapter, one on port 0x378 and the other on 0x3bc
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you could give the following command::
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# insmod pcd drive0=0x378,1 drive1=0x3bc,1
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For most adapters, giving a port address and protocol number is sufficient,
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but check the source files in linux/drivers/block/paride for more
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information. (Hopefully someone will write some man pages one day !).
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As another example, here's what happens when PARPORT is installed, and
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a SyQuest EZ-135 is attached to port 0x378::
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# insmod paride
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paride: version 1.0 installed
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# insmod epat
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paride: epat registered as protocol 0
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# insmod pd
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pd: pd version 1.0, major 45, cluster 64, nice 0
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pda: Sharing parport1 at 0x378
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pda: epat 1.0, Shuttle EPAT chip c3 at 0x378, mode 5 (EPP-32), delay 1
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pda: SyQuest EZ135A, 262144 blocks [128M], (512/16/32), removable media
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pda: pda1
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Note that the last line is the output from the generic partition table
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scanner - in this case it reports that it has found a disk with one partition.
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2.3 Using a PARIDE device
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--------------------------
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Once the drivers have been loaded, you can access PARIDE devices in the
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same way as their traditional counterparts. You will probably need to
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create the device "special files". Here is a simple script that you can
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cut to a file and execute::
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#!/bin/bash
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#
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# mkd -- a script to create the device special files for the PARIDE subsystem
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#
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function mkdev {
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mknod $1 $2 $3 $4 ; chmod 0660 $1 ; chown root:disk $1
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}
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#
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function pd {
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D=$( printf \\$( printf "x%03x" $[ $1 + 97 ] ) )
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mkdev pd$D b 45 $[ $1 * 16 ]
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for P in 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
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do mkdev pd$D$P b 45 $[ $1 * 16 + $P ]
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done
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}
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#
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cd /dev
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#
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for u in 0 1 2 3 ; do pd $u ; done
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for u in 0 1 2 3 ; do mkdev pcd$u b 46 $u ; done
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for u in 0 1 2 3 ; do mkdev pf$u b 47 $u ; done
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for u in 0 1 2 3 ; do mkdev pt$u c 96 $u ; done
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for u in 0 1 2 3 ; do mkdev npt$u c 96 $[ $u + 128 ] ; done
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for u in 0 1 2 3 ; do mkdev pg$u c 97 $u ; done
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#
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# end of mkd
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With the device files and drivers in place, you can access PARIDE devices
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like any other Linux device. For example, to mount a CD-ROM in pcd0, use::
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mount /dev/pcd0 /cdrom
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If you have a fresh Avatar Shark cartridge, and the drive is pda, you
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might do something like::
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fdisk /dev/pda -- make a new partition table with
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partition 1 of type 83
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mke2fs /dev/pda1 -- to build the file system
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mkdir /shark -- make a place to mount the disk
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mount /dev/pda1 /shark
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Devices like the Imation superdisk work in the same way, except that
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they do not have a partition table. For example to make a 120MB
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floppy that you could share with a DOS system::
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mkdosfs /dev/pf0
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mount /dev/pf0 /mnt
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2.4 The pf driver
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------------------
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The pf driver is intended for use with parallel port ATAPI disk
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devices. The most common devices in this category are PD drives
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and LS-120 drives. Traditionally, media for these devices are not
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partitioned. Consequently, the pf driver does not support partitioned
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media. This may be changed in a future version of the driver.
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2.5 Using the pt driver
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------------------------
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The pt driver for parallel port ATAPI tape drives is a minimal driver.
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It does not yet support many of the standard tape ioctl operations.
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For best performance, a block size of 32KB should be used. You will
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probably want to set the parallel port delay to 0, if you can.
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2.6 Using the pg driver
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------------------------
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The pg driver can be used in conjunction with the cdrecord program
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to create CD-ROMs. Please get cdrecord version 1.6.1 or later
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from ftp://ftp.fokus.gmd.de/pub/unix/cdrecord/ . To record CD-R media
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your parallel port should ideally be set to EPP mode, and the "port delay"
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should be set to 0. With those settings it is possible to record at 2x
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speed without any buffer underruns. If you cannot get the driver to work
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in EPP mode, try to use "bidirectional" or "PS/2" mode and 1x speeds only.
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3. Troubleshooting
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==================
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3.1 Use EPP mode if you can
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----------------------------
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The most common problems that people report with the PARIDE drivers
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concern the parallel port CMOS settings. At this time, none of the
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PARIDE protocol modules support ECP mode, or any ECP combination modes.
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If you are able to do so, please set your parallel port into EPP mode
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using your CMOS setup procedure.
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3.2 Check the port delay
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-------------------------
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Some parallel ports cannot reliably transfer data at full speed. To
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offset the errors, the PARIDE protocol modules introduce a "port
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delay" between each access to the i/o ports. Each protocol sets
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a default value for this delay. In most cases, the user can override
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the default and set it to 0 - resulting in somewhat higher transfer
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rates. In some rare cases (especially with older 486 systems) the
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default delays are not long enough. if you experience corrupt data
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transfers, or unexpected failures, you may wish to increase the
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port delay. The delay can be programmed using the "driveN" parameters
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to each of the high-level drivers. Please see the notes above, or
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read the comments at the beginning of the driver source files in
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linux/drivers/block/paride.
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3.3 Some drives need a printer reset
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-------------------------------------
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There appear to be a number of "noname" external drives on the market
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that do not always power up correctly. We have noticed this with some
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drives based on OnSpec and older Freecom adapters. In these rare cases,
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the adapter can often be reinitialised by issuing a "printer reset" on
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the parallel port. As the reset operation is potentially disruptive in
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multiple device environments, the PARIDE drivers will not do it
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automatically. You can however, force a printer reset by doing::
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insmod lp reset=1
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rmmod lp
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If you have one of these marginal cases, you should probably build
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your paride drivers as modules, and arrange to do the printer reset
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before loading the PARIDE drivers.
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3.4 Use the verbose option and dmesg if you need help
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------------------------------------------------------
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While a lot of testing has gone into these drivers to make them work
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as smoothly as possible, problems will arise. If you do have problems,
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please check all the obvious things first: does the drive work in
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DOS with the manufacturer's drivers ? If that doesn't yield any useful
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clues, then please make sure that only one drive is hooked to your system,
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and that either (a) PARPORT is enabled or (b) no other device driver
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is using your parallel port (check in /proc/ioports). Then, load the
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appropriate drivers (you can load several protocol modules if you want)
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as in::
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# insmod paride
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# insmod epat
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# insmod bpck
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# insmod kbic
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...
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# insmod pd verbose=1
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(using the correct driver for the type of device you have, of course).
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The verbose=1 parameter will cause the drivers to log a trace of their
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activity as they attempt to locate your drive.
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Use 'dmesg' to capture a log of all the PARIDE messages (any messages
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beginning with paride:, a protocol module's name or a driver's name) and
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include that with your bug report. You can submit a bug report in one
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of two ways. Either send it directly to the author of the PARIDE suite,
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by e-mail to grant@torque.net, or join the linux-parport mailing list
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and post your report there.
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3.5 For more information or help
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---------------------------------
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You can join the linux-parport mailing list by sending a mail message
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to:
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linux-parport-request@torque.net
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with the single word::
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subscribe
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in the body of the mail message (not in the subject line). Please be
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sure that your mail program is correctly set up when you do this, as
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the list manager is a robot that will subscribe you using the reply
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address in your mail headers. REMOVE any anti-spam gimmicks you may
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have in your mail headers, when sending mail to the list server.
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You might also find some useful information on the linux-parport
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web pages (although they are not always up to date) at
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http://web.archive.org/web/%2E/http://www.torque.net/parport/
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