
S P - 4 2 0 0             P I R A N H A    WESTERN DIGITAL
NO MORE PRODUCED                                      Native|  Translation
                                                      ------+-----+-----+-----
Form                 3.5"/HH               Cylinders    1280|     |     |
Capacity form/unform   209/      MB        Heads           8|     |     |
Seek time   / track  14.4/ 5.0 ms          Sector/track   40|     |     |
Controller           SCSI2 SINGLE-ENDED    Precompensation
Cache/Buffer            64 KB SEGMENTED    Landing Zone
Data transfer rate    1.500 MB/S int       Bytes/Sector      512
                      5.000 MB/S ext SYNC
Recording method     RLL 2/7                        operating  | non-operating
                                                  -------------+--------------
Supply voltage     5/12 V       Temperature *C         5 50    |    -40 60
Power: sleep              W     Humidity     %         8 80    |      5 95
       standby            W     Altitude    km    -0.305  3.048| -0.305 12.192
       idle           5.0 W     Shock        g        10       |     50
       seek           8.5 W     Rotation   RPM      3610
       read/write     6.2 W     Acoustic   dBA        40
       spin-up            W     ECC        Bit   56
                                MTBF         h      87000
                                Warranty Month        12
Lift/Lock/Park     YES          Certificates     CSA,FCC,IEC950,UL1950,VDE


**********************************************************************
                        L   A   Y   O   U   T
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WESTERN  WDSP4200/WDSP4200F  INSTALLATION GUIDE S0834 79-000543-000

  +---------------------------------------------------------+
  |+-+                                                      |XX Power
  ||x|                                                      |XX
  ||x|W3                                                    |
  ||x|                                                      |XX1
  |1-+                                                      |XX
 ++  LED           REVISION 1                               |XX I
 ++                                                         |XX N
  |+-+                                                      |XX T
  ||x|W1                                                    |XX E
  ||x|                                                      |XX R
  |1-+                                                      |XX F
  |                                                         |XX A
  |                                                         |XX C
  |                                                         |XX E
  |                                                         |XX
  |                                                         |XX
  |                                                         |XX
  +---------------------------------------------------------+







  +---------------------------------------------------------+
  |+-+                                                      |XX Power
  ||x|W3                                                    |XX
  ||x|                                                      |
  |1-+                                                      |XX1
  |+-+J4                                                    |XX
  |+-+             REVISION 2                               |XX I
 ++LED                                                      |XX N
 +++--+J5                                                   |XX T
  |+--+                                                     |XX E
  |+-+                                                      |XX R
  ||x|W1                                                    |XX F
  ||x|                                                      |XX A
  |1-+                                                      |XX C
  |                                                         |XX E
  |                                                         |XX
  |                                                         |XX
  |                                                         |XX
  +---------------------------------------------------------+



**********************************************************************
                      J   U   M   P   E   R   S
**********************************************************************
WESTERN  WDSP4200/WDSP4200F  INSTALLATION GUIDE S0834 79-000543-000

 Jumper Setting
 ==============

 x = Factory default setting


 Revision 1
 ----------

 Termination
     |       Reserved                     Spin-up
     |      LED |   SCSI ID          Reserved|  +-ANSI/APPLE SCSI
     +-+-+   |  |  +--+--+                |  |  |  +Parity
      13 11  9  7  5  3  1     LED        7  5  3  1
  ---+--+--+--+--+--+--+--+---+---+-----+--+--+--+--+---+   +----
     |XX|XX|XX|XX|XX|XX|XX|   | O |     |XX|XX|XX|XX|   |   |
 ----+--+--+--+--+--+--+--+---+---+-----+--+--+--+--+---+---+------
      14 12 10  8  6  4  2                8  6  4  2
      +--------+---------+               +----+----+
               W3                            W1



 Revision 2
 ----------

 Termination             Connector for
      |                  Optional Fuse
      |Reserved                |    Reserved
      |   |   SCSI ID LED      | LED  | Spin-up
      |   |  +--+--+   |       |   |  |  |  +----ANSI/APPLE SCSI
       9  7  5  3  1  J4  LED  J5  9  7  5  3 +1--Parity
  ---+--+--+--+--+--+----+---+---+--+--+--+--+--+---+   +----
     |XX|XX|XX|XX|XX| xx | O | X |XX|XX|XX|XX|XX|   |   |
 ----+--+--+--+--+--+----+---+---+--+--+--+--+--+---+---+------
      10  8  6  4  2              10  8  6  4  2
      +------+-----+               +-----+-----+
             W3                          W1


 The Piranha SP4200 and SP4200F drives have two jumper blocks, W1 and
 W3, located on either side of the internal LED. Some Piranha
 revisions have a third jumper, J4, and a fuse socket, J5.

 If the drive is supplied with the faceplate installed, you must re-
 move it to access the jumpers.


 W3 SCSI Device ID
 -----------------
   +----------+-----------------------+
   | SCSI ID  |        Jumpers        |
   |          | 5-6   | 3-4   | 1-2   |
   +----------+-------+-------+-------+
   |x   0     | OPEN  | OPEN  | OPEN  |
   +----------+-------+-------+-------+
   |    1     | OPEN  | OPEN  | CLOSED|
   +----------+-------+-------+-------+
   |    2     | OPEN  | CLOSED| OPEN  |
   +----------+-------+-------+-------+
   |    3     | OPEN  | CLOSED| CLOSED|
   +----------+-------+-------+-------+
   |    4     | CLOSED| OPEN  | OPEN  |
   +----------+-------+-------+-------+
   |    5     | CLOSED| OPEN  | CLOSED|
   +----------+-------+-------+-------+
   |    6     | CLOSED| CLOSED| OPEN  |
   +----------+-------+-------+-------+
   |    7     | CLOSED| CLOSED| CLOSED|
   +----------+-------+-------+-------+

 Each device on the SCSI bus must have a unique device identifying
 number in the range 0 to 7. W3 jumper pins 1 through 6 are used to
 set the device ID.


 Externally Activity LED
 -----------------------
 If your system configuration allows the use of an activity LED
 external to the Piranha drive, you can power the LED from the drive.

 Activity LED options if J4 is NOT present:

 - W3 jumper pins 9-10 provide power for an external activity LED.

 Activity LED options if J4 IS present:

 - W1 jumper pins 9-10 provide power for an external activity LED.
   Jumper J4 also provides external LED power via a 2-pin 2-mm
   connector.

 If you using the WD 5.25 Kit, refer to the LED installation
 instructions in the kit. To install an external activity LED from the
 system, connect the positive lead (anode) of the LED to pin 10 and
 the negative lead (cathode) to pin 9.


 SCSI Termination
 ----------------
 The devices at each end of the SCSI bus must be terminated. Since the
 SCSI cable is actually an extension of the bus, you must terminate
 the devices physically located at the ends of the cable. All devices
 between the ends of the cable must be unterminated. The host bus
 adapter is unterminated if it is in the middle of the cable. If the
 Piranha drive is to be at either end of the SCSI cable, the drive
 must be terminated.

 To terminate the Piranha drive, you must set a jumper, and you must
 have termination power. Termination power can come from the SCSI bus
 (directly or through a host bus adaptor) or from the drive which is
 being terminated.

 There are different jumper options for termination, depending on
 whether the bus or the drive is to supply the termination power.
 Consult your system or host adapter documentation to determine if
 your SCSI bus supplies termination power. (Most systems do supply
 termination power.) If your system does not, then you must use power
 supplied by the Piranha drive.

 The jumper options for termination are on the W3 jumper block. They
 vary depending on which version of the Piranha you have.


 Termination options if J4 is NOT present:

 - To terminate the Piranha drive with termination power coming from
   the SCSI bus, leave the jumper shunt on pins 11-12. This is the
   factory default setting. If you are not sure whether your system
   supplies termination power, try this setting first, since is the
   most common.

 - To terminate the Piranha drive with termination power coming from
   the drive, move the jumper shunt from pins 11-12 to pins 12-14.
   Note that this requires an uncommon sideways placement of the
   jumper shunt.

 - To make the drive unterminated, remove the jumper shunt from pins
   11-12. The unterminated setting is no shunts on pins 11 through 14.


 Termination options if J4 IS present:

 - To terminate the Piranha drive, leave the jumper shunt on pins
   9-10. This is the factory default setting.

 - To make the drive unterminated, remove the jumper shunt from pins
   9-10.

 - In the unusual event that power is not supplied by the host or
   another SCSI device, the Piranha can supply termination power.
   To enable termination power from the Piranha drive, you must
   procure and install a fuse in the J5 connector. Disconnect the
   power source before installing the fuse.


 Parity Checking
 ---------------
 The SCSI bus provides a parity bit to allpw parity checking of data
 on the bus. Parity checking improves data reliability. The default
 mode of the Piranha drive enables parity checking. To disable parity
 checking, install a jumper shunt on W1 jumper pins 1-2


 ANSI/Apple SCSI
 ---------------
 Apple Computer products use the SCSI bus in a slightly different
 manner than other computers. The Piranha drive supports both the
 Apple SCSI implementation and the conventional ANSI SCSI implementa-
 tion via W1 jumper pins 3 and 4. The default configuration (no jumper
 shunt), enables ANSI SCSI. Install a jumper shunt on Pins 3-4 to
 enable Apple SCSI.


 Spin-Up at Power-On
 -------------------
 The Piranha drive can be configured to automatically spin up when
 power is applied to the drive, or to spin up only on command from the
 host. Regardless of whether automatic spin up is enabled, the drive
 will always respond to the host command. A jumper shunt on W1 jumper
 pins 5-6 enables automatic spin up at power-on. This is the factory
 setting. To enable spin-up on command only, remove the jumper shunt
 from pins 5-6.



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                      I   N   S   T   A   L   L
**********************************************************************
WESTERN  WDSP4200/WDSP4200F  INSTALLATION GUIDE S0834 79-000543-000


 Notes on Installation
 =====================

 Drive mounting
 --------------

     horizontally             vertically
   +-----------------+   +--+             +--+
   |                 |   |  +-----+ +-----+  |
   |                 |   |  |     | |     |  |
 +-+-----------------+-+ |  |     | |     |  |
 +---------------------+ |  |     | |     |  |
                         |  |     | |     |  |
                         |  |     | |     |  |
                         |  +-----+ +-----+  |
                         +--+             +--+


 Before Installing the Drive
 ---------------------------
 Be sure that you have the following items before installing your new
 drive:

 - Computer system manual

 - Operating system manual

 - Host bus adapter and information, if applicable

 - 50-pin interface cable, maximum 6 meters long

 There are some other items you may require:

 - You may need jumper shunts, available from your dealer, if you
   change the drive configuration.

 - You may need a power Y-adapter if you are installing the drive as a
   second hard drive and you not have two internal power connectors.

 - You may need a fuse if termination power is not supplied by the
   host or another SCSI device.

 - Some systems require drive mouning rails. Check your computer
   system manual to determine if mounting rails are required. These
   rails can be purchased through your computer manufacturer or
   dealer.

 - If you are installing the Piranha intelligent drive in a 5-1/4"
   drive bay, you need a 5-1/4" frame. This frame mounts on the drive
   and adapts it to the larger bay. Western Digital offers a 5.25
   Kit, which may be purchased from your dealer.

 The WD 5.25 Kit contains one 5-1/4" frame, two faceplates with LEDs,
 and screws for connecting the drive frame and faceplate to the
 Piranha drive.


 Mounting Restrictions
 ---------------------
 The Piranha drive may be mounted with the top, bottom, left, or
 right side down, depending on the physical design of your system. The
 Piranha is mounted with four 6-32 screws.

 Screws which are too long will damaga the board components. Mounting
 screws must engage no more than six threads (3/16 inch).

 Caution
 You may damage the Piranha drive or the host system if the interface
 cable is not connected properly. Confirm that you are cabling the
 drive to a 50-pin connector on the system or host bus adapter. Be
 sure to match pin 1 on the cable to pin 1 on the connector. To
 prevent incorrect correction, use a cable that has keyed connectors.


 Cabling
 -------
 The Piranha SP4200 and SP4200F drives require a 50-pin cable not
 longer than six meters. If multiple devices are attached to the SCSI
 bus, the devices must be daisy-chained, using a cable with multiple
 connectors. The ends of the cable must be connected to terminated
 devices. If the cable contains more connectors than needed for the
 devices on the bus, mid-cable connectors remain unused.


 Power Connectors, Cables, and Fuse
 ----------------------------------
 Power Connector                4 Pin: AMP P/N 770671-1
 Mating Power Connector         Body: AMP 1-480424-0
                                Pins: AMP 60619-4
 Power Cable Wire Gauge         18 AWG
 Mating SCSI Connector          50-Pin: MOLEX P/N 70248
 Fuse                           Microfuse: 2-pin, 1 Amp, 125V, Little-
                                fuse P/N 272001
 Mating External LED Connector  Molex housing 50-57-9002. Power
                                provided is 15mA max. at +5VDC

 Equivalent parts may be used.


 Removing the Factory-Installed Faceplate
 ----------------------------------------
 The Piranha faceplate is held on the drive by a hook on the upper
 edge and two spring-fit retaining pins on the bottom that engage
 holes in the drive base assembly.

 1. Place the drive, faceplate up, on an antistatic surface.

 2. Insert a ball point pen or similar tool in the retaining holes and
    carefully press each retaining pin to disengage it from the hole.

 3. Lift the faceplate straight up to free the hook on the top surface
    of the drive.



**********************************************************************
                      F   E   A   T   U   R   E  S
**********************************************************************
WESTERN  WDSP4200/WDSP4200F  INSTALLATION GUIDE S0834 79-000543-000


 Overview
 --------
 The Western Digital Piranha SP4200 and SP4200F are 209.7 megabyte
 disk drives suitable for use a new, upgrade, or replacement drives in
 systems utilizing the Small Computer System Interface (SCSI), includ-
 ing AT systems with SCSI Host Bus Adapters.

 The SP4200 and SP4200F are distinguished by the synchronous data
 transfer rate of the SCSI-2 interface:

 - The SP4200 has a maximum transfer rate of 5.0 megabytes per second.

 - The SP4200F has a maximum transfer rate of 10.0 megabytes per
   second.

 Piranha also offers an average seek time of less than 15 milli-
 seconds, and a 12.66 megabit-per-second media transfer rate.

 Because of its compact, half-height size, the Piranha drive is easily
 incorporated into the newest generation systems. It has been designed
 for applications that demand a ombination of advanced processing
 power and high performance, including highspeed desktop PCs, CAD/CAM,
 engineering workstations, network file servers, and desktop publish-
 ing. The Piranha ua a 3-1/2" drive that can also be used in a 5-1/4"
 drive bay with a drive frame available from your dealer.

 The Piranha drive is preformatted (low-level) and defect-free.


 The Piranha drive offers the following features:

 - Active SCSI termination, a patended Western Digital feature,
   incorporates unique termination electronics which allow termination
   of the drive via a single jumper. This significantly eases
   installation.

 - Automatic head parking retracts the heads, on power down, to a
   safe, non-data landing zone and locks them into position.

 - Piranha supports a comprehensive SCSI-2 command set, which allows
   5 megabytes-per-second (SP4200) or 10 megabyte-per-second (SP4200F)
   Fast SCSI data transfers.

 - Piranha includes CacheFlow, the industry's first adaptive, multi-
   segmented disk caching system.

 CacheFlow constantly evaluates both the size and type of the data
 request, dynamically partitons the 64-Kbyte buffer into caching seg-
 ments, and automatically selects the appropriate caching mode for
 optimum performance.


 Seek Time
 ---------
       +----------------------------------+--------+
       |Track-to-Track         msec. typ. |   5    |
       +----------------------------------+--------+
       |Average                msec. typ. |  14.4  |
       |                       msec. max. |  26    |
       +----------------------------------+--------+
       |Latency                msec. avg. |   8.31 |
       +----------------------------------+--------+



**********************************************************************
                      G   E   N   E   R   A   L
**********************************************************************
WESTERN   TIPS

 WESTERN DIGITAL 3.5-INCH DRIVES FREQUENTLY ASKED QUESTIONS
 ----------------------------------------------------------
 1) Will a Caviar drive work in my system?
   If your computer is 100% AT compatible and has either a 40-pin AT
   IDE interface on the motherboard or an IDE controller card with a
   40-pin data cable.

 2) What are the master/slave jumper settings on Western Digital
    drives?
    All Western Digital drives are configured the same. On the back of
    the drive between the 4-pin power connector and the 40-pin data
    connector, there is a jumper block J8 consisting of 6 pins.
    Western Digital hard drives are shipped with a jumper shunt in the
    neutral storage position (across pins 5 and 3) for future dual
    drive use.

 - If you are installing the Western Digital hard drive as the only
   hard drive in your system, leave the jmper shunt in the neutral
   storage posiition. Jumper shunts are not required for single hard
   drive installations.

 - To designate the Western Digital hard drive as the master (C:),
   place a jumper shunt on pins 5-6

 - To designate the Western Digital hard drive as the slave (D:),
   place a jumper shunt on pins 3-4.

 3) What are the drive type and the drive parameters in the CMOS, for
    Western Digital drives?
    On top of the drive, the number of cylinders, heads and sectors
    per track are printed on the label. Precomp and L-zone should be
    set equal to the drive's cylinder count + 1. Select user type or
    custom type (typically type 41 or 42) for your drive. This will
    allow you to type in the parameters. Older systems that do not
    offer a user type can either upgrade the system BIOS or set the
    drive to drive type 1 (which should be a smaller drive size), and
    run Ontrack Disk Manager from A drive to get the full capacity of
    the drive. If you do not follow one of these procedures and your
    system is pre-1994, you will be limited to the largest size drive
    your BIOS will allow.

 4) What is the Ontrack Disk Manager software that came with my drive
    and what does it do?
    Ontrack Disk Manager is the original hard disk installation
    package that will initialize, partition, and prepare your hard
    drive for use. Ontrack Disk Manager also allows you to access the
    full capacity of the drive even when your system BIOS can't. It is
    compatible with 32-bit disk access.

 Note: Ontrack Disk Manager must be installed from floppy drive A. If
 your A drive is a 5.25-inch floppy drive, copy the contents of your
 Ontrack Disk Manager disk to a formatted 5.25-inch disk and re-run
 Ontrack Disk Manager.

 5) I just installed Ontrack Disk Manager on my Caviar drive and tried
    to install DOS. DOS attempted to write to my drive and it
    formatted my drive back to 528 MB which is my BIOS limitation. How
    do I install DOS and still get the full capacity of my drive?
    After Ontrack Disk Manager installation, you must create an
    Ontrack Disk Manager rescue disk. There are two ways of
    accomplishing this:

 OPTION 1:
 - Create a clean DOS bootable disk.

 - Copy 2 files from the Ontrack Disk Manager disk to your bootable
   disk: XBIOS.OVL, and DMDRVR.BINs Create a CONFIG.SYS file on this
   bootable disk with these 3 lines: DEVICE=DMDRVR.BIN FILES=35
   BUFFERS=35

 - Remove the floppy and reboot the system.

 - When you see the message "Press spacebar to boot from diskette",
   press the spacebar (system halts).

 - Insert the rescue disk in the A: drive.

 - Press any key (system resumes boot process).

 - At the A: prompt, remove rescue disk, insert DOS installation disk
   and type SETUP.

 - You can now install DOS without overwriting the Ontrack Disk
   Manager files.

 OPTION 2:

 - Create a clean DOS bootable disk.

 - Insert Ontrack Disk Manager disk in the A: drive.

 - At the A prompt, type: DMCFIG/D=A:. You will be prompted to insert
   a bootable floppy in the A: drive.

 - Follow the prompts on the screen. Ontrack Disk Manager will ask you
   to change disks a few times.

 - Continue until Ontrack Disk Manager is finished.

 - Remove the floppy and reboot the system.

 - When you see the message "Press spacebar to boot from diskette".
   Press the spacebar (system halts).

 - Insert the rescue disk in A drive.

 - Press any key (system resumes boot process).

 - At A prompt, remove rescue disk, insert DOS installation disk and
   type SETUP.

 - You can now install DOS without overwriting the Ontrack Disk
   Manager files.

 6) CHKDSK or SCANDISK reports a few bad sectors. How do I go about
    fixing the problem.
    You can use the Western Digital defect management utility WDATIDE.
    One of its options is the comprehensive surface analysis. This
    procedure will mark all grown defects bad if indeed there are any
    and it will compensate for the lost capacity by utilizing spare
    tracks.

 Note: This utility is data destructive. Back up all data on the drive
 before using it. Due to the thoroughness of this operation, WDATIDE
 can take quite a bit a time depending on the capacity of your drive.

 7) Do I have to do anything with my original drive when adding a new
    drive to my system?
    Yes, one hard drive must be designated as the master drive
    (preferably the newer, faster drive) and the other must be
    designated as the slave drive. Typically, most drives need to have
    a jumper placed on them to specify the Master or Slave position.
    For information on non-Caviar hard drives, please contact the
    appropriate manufacturer.

 8) I installed my new drive and entered the drive parameters in the
    CMOS, but the drive will not boot or it displays the message "HDD
    controller failure."
    Your drive must be partitioned and formatted before it will be
    bootable. If your system will support drives larger than 528 MB,
    and you have a copy of MS-DOS or PC-DOS version 5.0 or greater,
    insert the setup diskette in your floppy drive and turn on your
    computer. Follow the prompts and DOS will partition and format the
    drive for you.

 If you do not have a copy of MS-DOS or PC-DOS version 5.0 or greater,
 you will need to boot from a bootable disk and then run the FDISK
 command to partition your drive, and then format the drive using the
 DOS FORMAT command. After running format, you should be able to
 reboot your computer from your hard drive.

 9) How can I use the full capacity of my Caviar drive of 540 MB or
    greater?
    You can use Ontrack Disk Manager to obtain full capacity if your
    system does not support LBA mode. If your system does support LBA
    mode, you can enable LBA in your CMOS setup utility.

 10) How can I get 32-Bit Disk Access in Windows on my Caviar AC2540,
     AC2700 or AC31000 in Windows 3.1x? If your BIOS supports the
     drive at full capacity (i.e., the BIOS supports Logical Block
     Addressing) you use WDCDRV.386, Western Digital's FastDisk device
     driver. This driver is contained in a file named WIN31.EXE
     available for downloading from our bulletin board (714/753-1234),
     our Web server (WWW.WDC.COM), our FTP site (FTP.WDC.COM), our
     forum on the Microsoft Network (Go word WDC), and our forum on
     America On-line (keyword WDC). If your BIOS does not support LBA
     mode and you have installed your drive using Ontrack Disk Manager
     (v6.03 and above), run DMCFIG to install WDCDRV.386 and obtain
     32-Bit Disk Access.

 11) My drive will not spin up or spins down after a few seconds.
     This is a drive failure. Return the drive to the distributor or
     contact a technical support representative to receive a Return
     Materials Authorization (RMA).

 12) CMOS, FDISK and File Manager in Windows report less than the
     capacity of my new drive, but CHKDSK reports the right number of
     bytes. Which is correct?
     Setup (CMOS) and FDISK use a binary definition of a megabyte
     which is calculated at 1,048,256 bytes per megabyte. All hard
     drive manufacturers and the DOS CHKDSK utility use a decimal
     definition of a megabyte which is calculated at 1,000,000 bytes
     per megabyte. This is why some utilities show 515 MB for a 540
     megabyte drive and some show the actual number.

 13) How Can I install OS/2 for Windows, OS/2 3.0 WARP, Windows NT
     3.5x or Windows 95 on my drive which was initially installed
     using Ontrack Disk Manager?
     If you have Ontrack Disk Manager version 6.03, 6.03a, or 6.03b,
     download the file named DMPATCH.EXE from Western Digital's online
     services: ftp site: ftp.wdc.com

 World Wide Web Site: http://www.wdc.com/
 Microsoft Network (MSN) - Go word WDC
 America Online (AOL) - Keyword: Western Digital
 Western Digital's BBS at (714) 753-1234
 This file has the latest Ontrack Disk Manager drivers which will
 allow you to install OS/2 version 2.1x, OS/2 WARP, Windows NT 3.5x
 or Windows 95 on your hard drive. Please read the included readme
 file with this file for further detail.

 14) My drive will work as a slave but not as a master (or vice-
 versa).
 Check master/slave jumpers on all drives. Also, some drive's speed
 and timing differ drastically as to the initial spinup sequence. This
 might confuse the system and cause one of the drives not to be
 recognized. The best solution for this situation is to exchange
 drives (make the master a slave and vice-versa).

 15) My drive will not partition when I run FDISK. It hangs the system
     or it displays the message: "Runtime error."
     This is usually caused by corruption or damage to track zero. Use
     the Western Digital utility WDFMT to format the drive. If that
     does not help, call Western Digital Technical support at
     1-800-ASK-4-WDC to get further instructions.

 16) Can a hard drive be mounted on it's side, edge, or upside down?
     Drives can be mounted on any side but it is preferable to mount
     the drive right side up. It is also important to use all four
     screws to hold the drive firmly in place.


 Self-Monitoring, Analysis, and Reporting Technology (S.M.A.R.T.)
 ----------------------------------------------------------------
 S.M.A.R.T. enables a drive's internal status to be monitored through
 diagnostic commands at the host level.

 The Caviar AC21600, AC32100 and AC32500 drives monitor read error
 rate, start/stop count, spin-up retry count, and drive calibration
 retry count. All of these attributes are updated and stored on the
 hard drive in the reserved area of the disk. The hard drive also
 stores a set of attribute thresholds that correspond to the
 calculated attribute values. Each attribute threshold indicates the
 point at which its corresponding attribute value achieves a negative
 reliability status.
 ====================================================================

  QUESTION
  Which hard drive specification is most important to overall
  system performance ?

 - Host Transfer Rate
 - Drive RPM (revolutions per minute)
 - Disk Transfer Rate (Media Rate)
 - Seek Time
 - Cache Size
 - PC Data Handling
 - All of the above

 Answer
 The correct answer is actually a combination of "all of the above,"
 keeping in mind most of the above specifications are interrelated
 when it comes to optimizing system performance.

 The pie chart illustrates the relative influence of factors affecting

 drive performance during a typical random I/O operation (reading
 and writing to a hard drive).

 The major determinate of hard drive performance is mechanical
 factors which are one hundred times slower than the high-speed
 electronics contained in a drive.


 Factors Affecting Hard Drive Performance
 (In their relative order of importance)

 MECHANICAL LATENCIES
 Mechanical Latencies include both Seek Time and Rotational
 Latency. The seek time is a measure (in milliseconds) of how
 fast the hard drive can move its read/write heads to a desired
 location. Rotational latency is a measure of the average time
 (also in milliseconds) the read/write heads must wait for the
 target sector on the disk to pass under them once the read/write
 heads are moved to the desired target track.

 Mechanical latencies are the main hindrance to higher performance
 in modern Enhanced IDE (EIDE) hard drives. The time delays of
 mechanical latencies are one hundred times higher than
 electronic (non-mechanical) latencies associated with the
 transferring of data. Therefore, reducing mechanical latencies
 (a lowering of seek time and rotational latency) should be the
 top consideration in improving hard drive performance.

 RPM
 This is the rotational speed of the media (disk), also referred
 to as the spindle speed. Hard drives only spin at one constant
 speed. Typical speeds are 3600 to 3880, 4500, and 5200 to 5400
 revolutions per minute. The slower the RPM, the higher the
 Mechanical Latencies. Disk RPM is a critical component of hard
 drive performance because it directly impacts the rotational latency
 and the Disk Transfer Rate explained below.

 DISK TRANSFER RATE
 The Disk Transfer Rate (sometimes called media rate) is the
 speed at which data is transferred to and from the disk media
 (actual disk platter) and is a function of the recording frequency.
 Typical units are bits per second (BPS), or bytes per second.
 Modern hard disks have an increasing range of Disk Transfer
 Rates from the inner diameter to the outer diameter of the disk.
 This is called a "zoned" recording technique.

 The key media recording parameters relating to density per platter
 are Tracks Per Inch (TPI) and Bits Per Inch (BPI). A track is a
 circular ring around the disk. TPI is the number of these tracks
 that can fit in a given area (inch). BPI defines how many bits
 can be written onto one inch of a track on a disk surface. To
 greatly simplify, the Disk Transfer Rate (the rate at which data
 is read and written to the disk) is dependent upon the speed of
 the disk (RPM) and the density of the data on the disk (BPI).
 Even most modern, high-speed, 5000 RPM hard drives are generally
 limited to a maximum Disk Transfer Rate of approximately 9 to 10
 MB per second. This specification is critical to performance and
 must be weighed carefully against such electronic latencies as
 Mode 3 PIO and Mode 4 PIO host transfer rates explained below.

 PC DATA HANDLING
 After the data moves down the IDE cable from the drive to the host
 interface, there are several factors that can affect drive
 performance over which the hard drive has no control. PC Data
 Handling is independent from the hard drive and very dependent
 upon the CPU type and speed, the BIOS overhead (how the system
 issues commands to the hard drive), speed and size of the system
 RAM and RAM cache, CPU-to-memory speed, and storage subsystem
 performance. PC Data Handling is also affected by the caching
 methods of such software applications as SMARTDRIVE, 32-bit
 disk access operating system drivers, etc.

 HOST TRANSFER RATE
 The speed at which the host computer can transfer data across the
 IDE or EIDE interface. Processor Input/Output (PIO) modes and
 Direct Memory Access (DMA) modes are defined in the ATA-2 industry
 specification as follows:

 Mode 3 PIO  11.1 MB/sec
 Mode 4 PIO  16.6 MB/sec
 Mode 1 DMA  13.3 MB/sec
 Mode 2 DMA  16.6 MB/sec

 Modern host computer systems usually support most of the above
 modes. Faster Host Transfer Rates in the future will use multi-word
 DMA modes as the industry will not support any future PIO mode
 standards beyond mode 4.

 The computer system manufacturer is responsible for implementing a
 Host Transfer Rate that is high enough to ensure that the host
 computer is not the performance bottleneck. Implementing
 increasingly higher Host Transfer Rates without corresponding
 increases in Disk Transfer Rates on the hard drive will not result
 in increased drive performance.


 Cache Buffer Size - Is Bigger Always Better ?
 A Cache Buffer is similar to a water glass. When you are writing
 to a hard drive, the host computer fills the glass and the disk
 media empties it. If you are reading data from a hard drive, the
 disk media fills the glass and the host computer empties it.

 The reason that a bigger cache buffer is not always better
 (or faster) is because the host computer (with Mode 4 PIO or
 Mode 2 DMA capabilities) can empty or fill the glass much faster
 than the hard drive can empty or fill it. When the host system can
 transfer data in or out of the cache buffer faster than the media
 rate, a larger buffer size becomes irrelevant because the host
 system is always "waiting" for the hard drive.

 Western Digital hard drives are designed with cache buffer sizes
 that are matched to the Disk Transfer Rate capabilities of the
 drive and the Host Transfer Rates of modern computer systems. All
 of our drives are benchmarked with various cache buffer sizes to
 verify that the most cost-effective and performance-effective
 cache size is implemented.


 Confusion Over Mode 4 and Mode 2 DMA
 The Enhanced IDE program created the long-range road map for
 performance enhancements which included faster disk and host
 transfers, Mode 3, Mode 4, Mode 2 DMA, etc. Currently, computer
 systems and hard drive controller silicon have most of the elements
 needed to implement Mode 4 PIO or Mode 2 DMA (a 16.6 MB/sec Host
 Transfer Rate). However, to take advantage of these performance
 modes, physical drive architecture must also make some performance
 improvements in the area of Mechanical Latencies and Disk Transfer
 Rate (media rate) as defined earlier.

 Some competitors, in their eagerness to supply a new feature, are
 prematurely marketing Mode 4 and Mode 2 DMA. While their drive
 controller silicon supports these modes (which is very easy and
 inexpensive to implement), spindle speeds (RPM), rotational latency,
 bit density, and other factors have not yet been improved (these
 being very difficult and costly). The result is hard drives which
 have the electronic capability to do Mode 4 and Mode 2 DMA transfer
 rates, but can't take advantage of these modes due to the slower
 Disk Transfer Rate of the drive.

 Western Digital will not be implementing Mode 4 or Mode 2 DMA on
 older drive products as the host systems into which these drives
 are designed are not electrically capable of these data transfers,
 nor are the Disk Transfer Rates on these drives beyond current Mode
 3 capabilities. As next generation systems are introduced, they will
 be paired with next generation drives. Those drives will require
 and offer true Mode 4 / Mode 2 DMA capability from a total drive
 architecture standpoint.
 =====================================================================
 AC2540/2635/2700/2850/21000/31000/31200/31600

 Windows 95 Operating System Addendum
 ------------------------------------
 The information in this addendum supersedes that supplied in Windows
 95 section on pages 35 and 36 of this manual. Please refer to thos
 addendum for Windows 95 questions.

 Although Windows 95 is capable of recognizing the full capacity of
 hard drives larger than 528 MB in systems with a translating BIOS,
 some restrictions apply to systems without a translating BIOS.


 For Systems With a Translating BIOS
 -----------------------------------
 Enter your CMOS setup and select a drive type that will recognize the
 full capacity of your drive. This is usually done by selecting the
 auto config drive tape. The boot partition can be set up to be as
 large as the full capacity of your hard drive.


 For Systems Without a Translating BIOS
 --------------------------------------
 Enter your CMOS setup and select a user defined drive type. Enter
 these parameters: cylinders = 1024, heads = 16, sectors = 63. Your
 system's total disk space will be limited to a maximum of 528MB.

 If you want your system to utilize more than 528 MB of disk space,
 you must use Ontrack's Disk Manager software (or a similar third-
 party installation software).


 Installing Windows 95 on a Hard Drive with Ontrack Disk Manager
 Already Installed
 ---------------------------------------------------------------
 The Windows 95 installation program will analyze your computer
 system and install seamlessly with Ontrack Disk Manager.


 Computer Systems with Windows 95 Already Installed
 --------------------------------------------------
 If you are installing a Western Digital hard drive and Ontrack Disk
 Manager on a computer system with Windows 95 already installed, you
 must install Ontrack Disk Manager as described here.

 Enter your CMOS setup and select a user defined drive type. Enter
 these parameters for drives with capacities over 528MB:
         Cylinders = 1024, Heads = 16, Sectors = 63.

 Save these changes and reboot your computer.

 1. Select the Start icon from the Windows 95 main screen.
    DO NOT open an MS-DOS menu from Win 95 to install Ontrack Disk
    Manager.

 2. Choose the Shut Down option.

 3. Select Resatrt Computer in DOS mode. When your computer restarts,
    you should be at the DOS prompt.

 4. Install Ontrack Disk Manager.

 Windows 95 will noe recognize the full capacity of your hard drive
 and run in 32-bit disk access mode for optimum performance.


