===================================Linux and parallel port IDE devices=================================== PARIDE v1.03   (c) 1997-8  Grant Guenther <grant@torque.net>PATA_PARPORT   (c) 2023 Ondrej Zary 1. Introduction=============== Owing to the simplicity and near universality of the parallel port interfaceto personal computers, many external devices such as portable hard-disk,CD-ROM, LS-120 and tape drives use the parallel port to connect to theirhost computer.  While some devices (notably scanners) use ad-hoc methodsto pass commands and data through the parallel port interface, mostexternal devices are actually identical to an internal model, but witha parallel-port adapter chip added in.  Some of the original parallel portadapters were little more than mechanisms for multiplexing a SCSI bus.(The Iomega PPA-3 adapter used in the ZIP drives is an example of thisapproach).  Most current designs, however, take a different approach.The adapter chip reproduces a small ISA or IDE bus in the external deviceand the communication protocol provides operations for reading and writingdevice registers, as well as data block transfer functions.  Sometimes,the device being addressed via the parallel cable is a standard SCSIcontroller like an NCR 5380.  The "ditto" family of external tapedrives use the ISA replicator to interface a floppy disk controller,which is then connected to a floppy-tape mechanism.  The vast majorityof external parallel port devices, however, are now based on standardIDE type devices, which require no intermediate controller.  If onewere to open up a parallel port CD-ROM drive, for instance, one wouldfind a standard ATAPI CD-ROM drive, a power supply, and a single adapterthat interconnected a standard PC parallel port cable and a standardIDE cable.  It is usually possible to exchange the CD-ROM device withany other device using the IDE interface. The document describes the support in Linux for parallel port IDEdevices.  It does not cover parallel port SCSI devices, "ditto" tapedrives or scanners.  Many different devices are supported by theparallel port IDE subsystem, including: 	- MicroSolutions backpack CD-ROM	- MicroSolutions backpack PD/CD	- MicroSolutions backpack hard-drives	- MicroSolutions backpack 8000t tape drive	- SyQuest EZ-135, EZ-230 & SparQ drives	- Avatar Shark	- Imation Superdisk LS-120	- Maxell Superdisk LS-120	- FreeCom Power CD	- Hewlett-Packard 5GB and 8GB tape drives	- Hewlett-Packard 7100 and 7200 CD-RW drives as well as most of the clone and no-name products on the market. To support such a wide range of devices, pata_parport is actually structuredin two parts. There is a base pata_parport module which provides an interfaceto kernel libata subsystem, registry and some common methods for accessingthe parallel ports. The second component is a set of low-level protocol drivers for each of theparallel port IDE adapter chips.  Thanks to the interest and encouragement ofLinux users from many parts of the world, support is available for almost allknown adapter protocols: 	====    ====================================== ====        aten    ATEN EH-100                            (HK)        bpck    Microsolutions backpack                (US)        comm    DataStor (old-type) "commuter" adapter (TW)        dstr    DataStor EP-2000                       (TW)        epat    Shuttle EPAT                           (UK)        epia    Shuttle EPIA                           (UK)	fit2    FIT TD-2000			       (US)	fit3    FIT TD-3000			       (US)	friq    Freecom IQ cable                       (DE)        frpw    Freecom Power                          (DE)        kbic    KingByte KBIC-951A and KBIC-971A       (TW)	ktti    KT Technology PHd adapter              (SG)        on20    OnSpec 90c20                           (US)        on26    OnSpec 90c26                           (US)	====    ====================================== ====  2. Using pata_parport subsystem=============================== While configuring the Linux kernel, you may choose either to buildthe pata_parport drivers into your kernel, or to build them as modules. In either case, you will need to select "Parallel port IDE device support"and at least one of the parallel port communication protocols.If you do not know what kind of parallel port adapter is used in your drive,you could begin by checking the file names and any text files on your DOSinstallation floppy.  Alternatively, you can look at the markings onthe adapter chip itself.  That's usually sufficient to identify thecorrect device. You can actually select all the protocol modules, and allow the pata_parportsubsystem to try them all for you. For the "brand-name" products listed above, here are the protocoland high-level drivers that you would use: 	================	============	========	Manufacturer		Model		Protocol	================	============	========	MicroSolutions		CD-ROM		bpck	MicroSolutions		PD drive	bpck	MicroSolutions		hard-drive	bpck	MicroSolutions          8000t tape      bpck	SyQuest			EZ, SparQ	epat	Imation			Superdisk	epat	Maxell                  Superdisk       friq	Avatar			Shark		epat	FreeCom			CD-ROM		frpw	Hewlett-Packard		5GB Tape	epat	Hewlett-Packard		7200e (CD)	epat	Hewlett-Packard		7200e (CD-R)	epat	================	============	======== All parports and all protocol drivers are probed automatically unless probe=0parameter is used. So just "modprobe epat" is enough for an Imation SuperDiskdrive to work. Manual device creation:: 	# echo "port protocol mode unit delay" >/sys/bus/pata_parport/new_device where: 	======== ================================================	port	 parport name (or "auto" for all parports)	protocol protocol name (or "auto" for all protocols)	mode	 mode number (protocol-specific) or -1 for probe	unit	 unit number (for backpack only, see below)	delay	 I/O delay (see troubleshooting section below)	======== ================================================ If you happen to be using a MicroSolutions backpack device, you willalso need to know the unit ID number for each drive.  This is usuallythe last two digits of the drive's serial number (but read MicroSolutions'documentation about this). If you omit the parameters from the end, defaults will be used, e.g.: Probe all parports with all protocols:: 	# echo auto >/sys/bus/pata_parport/new_device Probe parport0 using protocol epat and mode 4 (EPP-16):: 	# echo "parport0 epat 4" >/sys/bus/pata_parport/new_device Probe parport0 using all protocols:: 	# echo "parport0 auto" >/sys/bus/pata_parport/new_device Probe all parports using protoocol epat:: 	# echo "auto epat" >/sys/bus/pata_parport/new_device Deleting devices:: 	# echo pata_parport.0 >/sys/bus/pata_parport/delete_device  3. Troubleshooting================== 3.1  Use EPP mode if you can---------------------------- The most common problems that people report with the pata_parport driversconcern the parallel port CMOS settings.  At this time, none of theprotocol modules support ECP mode, or any ECP combination modes.If you are able to do so, please set your parallel port into EPP modeusing your CMOS setup procedure. 3.2  Check the port delay------------------------- Some parallel ports cannot reliably transfer data at full speed.  Tooffset the errors, the protocol modules introduce a "portdelay" between each access to the i/o ports.  Each protocol setsa default value for this delay.  In most cases, the user can overridethe default and set it to 0 - resulting in somewhat higher transferrates.  In some rare cases (especially with older 486 systems) thedefault delays are not long enough.  if you experience corrupt datatransfers, or unexpected failures, you may wish to increase theport delay. 3.3  Some drives need a printer reset------------------------------------- There appear to be a number of "noname" external drives on the marketthat do not always power up correctly.  We have noticed this with somedrives based on OnSpec and older Freecom adapters.  In these rare cases,the adapter can often be reinitialised by issuing a "printer reset" onthe parallel port.  As the reset operation is potentially disruptive inmultiple device environments, the pata_parport drivers will not do itautomatically.  You can however, force a printer reset by doing:: 	insmod lp reset=1	rmmod lp If you have one of these marginal cases, you should probably buildyour pata_parport drivers as modules, and arrange to do the printer resetbefore loading the pata_parport drivers.