comp.sys.ibm.pc.hardware.storage,comp.sys.ibm.pc.hardware.misc,comp.answers,news.answersSubject: Enhanced IDE/Fast-ATA/ATA-2 FAQ [1 of 2]Followup-To: posterDate: 24 Jan 2000 10:58:49 GMTOrganization: University of Nijmegen, The NetherlandsLines: 2094Approved: news-answers-request@MIT.EDUMessage-ID: <86hb99$70e$1@wnnews.sci.kun.nl>NNTP-Posting-Host: wn4.sci.kun.nlX-Trace: wnnews.sci.kun.nl 948711529 7182 131.174.8.3 (24 Jan 2000 10:58:49 GMT)X-Complaints-To: usenet@sci.kun.nlNNTP-Posting-Date: 24 Jan 2000 10:58:49 GMTSummary: This FAQ addresses issues surrounding Enhanced IDE, ATA-2,    ATAPI and Enhanced BIOSes. It includes practical questions,    background information and lists of net resources.Precedence: bulkXref: senator-bedfellow.mit.edu comp.sys.ibm.pc.hardware.storage:202953 comp.sys.ibm.pc.hardware.misc:148803 comp.answers:39389 news.answers:175809http://come.to/eide>     The HTML version should also be online on  o  <http://www.wi.leidenuniv.nl/ata/>     and the text version is available by FTP from  o  <ftp://ftp.netcom.com/pub/cl/clau/ide_ata/>  o  <ftp://ftp.rahul.net/pub/lps/hard-disk/>  o  <ftp://ftp.wi.leidenuniv.nl/pub/faqs/>  o  <ftp://rtfm.mit.edu/pub/usenet/news.answers/     faq/enhanced-IDE/>     You can also get it by e-mail from pieterh@sci.kun.nl by sending a     message with "EIDE FAQ text" in the Subject: header. The body of     the message will be ignored. You can replace "text" by "PostScript"     or "html" if you want something more fancy than plain text.     Anything else will probably break the mail server and cause it to     send you an uuencoded coredump :-)     DISCLAIMER.        The information in this FAQ comes without any warranty. The        authors or distributor will not accept responsibility for any        damage incurred directly or indirectly through use of the        information contained in this FAQ.     COPYRIGHT.        This document is copyright (c) John Wehman and Peter den Haan.        You are free to distribute it by electronic means and make as        many copies as you want on electronic or magnetic media, convert        it to a different format, and embed control sequences, as long        as the text of this document remains unmodified, with copyright        notices intact. Splitting up this document is allowed on the        condition that the resultant parts are presented as a        recognizable whole that makes up the full, unmodified text.  You        are allowed to make paper copies of this document for personal        use; however, distribution of printed copies for profit is        prohibited without the authors' prior permission.     THANKS.        To everyone oncomp.sys.ibm.pc.hardware.storage for        encouragement and feedback, especially those who took the time        to communicate their comments in some detail. To Hale Landis        without whom the FAQ would have been considerably less accurate        on a number of key points; to Stephanie Brady from OnTrack for        extensive Disk Manager related information; to Aron Eisenpress        for critically reading the FAQ time and again; and many, many        others.     TODO.     o  Drop the definition of megabyte as 1048576 bytes, which is        nonstandard in this context, and use 1000000 byte MBs instead.     o  Reorganize the FAQ, with a complete overhaul of the text.     o  Write howto type documents walking through specific tasks.     o  Tweak the HTML output more. Perhaps find another translator.     NOTE.        The text, PostScript and HTML versions of the FAQ are all        produced from a common linuxdoc-SGML source. This solution is        not perfect and all versions do contain some infelicities.        Apologies.  Suggestions for improvement are most welcome, as are        complimentary copies of more professional multi-format authoring        tools.  2.  Introduction  The aim of this introduction is to make you familiar with the most  important buzzwords used in this FAQ and to provide a concise overview  of the issues involved. To get the most out of the information in the  FAQ proper, start here.  2.1.  EIDE and Fast-ATA! The IDE field has seen a great number of changes since a few years! ago. These novelties are commonly known under the names Enhanced IDE! (EIDE) and Ultra-ATA. EIDE has caused a lot of confusion since it is! merely a marketing program from Western Digital which, in turn, builds! on a couple of real standards: ATA-2 and ATAPI. Fast-ATA, launched by  Seagate and endorsed by Quantum in response to WD's marketing is! similar. It builds on ATA-2 only. Ultra-ATA is a widely supported! extension of ATA-2 (and ATA-3) adding high speed DMA modes.  2.2.  IDE and ATA  IDE (Integrated Drive Electronics--or numerous other interpretations)  and ATA (AT Attachment) are one and the same thing: a disk drive  implementation designed to integrate the controller onto the drive  itself, thereby reducing interface costs, and making firmware  implementations easier. This low cost/easy integration created a boom  in the disk drive industry, as PC integrators readily ate up the low-  cost alternative. Since the late 80's, ATA (as it is properly called)  has become the drive of choice for the cost inhibited buyer.  2.3.  ATA-2  When it became clear that improvements in harddrive technology and the  increasing demands made by software would eventually strain the  capacity of the ATA interface, the drive industry, in the form of the  Small Form Factor (SFF) Committee, created a compatible extension of  ATA called ATA-2. This standard not only adds faster PIO modes and DMA  modes, but also improves upon Plug'n'Play and compatibility with  future revisions of the standard.  While there is also a new way of addressing sectors on the harddisk  (LBA), this is merely a simplification. Contrary to common myth LBA  proper has nothing to do with breaking the famous 504MB (528 million  bytes) barrier. In fact, even in the old ATA/IDE standard the capacity  limit is well over 100GB.  2.4.  ATA-3  The latest revision of the standard is ATA-3. Key features include:  improved reliability, especially of PIO mode 4; a simple password-  based security scheme; more sophisticated power management; and Self  Monitoring Analysis and Report Technology (S.M.A.R.T.), allowing the  drive to warn you about certain types of impending failure.  ATA-3 does not define any faster modes. Even though some manufacturers! were once marketing "mode 5" equipment, there will never be a PIO mode! beyond ATA-2 PIO mode 4.  2.5.  ATA Packet Interface  One of the disadvantages of ATA is that it was designed for harddisks  only. That was fine back when a high end PC shipped with just a floppy  drive and a 40MB harddisk, but today CD-ROM and tape drives are  commonplace devices that should preferably run off a single low-cost  interface. The ATA Packet Interface (ATAPI) is a standard designed for  devices such as CD-ROMs and tape drives that plug into an ordinary ATA  (IDE) port.  The principal advantage of ATAPI hardware is that it's cheap and works  on on every PC with an IDE or 'EIDE' adapter.  ATAPI tape drives can  enjoy superior performance and reliability compared to the popular  QIC117 'floppy' tape devices.  Beware that although ATAPI devices plug into the IDE interface, they  differ considerably from an IDE harddisk. Caching controllers and  other intelligent interfaces will not work unless they're ATAPI aware.  Booting from an ATAPI CD-ROM is only possible with the latest BIOSes.  2.6.  Ultra-ATA  Ultra-ATA is somewhat similar to Ultra-SCSI in the sense that it! bridges the gap between the current standard (ATA-3) and ATA-4, which! isn't quite finished yet. Ultra-ATA adds a new, high performance mode:! DMA/33 with 33MB/s bandwidth, twice that of DMA mode 2. It is! supported by Intel's Pentium II chipset, the TX Pentium chipset, the! latest Intel competitors and a few add-on (PCI) cards.  2.7.  ATA-4  Work on the next standard, predictably called ATA-4, has already  started. First and foremost it is a much-needed attempt to merge ATA-3  and ATAPI into one. Faster transfer modes are also on the agenda, of  course: it will incorporate Ultra-ATA's DMA/33, at least.  Regarding other features, the future for strong command overlap looks  rather bleak: the current proposal is a hideous animal and important  players like Microsoft do not plan on supporting it in its present  form. More limited forms of overlap stand a somewhat better chance of  surviving.  2.8.  The Enhanced BIOS  A rather different issue was the 504MB (or, equivalently, 528 million  bytes) capacity limit that becomes apparent when accessing IDE drives  through the BIOS. It is caused by the disk geometry (cylinders, heads,  sectors) supported by the combination of an IDE drive and the BIOS'  software interface ('int13').  Both IDE/ATA and the BIOS are capable  of supporting huge disks, but their combined limitations conspire to  restrict the useful capacity of the drive to 504MB. Since only MSDOS  still uses the BIOS for harddisk access, this is sometimes erroneously  thought to be an MSDOS limitation; other operating systems experience  the same restrictions at boot time though.  An Enhanced BIOS works around this problem by representing the drive  to the software using a different geometry than the native geometry of  the drive itself. This juggling act is called 'translation'.  For  example, if your drive has 1500 cylinders and 16 heads, a translating  BIOS will make software programs think that the drive has 750  cylinders and 32 heads.  You do not need an "EIDE" adapter to use harddisks greater than 504MB.  The de facto standard is described in the Microsoft/IBM "INT 13  Extensions" document. Phoenix has presented a superset in their  "Phoenix Enhanced BIOS" specification. Phoenix, AMI, Award and MR  BIOSes are based on the Microsoft/IBM specification.  2.9.  The secondary port and beyond  Last but not least, the usual limit of two devices was far too  restrictive if CD-ROMs and tape drives were to be connected to the IDE  interface in addition to the harddisk(s). Fortunately the solution was  already known in the form of a so-called secondary harddisk interface.  The possibility of such an interface has been there for a long time,  but support was lacking.  There is nothing special about a secondary channel; it is an ordinary  (E)IDE port that uses a different interrupt and I/O addresses to avoid  clashes with the ordinary (primary) one. A secondary interface allows  you to connect another ribbon cable with two more ATA devices  (harddisk, ATAPI CD-ROM or ATAPI tape).  Today, many interfaces  combine both primary and secondary port on a single board to make a  dual-ported interface that handles up to four devices.  To use harddisks on the secondary port with DOS and Windows 3.x, you  will need BIOS (either system BIOS or adapter BIOS) or driver support.  You can recognize a BIOS with four drive support by the fact that it  allows for four sets of drive parameter in the BIOS setup.  There are two further (semi-)standard channels beyond the secondary  port: the tertiary and quaternary ones. Some soundcard IDE interfaces  can be configured as tertiary or quaternary. See section 10.4 for the  I/O and IRQ assignments.  Software support for these is still rare.  3.  General questions  3.1.  What are the main features of EIDE and Fast-ATA?  The fast transfer modes (PIO modes 3 and 4, multiword DMA modes 1 and  2) are the cornerstones of Fast-ATA and EIDE. These are marketing  terms contrived by disk drive manufacturers.  Enhanced IDE is a  Western Digital trademark; Fast-ATA is a term coined by Seagate, and  endorsed by Seagate and Quantum.  EIDE consists of:  o  Fast transfer modes: PIO mode 3 or better, multiword DMA mode 1 or     better,  o  LBA mode (explained in section 10.7),  o  Four devices on the ATA interface: secondary port,  o  No 504MB limit with DOS: WD Enhanced BIOS,  o  tape backup and CD-ROM devices on the ATA interface: ATAPI.  Fast-ATA and Fast-ATA-2 embrace:  o  PIO mode 3 (and 4 for Fast-ATA-2), multiword DMA mode 1 (and 2 for     Fast-ATA-2),  o  Read/Write multiple commands (also known as block mode; see Q10.6),  o  LBA mode.  The difference between the two schemes is mainly in the scope of EIDE.  Hardware can be tagged 'EIDE' even if only part of the EIDE feature  set has been implemented, which can lead to some confusion.  This FAQ  will avoid the term EIDE whenever possible, discussing its component  parts (ATA-2, ATAPI, etc) instead. This allows you to see exactly what  'EIDE' features you need in your specific situation.! 3.2.  What are the main features of Ultra-ATA?!! To everything EIDE has on offer, Ultra-ATA adds the following:!! o  Even faster transfer modes, most importantly DMA/33 with double the!    bandwidth of DMA mode 2 and PIO mode 4. There are no new PIO modes.!! o  Improved reliability using DMA/16 and DMA/33. A checksum is added!    to the data sent over the ATA interface.  That way, data corruption!    can be detected and the data retransmitted.  On an ordinary EIDE!    interface you wouldn't notice the corruption until it was too late.!! Ultra-ATA was first proposed by Quantum and is widely accepted now.!!! 3.3.  Are those rumors about buggy interfaces true?  Very true, unfortunately.  This FAQ doesn't really deal with specific interfaces, but two very  popular interface chips have been shown to contain bugs too serious to  ignore:  o  the CMD640x, a dual-channel PCI to EIDE interface used on many     mainboards (Intel!) and interface boards, has a number of dangerous     bugs you need to be aware of.  o  The PC-Tech RZ-1000, used on AT&T, Dell, Gateway and Intel boards,     also has two data-corrupting bugs. See also     <http://www.intel.com/procs/support/rz1000/index.htm>.  In both cases, the corruption occurs only in specific software  environments and is very subtle; you can go on working for months  without suspecting anything more than buggy software. The damage can  be immense. For all the details, look at Roedy Green's (roedy@bix.com)  "PCI EIDE controller flaws" FAQ included with his EIDE test  <ftp://garbo.uwasa.fi/pc/diskutil/> program which will  test your system for the bugs.  BE WARNED that you're playing Russian roulette with your data if you  continue working on an affected machine without taking notice of this  problem.  3.4.  What is a megabyte?  The word "mega" is an ISO prefix designating a factor 1,000,000.  A  proper megabyte is 1,000,000 bytes. Because computers use binary  technology and like working with powers of two, 2^20 bytes, that is  1048576 bytes, is also usually referred to as a megabyte.  Which of the two types of megabyte you're dealing with depends on the  context. For storage devices, a megabyte usually means 1,000,000  bytes. Some software uses "binary" megabytes, though, and will show a  smaller capacity than the drive label says! This includes most BIOSes.  This FAQ uses megabytes of 1048576 bytes throughout.  4.  Before buying...  4.1.  What should I look for in an ATA-2 (Fast-ATA, EIDE) interface?  There are a number of 'EIDE' features which can be desirable in a new  interface. Some features, however, may already be present on your  system or be unimportant to you.!! o  The least a modern interface should provide is PIO mode 3 transfers     (up to 11.1MB/s) for drives that support it. It should also be able     to use slower PIO modes (0, 1 and 2) to ensure compatibility with!    older drives.!! o  True direct memory access (DMA) is found mostly on interfaces!    integrated into mainboards, Intel 430*X based boards being the most!    common example. This will improve system performance in!    multitasking operating systems. Ultra-ATA will give you DMA/33,!    which actually isn't all that much faster but a lot safer for your!    data.  o  Since ATAPI CD-ROMs have rapidly become very popular in the low-end     market, and ATAPI tapestreamers are similarly taking off, a     secondary port allowing you to connect a total of four ATA* devices     is hardly a luxury. Note that a few modern soundcards provide a     secondary or tertiary ATA/IDE interface instead of the traditional     proprietary CD-ROM connectors.  Beware of conflicts in combination     with a dual-ported interface.     If you intend to connect harddisks to the second port and use them     with DOS or Windows 3.x, remember that many older BIOSes have no     support for the secondary channel and many interfaces do not ship     with the required drivers.  o  You will want an on-card Enhanced BIOS too if your mainboard BIOS     doesn't support translation or if its support is buggy or outdated.     The interface BIOS will override the mainboard BIOS' harddisk     routines.     A BIOS ROM will, just like a mainboard with integrated EIDE, often     have the added advantage that you don't need separate DOS drivers.     The BIOS on an interface will occupy 8 to 16k of UMB space, though,     and you will still want drivers for every other operating system     you use.  o  Drivers! Without well-designed drivers most interfaces could as     well be old-fashioned ISA cards for all the good they'll do. Even     if the card has a BIOS, which usually removes the need for a driver     under DOS, you will still need drivers for other operating systems,!    including Windows and Win95. Newer versions of Windows (Win95 OEM2!    and beyond) ship with a large amount of drivers.! Note that some 'EIDE' interfaces which used to be popular were! slightly to very buggy. This ranged from minor problems with ATA-2! compliance to obscure things like the use of a single buffer for both! primary and secondary channel or a badly designed prefetch buffer,! both of which may cause data corruption under very specific! circumstances.  4.2.  Is my BIOS Enhanced?  How can I recognize this?  Good question.  Unfortunately, I know no easy answer. The mere ability to specify more  than 1,024 cylinders in the BIOS setup is not conclusive. In your BIOS  setup, drive related settings like "LBA", "ECHS" or even something  silly like "Large" are telltale signs of a BIOS with translation  support, which should be good for disk capacities of up to 8GB. A  copyright before 1994, on the other hand, reduces your chances to  something close to zero :-(  o  For AMI, I only have reliable information on their HiFlex BIOS; it     can be recognized by its characteristically funky orange and green     color scheme. There at least two other types: WinBIOS with a     Windows like interface, and a custom BIOS used with Intel Pentium     boards.  Both may translation even if they have a (much) earlier     copyright. I have no further information on those.     AMI HiFlex BIOSes dated 7-25-94 and later and support translation.     The date is embedded in the long number displayed at the bottom of     the screen on bootup; it must be 072594 or later to support LBA.     40-0100-00101111-111192-486-ABC-F  (111192 will not support LBA)     50-0100-001292-00101111-072594-ABCDEF-F  (072594 will support LBA)  o  Award seems to call all its BIOSes 4.50G :-) Some have translation     support, some don't, some have buggy support (see 8.2). With a BIOS     dated 12/31/1994 or later you have full translation support, with     one dated earlier (7/29/1994, perhaps earlier than that as well)     buggy support only.  o  Phoenix BIOS v4.03 and later are reported to support translation.     Some revisions of Phoenix v4.03 may not support it, though,     depending on the computer or system board manufacturer.  o  MR BIOS incorporated CHS translation--roughly the same as today's     Large mode--as early as 1990!  Note that only BIOSes fully implementing the IBM/Microsoft/Phoenix  standards will allow access to disks larger than 8GB. Fortunately,  these are becoming more and more common these days. We are not aware  of utilities that will detect the presence of such a BIOS.  Western Digital has a utility available by ftp that examines the  Enhanced Disk Parameter Table (EDPT), if present. If it finds one on  your system, your BIOS has all the bells and whistles to go up to 8GB  <ftp://ftp.wdc.com/drivers/hdutil/>. Beware that BIOSes  conforming to the WD Enhanced BIOS specification won't build an EDPT  unless LBA is enabled. Beware also that with a WD EBIOS it is highly  unsafe to enable LBA on a disk that already contains data. This is due  to a flaw in the specification.  4.3.  Is my 50MHz VL bus system compatible with ATA-2 interfaces?  It should be, but there are problematic cases.  It has been observed that some controllers will base their I/O cycle  times on the bus clock of the computer. This means that with a 50MHz  bus, the cycle time will be faster than with a 33MHz bus. This could  lead to undesirable results if these cycle times are faster than the  drive can handle. Make sure your controller supports multiple bus  speeds in the software setup, and if necessary program it correctly.  4.4.  Are old IDE drives compatible with EIDE and U-ATA interfaces?  This should work fine.  Older drives do not support the high-speed advanced transfer modes! defined by ATA-2 and, later, Ultra-ATA. To retain compatibility with! these drives, ATA-2 and Ultra-ATA interfaces have programmable timing.! The driver or BIOS queries the drive regarding its maximum transfer! rate and will configure the interface to match. A few interfaces are! jumper configurable in which case the responsibility is yours.  If you intend to put an older drive on the same cable as an ATA-2  drive, you may want to verify that your interface is capable of using  independent timing for master and slave device. Otherwise, your old  drive might end up slowing down your newer one because the controller! is forced to use the lowest common speed. Modern interfaces like the! Intel PIIX3 (430HX and VX and 440FX chipset), PIIX4 (430TX chipset)! and, to a lesser extent PIIX (430FX chipset) don't suffer from this! problem.  4.5.  Can I use EIDE and U-ATA drives with my old (E)IDE interface?  Fast-ATA and EIDE devices can be used without fear on regular ISA or  VLB IDE controllers. The thing about advanced modes is that the drive  is ready for the data in the fastest mode; the slower the controller,  the easier it is on the drive. Of course you should expect the  transfer rates to come out lower than on a full ATA-2 interface.! Likewise, an Ultra-ATA drive will do fine on an ATA-2 (EIDE)! interface. Better even, using DMA mode 2, its performance will be! hardly any slower than it would be on an Ultra-ATA interface.!  It is not necessary to use an EIDE interface for harddisks of over  504MB.  An Enhanced BIOS is all you need for DOS and Windows; for many  other operating systems such as OS/2 or Linux you won't need even  that.  4.6.  Will an ATAPI (EIDE) CD-ROM work with an IDE interface?  Yes. These devices were designed to be compatible with ATA (IDE) from  the very start, and should work fine.  4.7.  Do I need a BIOS update to connect an ATAPI CD-ROM?  No. These CD-ROMs ship with a driver that provides complete support.  The BIOS doesn't need to support them and usually doesn't even know  they're there. Some modern BIOSes are ATAPI aware and have a special  setting; barring those, you can generally leave the corresponding  harddisk entry at 'Not Installed'.  4.8.  Can large drives be used with my old BIOS?  Yes, in principle, but there's still the small matter of the 504MB  barrier. If the new drive exceeds this capacity, you must have an  Enhanced BIOS in order to use more than 504MB with DOS, Windows or  Win95 (see Q4.10 for other operating systems). It is important to note  that this is a software only issue: you do not need a special  interface to support large drives.  BE WARNED that some older BIOSes will incorrectly handle drives with  more than 1024 cylinders. Instead of truncating the number of  cylinders to 1024, they use the cylinder count modulo 1024, which  means that a 2300 cylinder drive will appear to have just 252  cylinders. The solution is to specify 1024 cylinders in the BIOS  setup.  This becomes a real problem when a BIOS with this error also won't  allow you to enter the drive parameters manually. Among IBM systems,  the 1991-vintage PS/2 models 35sx and 40sx, the ValuePoint I, and at  least some of the ValuePoint Si models have this flaw. With these  machines, you should either try go get a BIOS upgrade from  <ftp://ftp.pcco.ibm.com> if you have a flash BIOS, or verify that the  drive you intend to use has a way to fake having no more than 1024  cylinders (Western Digital has a utility for their 540MB drive, and  many Maxtor drives have a jumper). The Promise EIDEMax is also  reported to work, and will allow you to use drives of up to 8GB in  full. Note that some operating systems, such as Linux and OS/2, allow  you to override the BIOS' drive geometry information, which may also  help addressing this problem. Another option is using OnTrack Disk  Manager version 7.  4.9.  I need an Enhanced BIOS to access >504MB. How do I get one?  The options are: a new mainboard BIOS, add-on BIOS, or software.  o  To upgrade your mainboard BIOS, either with a newer version of your     current BIOS or using a custom made BIOS from firms such as Microid     Research (MR BIOS), is probably the best option. It may or may not     be more effective to replace the entire mainboard and get all the     latest bells and whistles for $100 more.  o  The next option is to purchase a card with an add-on BIOS that     effectively replaces the harddisk portion of your mainboard BIOS.     An example is LBA Pro from Storage Technologies, sold in the USA by     Unicore software, or AMI's AMIDisk Extender. DataTechnology (DTC)     also sell such a card.  o  Most BIOSes on ATA-2 interfaces, if they have a BIOS at all, also     do this. That may be a nice way to go if your present interface     isn't up to snuff. For the ISA bus, there are a few "EIDE"     interfaces that have a BIOS: examples are the Promise EIDEMax and     the SIIG IDE Enhancer.  Either way, you will have to repartition and reformat the (large)  harddisk.  o  A final option is to use a software solution, like Disk Manager or     EZDrive. Software is often supplied free with the drive and     relatively easy to install, but has inherent drawbacks. See also     Q6.8.  4.10.  Can I use a large harddisk with OSs other than DOS/Windows?  Using a large harddisk is usually no big problem, even if you don't  have an Enhanced BIOS. However, some OSs don't understand translation,  which makes the combination with DOS, Windows and Win95 problematic.  With operating systems such as NetWare, Unix, Win/NT and OS/2, the  only thing you need to use large ATA disks is a BIOS that allows more  than 1024 cylinders in the drive type setup.  There is one caveat  though: the BIOS is still used to boot the operating system, so you  will have to ensure that everything necessary to get the OS running in  the first place resides below cylinder 1024. Remember that if you have  an Enhanced BIOS, drives up to 8GB will appear to have no more than  1024 cylinders, so in those cases these boot restrictions are removed.  Once running, these operating systems use their own software to  control the disks (Win95 also does this, but has a special position;  see below). That way, they are not subject to the BIOS' restrictions  such as the capacity limit.  Unfortunately, this also means that if  you have a translating EBIOS or software driver, the OS has to be  aware of the translation scheme used, or conflicts will arise between  the operating system and DOS/Win/Win95. If you can set up partitions  so that all DOS and boot partitions reside below the first 1024  cylinders (504MB), you can avoid translation altogether and all the  hassles with it.  Older operating systems don't understand translation at all. Newer  ones (OS/2 3.x, Linux 1.2 or better, Win95, SCO 5.0.x) will handle  standard translation schemes out of the box, but not always those  employed by some software drivers (EZDrive, Disk Manager v6.x or  older). In the case of DM 6, fixes or updates are available for some  operating systems (see above).  Novell has a NetWare driver IDE.DSK version 3.0 dated September 2,  1994. This version of the driver uses the Identify Device ATA command  to get the drive parameters and ignores the BIOS parameters. This  means that Novell now works with big IDE drives.  A final remark: OS/2 enforces DOS compatibility for FAT partitions.  That means that without an Enhanced BIOS, only HPFS partitions can  extend beyond cylinder 1024.  4.11.  I heard that Win95 provides support for large IDE disks.  True, but it doesn't necessarily mean you can actually benefit from  that support in all cases.  Despite a large number of significant changes, in its way of handling  harddisks Win95 largely resembles Windows for Workgroups. Just like  OS/2, Linux and other operating systems, Win95 uses 32-bit protected  mode drivers for the harddisks (unless it's using compatibility mode),  and is happy to handle harddrives of respectable size: well over  100GB. However, unlike OS/2 and Linux, and like Windows for  Workgroups, Win95 boots from the same old DOS we all love to hate.  Even once Win95 has booted, DOS hasn't gone. Win95 always keeps it  behind the scenes and uses it to run devices in compatibility mode. In  'safe mode', important for troubleshooting, Win95 completely relies on  DOS.  What all of this implies is that even though Win95's protected-mode  disk driver may support gargantuan drives, it will never change the  setup it inherits from DOS in order to retain compatibility with the  latter. If you can only get at the first 504MB of your drive in DOS,  it will be the same in Win95. You will still need one of the usual >  504MB solutions mentioned elsewhere in this FAQ. For details, see also  Microsoft KnowledgeBase article Q126855, "Windows 95 Support for Large  IDE Hard Disks".  4.12.  Can I use more than 2 or 4 hard drives?  For DOS and Windows you probably want BIOS support for all your  harddisks. Older BIOSes support drives on the primary channel only,  just two; newer ones add support for the secondary channel for a total  of four. Few BIOSes support more than that; MR BIOS is an exception.  If the BIOS supports just two drives and you want more, there's a  software solution available: 3drives (see the net.resource guide).  Some interface cards also ship with the necessary support. Creative  Labs has drivers for CD-ROMs on the tertiary and quaternary port.  Other operating systems such as Win95 and OS/2 support both primary  and secondary interface without aid from the BIOS. Linux will support  a nearly arbitrary number of interfaces; you'll have to pass kernel  parameters to specify the ones beyond the first two.  4.13.  Does <insert operating system> support ATAPI (IDE) CD-ROMs?  The current versions of most operating systems support ATAPI CD-ROMs.  That includes OS/2 3.0, Linux 1.2 and above, and Win95.  Unfortunately, hardware manufacturers have started designing these CD-  ROM units while the ATAPI standard was still evolving, so there are  now a couple of versions implemented in the real world. Moreover, the  complexity and novelty of ATAPI means that there are some variations  even among implementations of the same revision. Writing an OS ATAPI  driver that works with all CD-ROMs, therefore, is a daunting task and  not all have succeeded equally well. So although these OSs all support  ATAPI, they do not work with all ATAPI equipment.  See Microsoft KnowledgeBase Q131499, "CD-ROM Drives Requiring Real-  Mode Drivers", for more details on Win95 support. For OS/2, take a  look at  <http://www.austin.ibm.com/pspinfo/os2hw.html>; for updated  drivers use the latest install disk upgrade or  <ftp://ftp.pc.ibm.com/pub/os2_drivers/atapi.zip>.  4.14.  I need a PCI ATA-2 interface that uses only one slot.  There is a problem with PCI and multi-I/O or dual-ported IDE  interfaces. Such interfaces need two or more predetermined interrupts  which cannot be shared with other PCI devices, which is probably  impossible with your PCI slots. The usual workaround consists of  either integration of I/O functions on the mainboard, or the use of a  tiny 'paddle' board that plugs into an ISA slot.  This is not so much a weakness in the design of PCI, but a conflict  between PCI's plug'n'play philosophy and the requirement that these  interfaces be fully compatible with oldfashioned I/O cards.  Some vendors use PCI interfaces that rely on a proprietary extension  of the PCI bus. This is obviously not portable; you often can't even  move the card to a different slot in the same machine. Moreover, such  extensions may cause compatibility problems since they use PCI signals  reserved for other purposes.  4.15.  Will adding an Ultra-ATA interface help my drives' performance?  A new interface may or may not help; it is possible to make a rough  prediction if a better interface would really speed things up.  Hardware vendors and marketing people would love to see everyone rush! out and buy the latest generation of 'Ultra-ATA' adapters. To achieve! this noble goal they tend to juggle with too-good-to-be-true! performance figures. The relation between this advertising hype and! the real world is shaky at best.  The main point to remember is: a slow drive is a slow drive no matter  how good the interface is. If the speed at which the drive physically  transfers the data to/from the media is the limiting factor in  performance, and it often is, the only way to make things go  significantly faster is to purchase a better drive. Note that the! transfer modes supported by modern drives (those 33MB/s figures) have! little to do with their real-world performance.! In addition, an 'ordinary' ATA-2 (EIDE) interface already offers! respectable bandwidth---the fastest ATA-2 transfer mode is! theoretically 16.6MB/s, which is more than any Ultra-ATA drive on the! market today can sustain. In addition it usually supports the CPU-! cycle-saving DMA modes. An IDE interface, on the other hand, makes a! much better candidate for replacement since it rarely has a bandwidth! over 2.5MB/s, which is cramped by today's standards, and doesn't! support DMA.  How to determine if the drive is the bottleneck? You can get a rough  idea using Coretest version 3 <ftp://ftp.rahul.net/pub/lps/  disk/core303.exe>. This version of Coretest gives two performance  figures of interest here: the (B)uffered transfer rate which is an  indication of the bandwidth between drive and interface, and the  (S)ustained rate which is related to the speed of the drive media. If  your drive has a small buffer cache, you may have to use the /B16  option to get the correct buffered transfer rate.  Usually you'll find that the first figure exceeds the second by a  considerable margin (say, a factor two or more). This means that the  physical properties of the drive itself are the bottleneck, and  improving the interface speed any further won't help much. The only  thing that may improve performance somewhat is using block mode (using  either a BIOS option or a driver).  Only if the drive throughput  starts to approach the interface bandwidth will you have a fair chance  that a new interface will have a large impact on performance, provided  the drive supports faster modes than the one currently used.  This is not an endorsement of Coretest as a disk benchmark; there are  more reliable ones around, such as QBench  <ftp://ftp.rahul.net/pub/lps/hard-disk/>.  Be sure to read question 7.2 to get a more complete picture.  5.  Installation  5.1.  Which drive/device should be Slave?  o  A single device on a cable, either a harddisk (ATA) or CD-ROM     (ATAPI), should according to the specs never be configured as     slave. However, as any ATAPI CD-ROMs come preconfigured as slave,     most software works with a masterless slave CD-ROM simply because     it saves tech support calls. Moreover some BIOSes have trouble with     an ATAPI device jumpered as master. Formally it isn't a valid     configuration though; remember this if you have trouble getting the     CD-ROM recognized.  o  Two harddrives on one channel should be configured as master and     slave, respectively. It usually doesn't matter which is which, but     older harddisks may not work in all configurations if they predate     the standardization of the master/slave protocol. In that case a     degree of experimentation will be necessary. Some Conner drives     have an ATA/ISA jumper: ATA is the now-standard protocol, ISA is     used by older Conners.  o  Two ATAPI devices such as CD-ROMs and tapes should work fine as     long as one device is master and the other slave, just like     harddrives.  o  If you need to put a harddisk and an ATAPI device on the same     cable, the spec says the harddisk must be the master. Although the     reverse will usually work as well in practice, still you'd better     avoid the configuration.  5.2.  Does it matter how I connect the devices to the cable?  Not much. If you have only one drive on the cable, it is best to put  it at the very end, especially when you're using any of the faster  modes. For two devices, it doesn't matter where you put the master and  the slave, or which end of the cable you plug into the controller.  Just take care that you plug them in the right way: the red wire is  supposed to correspond to pin 1.  When Plug'n'Play ATA arrives the Cable Select (CS) setting will be  used, and all of this will change. Some name brand machines may  already employ a similar setup.  5.3.  Does an old HD or CDROM slow down a new drive?  This is not necessarily the case. Still, it is generally preferable to  connect older drives and CD-ROMs to the secondary channel.  If this is not feasible, or if you're wondering if you should upgrade,  a few points.  o  The speed loss usually referred to is in the interface timing, i.e.     the speed at which the devices communicate with the computer. This     does not necessarily translate into a real world performance     penalty.! o  This is mostly an issue with older ATA-2 (EIDE) interfaces and some!    VL IDE ones. If you have an ordinary ISA IDE interface, it can't!    get any slower.! o  All modern interfaces support distinct timing for master and slave.!    With these, the slow device does not directly affect the fast one.! o  Many CD-ROMs support at least PIO mode 3. This is enough to operate!    most harddisks on the market today near their maximum speed.     You can use Coretest <ftp://ftp.rahul.net/pub/lps/     disk/core303.exe> to determine if and how performance is affected;     see Q4.15 for a recipe.  OS/2 and Unix users have another reason to put slow ATA devices such  as tapes and CD-ROMs on a channel of their own. As long as one unit on  a given channel is executing a command, the other is inaccessible. A  CD-ROM can easily occupy the channel for 300ms that way.  5.4.  I need a longer IDE cable; how long can I make it?  Less than 18 inches. In some cases, the limit is no more than 7  inches.  The cable is a pretty weak link in the whole ATA-2 interface. For the  fast transfer speeds used in 'EIDE' systems, there aren't enough  ground signals; the cable is unterminated and unshielded. Noise is a! real problem. All of this applies to ATA-2 (EIDE) systems more than! Ultra-ATA systems, since the latter use checksums to ensure data! integrity.!! For those reasons, you should take the 18" limit specified by the! ATA(-2) standard pretty seriously if you want to avoid data corruption! and system hangs.  Even worse, some dual-channel 'EIDE' interfaces! such as CMD640x based ones have a peculiar design employing only a! single buffer for both cables. Most signals on the two cables are! directly connected with each other: this means that electrically, the! cable lengths add up. Take into account that the copper traces on the! circuit board are often a couple of inches long as well and you're! facing a maximum cable length of roughly 7" per cable if you want to! remain within spec.  If you have difficulties fitting everything in with a standard length  cable, consider adding a new plug to it or rolling a complete cable  yourself. It's not hard to do, or to track down a friend willing to do  it, and you can buy the parts in all electronic parts stores. Do use  quality parts, work carefully, and watch that length.  Disregard the above at your own peril. Noise induced problems usually  pop up sporadically, can be very hard to detect and even harder to  track down. Not least because they may appear completely unrelated and  involve devices other than the harddisk.  5.5.  Can I safely move my harddisk between computers?  Transferring a partitioned and formatted harddisk between computers is  potentially dangerous if they use different translation schemes (see Q  6.3). This includes moving a disk from an old computer that doesn't  support translation to a new one that does. This is really a little  known issue.  Usually everything goes smoothly, but you would not be  the first to be caught by surprise.  WARNING. Do not assume it won't happen to you just because it works  out fine most of the time---it has destroyed data, and will do so  again.  6.  Configuration  6.1.  Should I use my interface's device drivers?  Yes. Often these drivers are essential to get any kind of performance  out of your interface.  The PIO or DMA mode used when transferring data is determined by the  interface card. Some cards have jumpers that determine the speed in  hardware; these work in the fast mode from the microsecond you switch  on the computer.  Most interfaces, however, are software configurable. At bootup, they  default to the slowest possible speed. Somewhere during the boot  process, a piece of software belonging to your adapter figures out  what kind of transfer rates the drives support and configures the  controller chip to match. There are a couple of cases to distinguish:  o  Onboard I/O with full BIOS support. The controller is fully     configured when your computer boots. You can usually set the     desired mode for each harddisk in the CMOS setup. Many modern     boards fall in this category.  o  Onboard I/O with incomplete BIOS support. For some unfathomable     reason, some mainboards do not support or only imperfectly set up     their integrated I/O ports.  In that case, you'll have to use DOS     or other drivers to get full functionality.  o  Interface card with BIOS. This is similar to the two categories     above. The main difference is that these cards don't necessarily     have setup screens; in that case, they must use other means to     determine the transfer mode to be used. For example, the Promise     2300+ uses a combination of jumpers and a table in ROM containing     the parameters for a number of different drives. It may or may not     be necessary to use drivers for best performance.  o  Interface card without BIOS. Since there is no way the mainboard     BIOS can know how to set up all those different interface cards out     there, you must use the supplied device drivers to profit from the     fast modes. That is, unless your card is hardware configurable     using jumpers, which is quite rare.  Usually, there are drivers for other operating systems as well, such  as Windows, Win95, OS/2 and so forth. These serve a couple of  purposes.  o  The driver may be necessary to configure the adapter as described     above. This doesn't apply to Windows, where the DOS device driver     usually has already done that job.  o  The standard drivers built into operating systems don't support all     of the advanced features of your interface and drives. Examples are     32-bit transfers, block mode and DMA.  o  Windows only: the standard driver (*wdctrl) that ships with Windows     and Windows for Workgroups has some serious restrictions. See Q8.10     for details.  In view of this it is rather unfortunate that so often, the drivers  supplied with an interface are of mediocre quality.  6.2.  What should I use: Normal, LBA or Large?  The difference between the three is this.  o   'Normal' causes the BIOS to behave like an old fashioned one     without translation. Use this if your drive doesn't need it (ie.     has fewer than 1024 cylinders) or if you want to use the drive with     an operating system that doesn't understand about translation.  o   'Large' or ECHS or XCHS tells the BIOS to use CHS translation. It     uses a different geometry (Cylinders/Heads/Sectors) when accessing     the drive than when talking to the software through int13. This     type of translation works with all drives.     Note. Some BIOSes have a braindead Large implementation which works     only for disks of up to 1GB. Fortunately, all larger disks support     LBA.  o   'LBA' differs from 'Large' in that it uses LBA addressing to     access the harddisk. The advantage is that it theoretically is a     little faster. The disadvantages are that some older drives don't     support it, and it often turns out to be slower, depending on the     drive.  WARNING. Some BIOSes change the (translated) geometry if you change  from Normal or Large to LBA. The same thing may happen if you transfer  a disk that has been formatted on an old, non-LBA computer to a new  one that uses LBA. This has destroyed data. Don't let it happen to  you.  Section 10 tells more about the differences between these three.  6.3.  Can I safely change the BIOS' xlation mode (None, LBA, Large)?  Unfortunately, no. Proceed with care.  While with many BIOSes, the sectors on the disk are addressed in the  same order independent of the translation mode, a few use a different  type of translation algorithm. The latter type of BIOS will shuffle  your data as if it were a deck of cards if you alter the translation  mode.  Moreover, BIOSes that conform to the WD Guide may use completely  dissimilar drive geometries in the software (int13) interface  depending on the translation mode. If this happens it will wreak havoc  with your data. This represents a major flaw in the WD EBIOS  specification.  In both of these cases, after changing the translation mode, you must  repartition and reformat your disk.  6.4.  Should I enable EIDE busmastering in my BIOS?  The only reason why you would want to enable this option is that DMA  modes are less likely to corrupt data than PIO modes. There will be no  difference in CPU usage. (when DMA/33 arrives, the improved bandwidth  will be another reason).  Unfortunately, at least one user has reported a drastic decline in  drive throughput with DMA enabled. The reasons are unclear, so YMMV.  6.5.  FDISK sees only 504MB of my disk!  First and foremost, do you have an Enhanced BIOS? See section 2.8 and  Q1 for more details. If you do have an EBIOS, make sure you have  enabled translation: usually, either 'Large' or 'LBA'. If you see no  such options in your BIOS setup, remember that some types of BIOS  offer them only when you tell it to autodetect the drives.  Last but not least, remove all old partitions before trying to create  new ones after changing the translation mode.  6.6.  FDISK will partition only 2GB.  There's nothing wrong; this is a limitation of the DOS FAT and Win95  VFAT filesystems. You will have to create multiple partitions in order  to use the full drive size.  This limitation has been addressed in Microsoft's new FAT32  filesystem, currently only available in the Win95 OEM 2 release. It  allows giant multi-gigabyte partitions. At the time of writing this  release can be sold with new hardware only and is unavailable to  ordinary mortals.  6.7.  I have no fancy EBIOS, but I have an 1GB partition and it works.  Some try to work around the 504MB / 1024 cylinders issue by making a  large partition using a friend's computer, Linux' fdisk, or something  else. They use it for a day or two, conclude that it works, then post  a triumphant article claiming that they found the Solution To  Everyone's Problems[TM].  It will work... for precisely 1024 cylinders. The very moment the OS  or anything else attempts to write something to cylinder 1025 through  int13 calls, the write wraps around to cylinder 0. This cylinder  happens to hold some of the most important data structures on the  disk: the Master Boot Record, partition table, both FAT copies and the  root directory of the first partition. Overwrite these and probably  only a specialized data recovery company will be able to salvage your  data.  Try it if you must. If you know exactly what you're doing, you can  make it work using Win95. Sort of. The first error will be fatal. But  please don't post any stories about it, recommending the procedure to  everyone. The spectres of their valuable data will come back to haunt  you.  6.8.  I have software to break the 504MB barrier. Should I use it?  This is a convenient option, but there are caveats.  The software, sometimes bearing an exotic name depending on the  licensee, is usually a version of either MicroHouse's EZ-Drive or  OnTrack's Disk Manager. Disk Manager, when used on the boot drive, has  to resort to some trickery in order to be loaded very early during the  boot process (which is necessary for technical reasons). This is  accomplished by modifying the Master Boot Record (MBR), the first  piece of code the BIOS loads and executes when the computer boots, and  storing a Dynamic Drive Overlay (DDO) on the very first disk track.  EZ-Drive works in a similar fashion.  An annoying side effect of using a software solution is that operating  system installations, which often overwrite the MBR, will render the  contents of your harddisk inaccessible. You will need to restore the  MBR from the installation floppy to regain access to your partitions.  Moreover, such software tends to create partitions quite different  from 'standard' translation schemes as used by most Enhanced BIOSes.  Many device drivers dealing with the disk will fail even if they work  fine with other schemes. Important examples are (E)IDE interface  drivers; remember that without these drivers an interface will in  general be much slower. You'll need drivers that are specifically  aware of the translation software you use. Also, many operating  systems other than DOS will not be able to access or use the drive, at  least not 'out of the box'. Disk fixing utilities may fail to work if  the partition table or the overlay is damaged.  This also makes it difficult to upgrade to a BIOS based solution.  OnTrack Disk Manager version 7 includes a migration utility for the  purpose and improves on version 6 in a number of other ways. It allows  multiple operating systems and is compatible with most interfaces and  drivers, including those for ATAPI CD-ROMs. Owners of version 6.03,  which is still often included with hard drives, can download an update  patch from OnTrack  <http://www.ontrack.com/pub/software/dmpatch.zip>  that gives some of the benefits of version 7. View  <http://www.ontrack.com/dm.html> for general information.  For older versions of Disk Manager, IBM and Microsoft have fixes for  OS/2 (in FixPak 5 or later, or out of the box in Warp FullPack and  Warp Connect) and NT (Service Pack 2). Win95 should support Disk  Manager and EZDrive out of the box (see Microsoft KnowledgeBase  article Q126855, "Windows 95 Support for Large IDE Hard Disks"). More  about Disk Manager in section 13.1.  6.9.  Can I keep my Disk Manager/EZDrive partition with a new BIOS?  If you have a Disk Manager or EZDrive partition and are upgrading to a  translating BIOS, you have three options.  o  The utility is compatible with LBA translation, or has a migration     feature. This makes for a smooth upgrade path. (I'm only certain     about Disk Manager v7).  o  The above isn't true and you don't want to go through a backup,     repartition, restore cycle. Tell the BIOS to use Normal mode for     the harddisk and the utility should continue to work as usual.  o  Backup, repartition, restore. See 6.10 if you experience     difficulties removing the utility.     Always back up your data before doing a system upgrade.  6.10.  I need to remove Disk Manager/EZDrive.  This software is usually installed in the boot drive's Master Boot  Record (MBR). Normal repartitioning and reformatting of the drive  usually does not refresh the MBR, which can make for a frustrating  experience. Fortunately, it's not very hard once you know how.  The best way to deinstall is to follow the procedure outlined in the  utility's documentation. If this is not available, the following  procedure usually works: boot from a clean floppy with at least DOS,  FORMAT.COM and FDISK.COM on it. Then type FDISK /MBR. This should  refresh the code in your MBR. After that, repartition and reformat as  usual.  For reasons I do not understand, some Disk Manager versions are  reported to cling to life rather tenaciously (perhaps due to  overambitious virus protection by the BIOS?). In that case, you need  DM.EXE. Type DM /Y-. If that fails as well, the following procedure  was reported to work by Mark Brown (mrkbrown@netcom.com).  1. run DM (in this case, v.6.03)  2. press ALT-T  3. select (D)isk Sub-System Overview  4. select appropriate hard drive  5. press CTRL-F10  to clear out the MBR  6. press Y to confirm  7. press ESC to exit out of DM, rebooting from a clean floppy  If you have faced similar situations and can add to this, please share  your knowledge. A good candidate would be a utility that simply zaps  the partition table---any takers?  WARNING. Disk Manager and EZDrive partitions differ from those created  by a translating BIOS. Expect your data to be inaccessible after this  operation. An exception is v7.x of OnTrack's Disk Manager; DM.EXE has  a Migrate feature that works with many BIOSes.  WARNING. Some controllers and security software stores information on  track 0 which FDISK /MBR will clear. In this case, the data on the  disk is lost anyway, but there are a number of circumstances where  this command can destroy data.  6.11.  I can enable write caching on my harddisk. Should I?  Do not confuse this with Smartdrive (or whatever) lazy writes: what is  meant here is altering the drive's buffer cache management algorithm.  This is possible using newer versions of Drive Rocket, with hdparm  under Linux, and probably other utilities too. Provided, of course,  the drive supports this feature. Sometimes it can also be done using  jumpers on the drive.  There seem to be problems with this, if a program will issue a soft-  reset (which on Intel Pentium Motherboards also issues a hardware-  reset) as soon as it sees the last IRQ, which overall ends up  corrupting data. Use with care, and backup.  6.12.  My drive letters have changed!  MS-DOS assigns drive letters as follows.  o  Letters a: and b: are reserved for floppy drives.  o  All primary partitions on all (system and adapter) BIOS supported     harddisks get their drive letters starting from c:, in order.     Normally, you can have just one primary DOS/Windows partition on     every drive.  o  Only then, all logical drives inside extended partitions get their     letters. This means, for example, that if you had one drive with c:     and d:, adding a second drive with one primary partition on it will     bump the former d: partition up to e:. If you want to avoid this,     do not define primary partitions on all drives except the first     one.  o  After that, MS-DOS parses the CONFIG.SYS and AUTOEXEC.BAT files.     Some devices such as CD-ROMs have no BIOS support and get their     drive letters only here.     Remember that some programs, including disk compression software,     may do shuffling tricks with drive letters. Be also warned that     some BIOS setup screens, in a misguided attempt at user     friendliness, refer to harddisk units using drive letters. In     trivial cases, this may be right, but in nontrivial setups the BIOS     may be all wrong.  7.  Performance  7.1.  Why isn't my drive as fast as it's advertised to be?  Good question. The basic answer is that the advertised modes are  theoretical transfer rates.  This is the case at two levels. First and foremost, the oft-quoted  rates do not represent the speed at which the drive can actually read  data from, or write data to, the magnetic media. Instead, they give  the speed at which data can be exchanged between the drive's buffer  cache and the CPU. While the latter gives the more imposing figures,  the former has greater impact on real world performance. "It is really  as if the government had had a speed limit of 250 km/h on the  highways, then raised it to 1600 km/h and tried to impress you by  telling you that now you can drive faster"--Aaron Bilger  (bilgerar@mentor.cc.purdue.edu).  Second, even once you accept that these transfer rates can be achieved  only when the drive happens to have the data ready in the buffer  cache, these figures are pretty optimistic.  Realistically, drives do  more than just give data to the host out of the cache. For each sector  transferred to the host, the drive's controller needs to get one from  the media; internal controller processing, table updates, positioning  and buffer cache management all take some of the controller's  attention. All reduce the throughput from the cache to the host.  On top of that, depending on the benchmark used to determine the  'throughput', the rate can vary from 3MB/s to 30MB/s and upwards, all  on the same drive.  This depends on what the utility actually  measures, how it measures it, and even where on the drive it measures  it (different zones on the same drive can vary up to a factor two in  speed).  Plus, system configuration (MHz CPU, RAM, harddisk cache,  processor cache) make a difference as well.  Bottom line is, whatever benchmark you use, you will not 'see' the  advertised transfer rate. The real test is how well it improves your  day to day applications. The rest is just fluff.  7.2.  Why is my new EIDE, U-ATA interface no faster than my old one?! There are several reasons why it is possible that an Ultra-ATA! interface is no faster than an older one even if the drivers are  installed and everything works properly. The first, and most  important, is that the bandwidth of the fastest ATA-2 mode, 16.6MB/s,  exceeds the real world transfer rate of most drives on the market  today by a considerable margin. If this is the case for your drive,  increasing the interface bandwidth beyond this will have no noticeable  effect.! A further possibility is that your drive does not support the Ultra-! ATA transfer modes at all. In that case, an Ultra-ATA interface may! improve performance relative to an old-fashioned ISA bus or VL bus! interface, but it will be no faster than a good PCI ATA-2 (EIDE)! interface.  7.3.  I benchmarked my drive and it's getting slower!  Believe it or not, but this is completely normal. First, filesystem  fragmentation affects some benchmarks; try defragging the drive.  Second, not all parts of the drive are equally fast.  Physically, a harddrive consists of one or more rotating platters,  where the tracks are concentrical circles on these platters.  Obviously, the outermost tracks are longer than the innermost ones.  Because they are longer, they can hold more sectors. As you work your  way inwards and the track length decreases, the number of sectors  decreases in a number of steps. This is referred to as Zone Bit  Recording (ZBR).  Back to the benchmarks. Since the platter spins at a constant rate,  more sectors in a track give a proportionally higher transfer rate.  The very first cylinder of your drive is right at the edge of the  platter, in the fastest zone. This is the area that was tested when  you got your drive and tried to find out how well it performed. As  your drive fills up, you start using higher cylinder numbers---and  slower zones. Depending on the type of benchmark you use, this may be  reflected in lower scores.  The difference in sectors per track (and hence transfer rate) between  the fastest and the slowest zone may be as much as a factor two.  Typical drives have anything from five to twenty zones, all with a  different number of sectors per track.  7.4.  A guy on the net has the same drive and he gets 33MB/s!       "Usenet is like a herd of performing elephants with diar-       rhea--massive, difficult to redirect, awe-inspiring, enter-       taining, and a source of mind-boggling amounts of excrement       when you least expect it."  -- Gene Spafford (spaf@cs.purdue.edu), 1992  7.5.  Busmastering drivers don't do much...  First of all, busmastering will generally not do much with the  transfer rates themselves. What it does is relieve the CPU from the  chore of shovelling data around, so that it can do something more  useful. However if you tend to do only one thing at a time, or you're  running a benchmark, the extra CPU time can't be used for anything and  busmastering will have no appreciable effect.  Second, you will not see any decrease in CPU usage with the System  Monitor in Win95 because it tracks the amount of time spent in the  "system idle" loop. However, with a pending I/O operation, the system  doesn't spend its spare cycles there, but in the "waiting for I/O to  complete" loop.! Third, you need to use DMA to profit from the improved data integrity! and enhanced transfer rates of Ultra-ATA.!  8.  Troubleshooting  8.1.  Why do I get NO ROM BASIC, SYSTEM HALTED?  This should get a prize for the PC compatible's most obscure error  message. It usually means you haven't made the primary partition  bootable or, in  Microsoft-speak, 'Active'. Use FDISK to fix this.  Don't fret, you won't have to repartition or reformat anything unless  you have no primary partition at all.  The earliest true-blue PCs had a BASIC interpreter built in, just like  many other home computers those days. Even today, the Master Boot  Record (MBR) code on your harddisk jumps to the BASIC ROM if it  doesn't find any active partitions. Needless to say, there's no such  thing as a BASIC ROM in today's compatibles, and this action ends in  the above error message.  8.2.  I have problems with my Award 4.50G BIOS and large drives.  If your 4.50G BIOS is dated earlier than 12/13/1994, the address  translation table is faulty. To access drives with more than 1024  cylinders, you cannot use address translation (Large) but must use  LBA. In versions dated 12/13/1994 or later this has been fixed. Be  warned that switching to LBA will probably force you to repartition  and reformat your drive; do back up your data.  8.3.  My 2GB+ drive is not recognized or crashes.  Many BIOSes dated before 1996 contain bugs making them incompatible  with drives of more than 4096 cylinders, which works out to be about  2GB in size.  Some BIOSes have similar problems at the 8192 cylinder  boundary (4GB). The effects may range from not being able to use the  full capacity to a crashing BIOS during bootup or upon detecting the  drive.  Possible solutions include  o  a flash BIOS update, if you've got a flash BIOS and your board     manufacturer makes a fixed BIOS image available;  o  non-flash BIOS ROM ugrade;  o  a software disk manager like using OnTrack Disk Manager or EZDrive;  o  if the BIOS allows a user definable drive type, manually setting     the cylinder count to 4095 (8191). This means you can use no more     than the first 2GB (4GB) of the drive.     In the last case, you can use the remaining capacity of the disk to     give Linux a test drive.  8.4.  My 4GB+ drive has problems in MSDOS 6.22 or below.  Some BIOSes assign a drive of over 8192 cylinders a translated  geometry with 256 heads. MSDOS 6.22 and below fail when they try to  access the last head.  If your BIOS allows a user definable drive type, use a geometry with  15 heads and 16/15 times the original number of cylinders, rounded  down. Thanks to universal translation you can always do this. Remember  to write down the geometry somewhere so that you can reproduce it if  necessary! If no user definable drive type is possible, there's little  you can do about this except upgrade to Win95.!!  8.5.  Help! I have OnTrack Disk Manager installed and now...  OnTrack has a web site:  <http://www.ontrack.com/>. Most importantly,  you can find their Disk Manager FAQ at  <http://www.ontrack.com/ontrack/faqhome.html>. There's also a bit  about DM in section 13.1. If all of that doesn't help, contact OnTrack  tech support attech@ontrack.com.  Beware that some licensed versions are supported by the OEM rather  than by OnTrack. In such cases the OEM usually offers help, FAQs etc.  on their web site.  8.6.  My mode 3-4-5-6 drive has data corruption problems.  Try using a slower mode or disable fast modes altogether. Mode 3 and  especially mode 4 are very sensitive to timing problems, and not all  adapters follow the ATA-2 specification really closely. Don't dismiss  the possibility too easily: if you changed anything on your system, it  is very well possible that a drive which marginally worked so far now  starts to corrupt data.  Some controllers seem to configure themselves according to the  capabilities of the master drive. This can mean trouble if the slave  handles only slower modes.  Moreover, check your cables, and ensure they aren't too long (see  Q5.4). Removable drive brackets may also cause problems with fast PIO  modes for roughly the same reasons.  8.7.  Are there supposed to be bad sectors on the drive?  No. All modern drives support error management, which completely hides  any bad sectors that may be on the disk before leaving the factory.  Even a single bad sector is sufficient grounds to return the drive  under warranty. If you want to continue using it, the drive should be  viewed with the utmost suspicion.  Western Digital's wdat_ide.exe utility can hide grown bad sectors on  many Caviar disks.  There is one exception. Under rare circumstances, use of bad (too  fast) timing by the disk adapter can cause bad sectors on a disk. This  type of error can be fixed simply by writing fresh data to these  sectors, as there is no actual media defect.  8.8.  I keep getting CRC errors and serial overruns.  Often, this is caused by the use of block mode (see Q10.6 for an  explanation). Large blocks can take a long time to transfer; during  the transfer, interrupts are disabled and the serial ports are not  serviced by the CPU. Eventually, the buffer for incoming data may  overflow, leading to overruns and CRC errors.  The solution is to reduce the number of sectors per block, if  possible, or disabling block mode altogether. 16550 compatible serial  ports have a larger buffer, but with excessively large block sizes  this problem may still occur.  8.9.  Can my drive do 32-bit access?  There appears to be an awful lot of confusion about this subject,  partly due to some unhappy terminology.  In the most literal sense, no ATA(-2,-PI) drive will allow 32-bit  access.  Data is transferred to and from the drive over a 16 bit bus.  However, many local bus interfaces are capable of combining two 16-bit  words into a 32-bit doubleword when reading data from the disk, and  the reverse when writing. This way, data transfer between the CPU and  the interface can be done in 32-bit chunks. This is often called  '32-bit access', although '32-bit host bus transfers' would be a  better name.  With 32-bit host bus transfers, more efficient use is made of the  computer's bus and CPU. On the other hand, these are seldom the  bottleneck, so don't expect miracles from this feature. Windows'  32-bit disk and file access are completely unrelated issues and the  subject of question 8.10 and 8.11.  8.10.  Help! Windows 3.x 32-bit disk access doesn't work anymore!  There are numerous reasons why this can fail; you will more easily be  able to do something about it (or decide if you want to fix it in the  first place) once you know some background.  Windows' 32-bit disk access (32BDA) is a bit of a misnomer, actually,  since it has nothing to do with 32-bit data transfers. A slightly  better name for it is 'FastDisk'. It is a feature of Windows in 386  Enhanced mode that allows one to replace the BIOS' disk routines by  Windows' own routines that work in protected mode. A much better name,  then, would be "protected mode controller access".  For some reason  Microsoft decided not to use the latter.  Anyway, the main advantage of this feature is that it allows Windows  to use virtual memory for its DOS sessions. Without 32-bit disk  access, DOS sessions cannot be swapped out and every DOS box takes  640k of real memory. Because it also reduces the number of switches  between virtual and protected mode Windows has to make, it gives a  slight performance improvement as well, but usually nothing dramatic.  Only if 32BDA is used together with Windows for Workgroups' 32-bit  file access feature, it will eliminate these mode switches altogether  (at least for most disk operations), which gives a far more  interesting performance boost.  Unfortunately, the standard FastDisk routines that are internal to  windows, called *wdctrl, are severely limited in their capabilities.  The *wdctrl software understands nothing of non-IDE hardware (e.g.  SCSI), more than two harddrives, drives with more than 1024 cylinders,  32-bit host bus transfers, block transfers, or ATAPI CD-ROM drives on  the primary channel. If you use any of these things, 32-bit disk  access won't work unless you have a *wdctrl replacement.  Today, that means that 32-bit disk access won't work 'out of the box'  for most of us.  Most interfaces that are incompatible with *wdctrl come with their own  FastDisk routines (usually with a .386 extension). For the rest of  you, many drive manufacturers offer replacement FastDisk software.  Many drive manufacturers have such drivers on their WWW sites these  days; take a look in the net.resource guide below. You can also  contact your vendor to find out what is available. Last but not least,  the ontrackw.386 driver in  <ftp://ftp.ontrack.com/pub/software/> is reported to work  fine on all drives even if you don't use Disk Manager.  Most of these drivers won't give you 32-bit disk access if you have an  ATAPI CD-ROM on the same cable as the harddisk. Only a few CD-ROMs  come with a special VxD driver which does the job.  Note: these drivers are incompatible with the Stealth feature of some  versions of Quarterdeck's QEMM.  Quarterdeck's fix can be found on  <ftp://ftp.wdc.com/drivers/hdutil/>.  8.11.  Help! Windows for Workgroups' 32-bit file access fails!  The idiosyncrasies of the 32-bit disk access feature with respect to  disk hardware has led to the popular myth that 32-bit file access has  similar problems. However, that's all it is: a myth. If 32-bit file  access fails, you should first check your filesystem and the programs  that use it. As little as a single open file, e.g. from a printer  spooler, will cause 32BFA to fail. Oh, and put  DEVICE=C:\WINDOWS\IFSHLP.SYS in your CONFIG.SYS, and make sure your  SYSTEM.INI contains the correct magic incantations (vfat.386,  vcache.386). If this doesn't help, there's a first rate FAQ on this  topic (see the net.resource guide for details).  8.12.  Help! Win95 indicates my drive uses compatibility mode!  The culprit usually is a virus. Do get a recent virus scanner.  If that turns out negative, it may also be DOS (real-mode) driver that  loads in the CONFIG.SYS or AUTOEXEC.BAT, or an old version of  EZDrive/Disk Manager loading from the MBR.  8.13.  My partitions become a mess in MS-DOS mode.  See the next question.  8.14.  Win95 sees my partitions, but DOS doesn't.  If you've used Win95's fdisk utility to partition your drive, you may  run across a nasty bug.  Win95 supports extended int13 calls to break the 8GB barrier. To avoid  problems with old versions of DOS, partitions extending beyond 8GB  must be made invisible. Unfortunately, the Win95 FDISK sometimes hides  partitions this way even if your drive is much smaller than 8GB.  Incidentally, this also hides them from all other operating systems,  including old versions of DOS, and can cause all kinds of problems.  Under circumstances, these new partition types can completely mess up  things when going from the Win95 graphical shell to MS-DOS mode. Drive  contents may appear to be corrupted or be replaced by the contents of  C:. Don't try anything fancy when this happens; it is really easy to  corrupt your data. Don't use the "Restart in MS-DOS mode" option and  don't run programs configured to run in MS-DOS mode. MS-DOS windows  are still fine.  The most comfortable way to fix this is to change the partition types  using Partition Magic <http://www.powerquest.com>, but ONLY version  2.03 or later. You can get an update patch for older versions.  The alternative is to back up your data and repartition using FDISK  /X, which disables the use of the new partition types, or DOS 6 FDISK.  Also be sure to apply the Win95 ios bugfix and other fixes available  from Microsoft's web site.  8.15.  Win95 keeps losing my second IDE channel!  If you have a Triton II or Natoma based board, the retail version of  Win95 may not recognize the PIIX3 interface. This will trigger an  entertaining bit of Plug'n'Pray magic which eventually causes the BIOS  to disable the secondary IDE channel on the next reboot.  To determine if this is really your problem, go into the device  manager and click on Hard Disk Controllers. If you see the following  devices listed:  o  Primary IDE Controller (single FIFO)  o  Standard Dual PCI IDE Controller  o  Standard IDEESDI Hard Disk Controller/     your Win95 mshdc.inf needs a little update. You can download this     from <ftp://ftp.intel.com/pub/patch/>.  8.16.  The Win95 busmastering drivers won't work.  The Win95 busmastering drivers sometimes have trouble co-operating  with older harddisks and ATAPI CD-ROMs. Try installing the latest  drivers.  If that doesn't help, you could try this registry hack. Move all old  devices to the secondary port. Back up the registry (system.dat and  user.dat in the Win95 directory). Start regedit and look for  HKEY_LOCAL_MACHINE/System/CurrentControlSet/control/Services/hdc  Here is where the entries for both ports should be located. In the  second entry, change the key PortDriver from "ideatapi.mpd" to  "esdi_506.pdr". This will cause the secondary channel to be handled by  the default driver.  8.17.  My ATAPI (IDE) CD-ROM driver won't recognize the CD-ROM.  If the CD-ROM is connected to the secondary channel, make sure this  channel is enabled. Some BIOSes will enable the channel only if one or  more harddisks using this channel are defined in the setup; in that  case, you can't avoid putting the CD on the same cable as a harddisk  until you manage to get your BIOS updated.  You may also get trouble if the CD-ROM is jumpered as slave and  there's no master on its channel.  Finally, the PIO mode (speed) used by the interface may be too high,  especially if the CD-ROM shares its cable with a harddisk. Many  interface drivers and BIOSes are not ATAPI-aware and don't take the  CD-ROM into account when determining the maximum possible speed. The  best fix is to move the CD-ROM to a different channel. Manually  lowering the mode a notch or two should also help; this is usually  done either through the BIOS setup or by passing options to a device  driver in the CONFIG.SYS.  9.  The user's net.resource guide  There are a large number of FAQs and other resources on the net.  Daniel Tauritz (dtauritz@WI.LeidenUniv.NL) no longer maintains his  EIDE Mini-FAQ that contains a short but potentially useful list of  available interfaces; it needs to be expanded and maintained---any  takers?  There is another, technically oriented, FAQ on ATA-2, EIDE! etcetera by Hale Landis (hlandis@ibm.net).  All of this and more can! be found on  o  <ftp://ftp.wi.leidenuniv.nl/pub/faqs>  o  <http://www.wi.leidenuniv.nl/ata>  An incredible range of hardware related issues is addressed by thecomp.sys.ibm.pc.hardware FAQ, maintained by Ralph Valentino  (ralf@wpi.wpi.edu). It can be found oncomp.answers and the FAQ  repository  <ftp://rtfm.mit.edu>.  It incorporates the world-famous  'Jumper FAQ' <ftp://rtfm.mit.edu/pub/usenet/news.answers/  faq/part3>.  On the tangential subject of Windows for Workgroups' 32-bit file  access, Mike McCormick (m.mccormick2@genie.geis.com) has a good FAQ,  posted on comp.os.ms-windows.windows.setup and many other groups. It  can also be found oncomp.answers and therefore on rtfm.mit.edu as  well.  Roedy Green's (roedy@bix.com) "PCI EIDE controller flaws" FAQ is  included with his EIDE test  <ftp://garbo.uwasa.fi/pc/diskutil/> program. The latter  will test your system for the bugs that may arise if it has a CMD640  or RZ1000 interface chip (used on many pre-Triton Intel Pentium  boards, for instance). With either of these, your data is in danger  every day you postpone reading this.  The SimTel repository, the primary mirror of which is  <ftp://ftp.coast.net/> or  <http://www.coast.net>, contains an  immense number of useful programs (PD, freeware and shareware). A tiny  selection, all from /SimTel/msdos/diskutil/:  o  ideinf10.zip (will determine the properties of your     harddisk(s)--not a benchmark).  o  3drvs260.zip (gives support for 3 harddisks under DOS).  o  dqwik211.zip (block mode driver).  o  no_idle.zip (disables the auto-idle power saving feature of some     harddrives).  o  1seagate.zip (specs for *all* Seagate harddrives).  o  wasted15.zip (shows wasted space due to cluster size).  o  presz111.zip (nondestructive partition resizer).  r     Note that the version numbers may have changed; also, you should     preferably use a mirror close to you instead of the oakland site.  A more manageable selection of useful utilities, drivers and  information (this FAQ :-) can be found on  o  <ftp://ftp.netcom.com/pub/cl/clau/>     (this represents the latest known location of Chung Y. Lau's famous     wandering FTP site)  o  <ftp://ftp.rahul.net/pub/lps/>     One of the most thorough low level harddisk benchmarks on Earth,     Marnix Timmermans' Check Harddisk, is in beta. Check it out at     <http://huizen.dds.nl/~checkhd>. Of course, the usual precautions     with beta software apply.  SimTel has a copy of TheRef[TM] by F. Robert Falbo, a giant hardware  reference; it is rather outdated, but fortunately you can access a  more up to date copy on the web at  <http://theref.c3d.rl.af.mil>.  Frank Pikelner (frank@cs.yorku.ca) has compiled an excellent, up to  date list of >500MB harddisk and >4x CD-ROM drive specifications. You  can access it through  <http://www.cs.yorku.ca/People/frank/Welcome.html>.  9.1.  The user's net.resource guide: I/O card drivers! DriversHQ  <http://www.drivershq.com> is one of the most well known! sources for drivers.!  In Finland, someone got the immensely useful idea of setting up a site  with all kinds of IDE card drivers. You can find it on  <ftp://ftp.funet.fi/pub/drivers/pc/disk/ide_ata>. If you can't find a  driver here and manage to pick it up somewhere else, please upload it.  Help making the net work.  9.2.  The user's net.resource guide: hardware manufacturers  A number of disk and controller manufacturers now have FTP and web  sites; these are  o  CMD     <http://www.cmd.com>  o  Conner     <http://www.conner.com>  o  Creative Labs     <http://www.creaf.com>     Among other, non EIDE related items, this site has drivers for the     tertiary ATA/IDE port found on some SoundBlaster cards.  o  DTC     <http://www.datatechnology.com>  o  Fujitsu     <http://www.fujitsu.com>  o  Hewlett-Packard     <http://www.hp.com>  o  IBM     <http://www.storage.ibm.com/storage>     <ftp://hddtech.millcomm.com>     <http://www.pc.ibm.com> (PC Company)  o  Iomega     <http://www.iomega.com>  o  Maxtor     <http://www.maxtor.com>     <ftp://ftp.maxtor.com>     All files from their BBS are on the FTP site, including     biosbnch.zip, a benchmarking utility; greendrv.zip, to set the     sleep mode timer on 'green' drives; and the latest version of     MaxBlast (OnTrack Disk Mananager) at     <http://www.maxtor.com/readme/dm.html>.  o  Promise     <http://www.promise.com>     <ftp://ftp.promise.com>support@promise.com     This site doesn't only contain drivers for Promise products but     also for clone cards such as the VG4.  o  Quantum     <http://www.quantum.com>     No official FTP site, although drivers to use Quantum's large     harddisks with a non-translating BIOS can be found in     <ftp://ftp.rahul.net/pub/lps/hard-disk/>. This is NOT an     official Quantum support site and may disappear. This site contains     miscellaneous storage-related programs and information too, not     least the white papers on topics such as S.M.A.R.T., PRML channels,     MR heads and more:  <http://www.quantum.com/products/whitepapers/>.  o  Seagate     <ftp://ftp.seagate.com>     <http://www.seagate.com>     This includes specifications of ALL Seagate drives, including     detailed diagrams/pictures. The Seagate 32-bit disk access driver     is available as <ftp://ftp/seagate.com/techsuppt/sea32bit.exe>;     there is a FAQ on this driver at     <http://www.seagate.com/techsuppt/win32drv.html>.  There is some     general technical information available, on topics such as MR     heads:  <http://www.seagate.com/new/sep96/mr_techp.shtml>.  A     formatting utility for Seagate drives, sgatfmt4, is also available.  o  Tekram     <http://www.tekram.com>  o  Tyan     <http://www.tyan.com>  o  Western Digital     <ftp://ftp.wdc.com>     <http://www.wdc.com>     Many drivers and utilities, some of which won't work if you don't     have at least one WD Caviar drive in your system. Goodies to be     found: a good Windows FastDisk driver in /drivers/hdutil/win31.exe;     a Windows helpfile explaining Enhanced IDE in /docs/eide.exe; a     utility to examine the Enhanced DPT of your BIOS:     /drivers/hdutil/chkbios.com.  o  Winbond     <http://ntwww.winbond.com.tw>     Drivers are in the /DNLOAD/ directory.     Pointers to sites offering software from other manufacturers would     be appreciated.  9.3.  The user's net.resource guide: software and BIOS houses  o  AMI     <http://www.megatrends.com>     <ftp://ftp.megatrends.com>  o  Award     <http://www.award.com>  o  IBM     <http://www.ibm.com>     <http://www.pc.ibm.com> (PC Company)     <http://ps.boulder.ibm.com> (a really good link for OS/2 install     and update info)     <ftp://ftp.pc.ibm.com>     Flash BIOS upgrades for the IBM ValuePoints are in /pub/valuepnt/.  o  MicroHouse     <http://www.microhouse.com>     Drive specifications and jumper settings:     <http://www.microhouse.com/mtl/vip/hd.htm>. EZDrive FAQs and files     can be found on FAQ/ALLKEY.htm and FTP/EZ.htm respectively.  o  Microsoft     <ftp://ftp.microsoft.com>     <http://www.microsoft.com>     General Windows and DOS updates, fixes and Microsoft Knowledge Base     articles can be found on the Microsoft FTP site.  Unfortunately,     the structure of this site can hardly be called intuitive (which,     some would argue, is characteristic of Microsoft products in     general). The WWW site allows searches in the Knowledge Base, which     is much more useful.  o  MR BIOS     <http://www.mrbios.com>mrbios@mrbios.com     Information on MR BIOS bioses. Contains downloadable shareware BIOS     images for some popular boards with Flash ROM as well.  o  Novell     <http://www.novell.com>     <http://www.netware.com> (Netware info)  o  OnTrack     <http://www.ontrack.com>     tech@ontrack.com (tech support)sales@ontrack.com (sales)  o  Phoenix     <http://www.ptltd.com>  o  SCO     <http://www.sco.com>  o  Unicore software     <http://www.unicore.com>     Calls itself a BIOS solutions site. Contains, among other things,     information about the LBA Pro BIOS add on board.