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Hard Drive: WESTERN DIGITAL: CU-140 (AT) 43MB 1.8"/SSL IDE / AT

C U - 1 4 0   ( A T )    WESTERN DIGITAL
NO MORE PRODUCED                                      Native|  Translation
Form                 1.8"/SUPERSLIMLINE    Cylinders    1050|  980|     |
Capacity form/unform    43/      MB        Heads           2|    5|     |
Seek time   / track  19.0/ 5.0 ms          Sector/track     |   17|     |
Controller           IDE / AT              Precompensation
Cache/Buffer            32 KB STATIC RAM   Landing Zone
Data transfer rate    2.000 MB/S int       Bytes/Sector      512
                      4.500 MB/S ext
Recording method     RLL 1/7                        operating  | non-operating
Supply voltage     5 V          Temperature *C           55    |    -40 70
Power: sleep              W     Humidity     %         8 85    |      5 95
       standby        0.1 W     Altitude    km    -0.500  3.000| -0.500 12.000
       idle           0.5 W     Shock        g       100       |    200
       seek               W     Rotation   RPM      4503
       read/write     1.7 W     Acoustic   dBA        37
       spin-up        3.0 W     ECC        Bit   ON THE FLY,REED SOLOMON
                                MTBF         h     255000
                                Warranty Month        24
Lift/Lock/Park     YES          Certificates



  |                                                       |+-+
  |                                                       ||X|I
  |                                                       ||X|N
  |                                                       ||X|T
  |                                                       ||X|E
  |                                                       ||X|R
  |                                                       ||X|F
  |                                                       ||X|A
  |                                                       ||X|C
  |                                                       ||X|E
  |                                                       ||X|
  |                                                       |+-+



Jumper Setting

Dual Installations
Dual installations require a master/slave drive configuration, where
one drive is designated as the primary (master) drive and the other
is designated as the secondary (slave) drive. The Caviar UltraLite
drive (in AT mode) is compatible in dual installations with other
intelligent drives that supports a master/slave configuration.

Cable Select (CSEL)
Caviar UltraLite supports CSEL signal on the drive cable as a drive
address selection. When enabled, the drive address is 0 (Master) if
CSEL is low, or 1 (Slave) if CSEL is high.

The SDH Register contains the master/slave select bit for the Caviar
UltraLite. The DASP signal is a time-multiplexed indicator of "drive
active or slave present" on the Caviar UltraLite's I/O interface. At
reset, this signal is an output from the slave drive, and an input to
the master drive, showing that a slave drive is present. For all
times other than reset, DASP is asserted at the beginning of command
processing and released upon completion of the command. If the master
drive option has been configured, the Caviar UltraLite will not
respond to commands or drive status on the interface when the slave
bit is selected in the SDH Register.



Notes on Installation

Mounting the Drive
The Caviar UltraLite is specifically designed for removability. Being
form factor compatible with the PCMCIA Type III specification, the
CU140 can be inserted into a Type III slot and is supported within
the slot by the drive's connector and guide rails.

Spring loaded slots provide additional support by springs pressing
against the rails and protecting the drive from unnecessary movement.

For embedded solutions, compression-type mounting with compression
applied to the rails is recommended.

The drive is normally grounded through the 68-pin host interface
connector. Additional grounding can be achieved through a spring
contact directly applied to the HDA base or cover.

Moving Precautions
The CU140 is designed to withstand the constant movement typical of
the mobile PC environment. For precautionary purposes, it is always
recommended that the user invoke the automatic head parking feature
when the computer is not in use by turning the power off. In addition
to preserving battery life, this helps protect the media and heads
from accidental damage by locking the heads in a safe, non-data
landing zone.

Mounting Restrictions
The Caviar UltraLite can be mounted in many different ways depending
upon the physical design of your system.

 DC Electrical Specifications
  |PINS: 2-6, 30-32, 37-41, 64-66                                   |
  |Voh    | Output High Voltage| 2.4|    |  V   | Iout = -3mA       |
  |Vol    | Output Low Voltage |    | 0.4|  V   | Iout = 24mA       |
  |Vih    | Input High Voltage | 2.0|    |  V   |                   |
  |Vil    | Input Low Voltage  |    | 0.8|  V   |                   |
  |Iil    | Input Leakage      |    |  10|   A  |                   |
  |       |                    |    |    |      |                   |
  |Pins: 62, 63                                                     |
  |       |                    |    |    |      |                   |
  |Voh    | Output High Voltage| 2.4|    |  V   | Iout = -150uA*    |
  |Vol    | Output Low Voltage |    | 0.4|  V   | Iout = - 24mA     |
  |Vih    | Input High Voltage | 2.0|    |  V   |                   |
  |Vil    | Input Low Voltage  |    | 0.8|  V   |                   |
  |Iil    | Input Leakage      |    |  10|   A  |                   |
  |Pins: 16, 33                                                     |
  |Voh    | Output High Voltage| 2.4|    |  V   | Iout = -  3mA     |
  |Vol    | Output Low Voltage |    | 0.4|  V   | Iout = - 24mA     |
  |Pin: 59                                                          |
  |Vol    | Output Low Voltage |    | 0.4|  V   | Iout =  24mA      |
  |Pins: 7, 9, 11, 27-29, 44, 45, 55, 58, 60                        |
  |Vih    | Input High Voltage | 2.0|    |  V   |                   |
  |Vil    | Input Low Voltage  |    | 0.8|  V   |                   |
  |Iil    | Input Leakage      |    |  10|   A  |                   |
  |Pins connected to +5V: 17, 51                                    |
  |Pins connected to GROUND: 1, 34-36, 67, 68                       |
  |Pin used by manufacturing: 52                                    |
  |Pins not used: 8,10,12-15,18-26,42,43,46-50,53,54,56,57,61       |
  |                                                                 |
  |*This source current is supplied by a pull-up resistor.          |

Buffer RAM
A 32-Kbyte static RAM buffer enhances data throughput by buffering
sector data between the Caviar UltraLite and the host system bus.
The buffer is accessed by two channels, each having a separate 16-bit
address and byte-count register. The channels operate simultaneously,
accepting read and write operations from two data paths.

Spindle Motor Driver
A three-phase spindle motor driver is employed. The driver is
controlled by the WD61C12 Servo Controller.

Interface Mode Selection
The PCMCIA SIGNAL OE (pin 9 of the interface connector) is used for
selecting between the ATA and PCMCIA interface modes. OE is sampled
furing power on. To enter ATA mode OE has to b ekept at an electrical
low for a minimum of 20 ms after VCC is stable. If OE is not low
during the entire 20 ms period, the PCMCIA mode will be selected.

J1 Pin Assignments
The Caviar UltraLite drive interfaces with the host I/O bus via a
single 68-pin connector.

PCMCIA and ATA Pin Descriptions

  |Pin  |PCMCIA   |ATA       |I/O   |DESCRIPTION                     |
  |     |MNEMONIC |MNEMONIC  |      |                                |
  |1    |Ground   |Ground    |      |Ground                          |
  |2-6  |D3-D7    |DD3-DD7   |I/O   |Data bits 3 through 7           |
  |7    |CE1      |CS1FX     | I    |Card Enable 1 (Used for host    |
  |     |         |          |      |decoding)                       |
  |8    |A10      |          | I    |Not Used                        |
  |9    |OE       |          | I    |Output Enable (Used             |
  |     |         |          |      |PCMCIA/AT selection)            |
  |10   |A11      |          | I    |Not Used                        |
  |11   |A9       |CS3FX     | I    |Address bit 9 (Used for host    |
  |     |         |          |      |decoding)                       |
  |12   |A8       |          | I    |Not Used                        |
  |13   |A13      |          | I    |Not Used                        |
  |14   |A14      |          | I    |Not Used                        |
  |15   |WE/PGM   |          | I    |Not Used                        |
  |16   |IREQ     |INTRQ     | O    |Interrupt Request               |
  |17   |VCC      |          |      |+5 VDC                          |
  |19   |A-16     |          | I    |Not Used                        |
  |20   |A15      |          | I    |Not Used                        |
  |21   |A12      |          | I    |Not Used                        |
  |22-26|A7-A3    |          | I    |Not Used                        |
  |27-29|A2-A0    |DA2-DA0   | I    |Address bits 2 through 0        |
  |     |         |          |      |(Used for host decoding         |
  |30-32|D0-D2    |DD0-DD2   | I/O  |Data bits 0 through 2           |
  |33   |IOIS16   |IOCS16    | O    |I/O port is 16-bit              |
  |34-35|Ground   |Ground    |      |Ground                          |
  |36   |CDI      |          | O    |Card Detect                     |
  |37-41|D11-D15  |DD11-DD15 | I/O  |Data bits 11 through 15         |
  |42   |CE2      |          | I    |Not Used                        |
  |43   |RFSH     |          | I    |Not Used                        |
  |44   |IORD     |DIOR      | I    |I/O Read                        |
  |45   |IOWR     |DIOW      | I    |I/O Write                       |
  |46-50|A17-A21  |          | I    |Not Used                        |
  |51   |VCC      |          |      |+5 VDC                          |
  |52   |VPP2     |          | I    |Programming and peripheral      |
  |     |         |          |      |supply                          |
  |53-54|A22-A23  |          | I    |Not Used                        |
  |55   |A24      |CSEL      | I    |Address bit 24 (ATA mode slave/ |
  |     |         |          |      |master signal)                  |
  |56   |A25      |          | I    |Not Used                        |
  |57   |RFU      |          | I    |Reserved                        |
  |58   |RESET    |RESET     | I    |Card Reset                      |
  |59   |WAIT     |IORDY     | O    |Extended bus cycle signal       |
  |60   |INPACK   |          | O    |Input Port Acknowledge          |
  |61   |REG      |          | I    |Not Used                        |
  |62   |SPKR     |DASP      | I/O  |Audio Digital Waveform (ATA mode|
  |     |         |          |      |drive active/slave present)     |
  |63   |STSCHG   |PDIAG     | I/O  |Card Statuses Changed (ATA mode |
  |     |         |          |      |passed diagnostics)             |
  |64-66|D8-D10   |DD8-DD10  | I/O  |Data bits 8 through 10          |
  |67   |CD2      |          | O    |Card Detect                     |
  |68   |Ground   |Ground    |      |Ground                          |



General Description
Western Digital's Caviar Ultralite CU140 is a high-performance,
PCMCIA-ATA IDE disk drive designed for today's smallest portable
personal computers. Offering 42.7 Mbyte of formatted capacity, the
CU140 is ideal for design into space constrained sub-notebooks and
companion PCs that require economical storage solutions.

Measuring 10.5 mm in height, the CU140 is 100% form factor compatible
with PCMCIA Type II specifications. The CU140 implements a physical
PCMCIA interface via a 68-pin connector yet retains compatibility
with input from the host and functions in either PCMCIA or AT IDE
modes. This feature allows OEM's to design in a single interface
which supports both flash memory and disk drive storage devices.

The Caviar UltraLite CU140 includes advanced, reduced-power operating
modes to extend battery life. The drive has an average seek time of
less than 19ms, and includes CacheFlow (TM), Western Digital's
exclusive adaptive, multi-segmented, 32-Kbyte caching system.

All Caviar UltraLite CU140 drives are preformatted (low-level), and
defets are mapped out before shipment, ensuring defect-free drives.
Additional features include linear logical/physical address transla-
tion, automatic head parking, embedded servo control data on each
track, and Reed Solomon ECC code.

Western Digital offers reliable, cost effective storage solutions by
integrating design and manufacturing in a process known as Inter-
architecture(TM). The Caviar UltraLite CU140 drive has been designed
along with Western Digital's WD7600LP chip set to provide a complete
system solution for battery-operated portable systems. Interarchitec-
ture(TM) ensures superior performance and reliability.

Western Digital's unique second generation caching evaluates the
way data is read from the drive and adapts - on the fly - to the
optimum read chaching method.

PCMCIA/ATA(TM) Compatibility
Caviar UltraLite drives are physically and electrically compatible
with PCMCIA Type III slots supporting revision 2.0 of the PCMCIA
specification. The command protocol for Western Digital's PCMCIA
drives are fully compatible with the ANSI ATA IDE drive standard and
therefore maintain their compatibility with existing INT13 BIOS

Zoned Recording
The CU140 employs Zoned Recording to increase the data density on the
outer tracks of the drive. The outermost tracks contain 67% more
sectors than the innermost tracks, thereby increasing the total
capacity of the drive.

Advanced Defect Management
The Caviar UltraLite is preformatted (low level) at the factory and
comes with a full complement of defect management functions.
Extensively tested during the manufacturing process, media defects
found during intelligent burn-in are mapped out with Western
Digital's high performance defect management technique. No modifica-
tions are required before installation.

Dual Drive Operation
The Caviar UltraLite supports dual drive operation in the ATA IDE
mode by a means of a "daisy chain" cable assembly and the Cable
Select (CSEL) signal. The Caviar UltraLite usesthis signal to de-
termine whether it is a Master or Slave.

Universal Data Translation
The Caviar UltraLite provides a linear disk address translator to
convert logical sector addresses to physical sector addresses which
provides for easy installation and compatibility with numerous drive

Guranteed Compatibility
Western Digital performs extensive testing in its Functional
Integrity Test Labs (FIT Lab.) to ensure compatibility with all 100%
AT-compatible computers and standard operating systems.

 Seek Time
       |                                  | UT-140 |
       |Track-to-Track         msec. typ. |   5    |
       |Average                msec. typ. | Sub-19 |
       |                       msec. max. |  40    |
       |Average Latency        msec.      |   6.67 |

WD61C23 Winchester Disk Controller/Buffer Manager
Electronic component of the Caviar UltraLite:

The WD61C23 integrates a high performance, low cost Winchester
formatter/controller, CRC/ECC generator/checker, host interface and
buffer manager into a single, 100-pin SQFP device. The CRC/ECC
generator/checker calculates ECC for the data field. The host inter-
face directly connects to the host system bus via internal 24 mA
drivers. The buffer manager controls the buffer RAM and handles the
arbitration between the host interface and drive controller.

Defect Management
Every Caviar UltraLite drive undergoes factory-level intelligent burn
in, which throughly tests for and maps out defective sectors on the
media before the drive leaves the manufacturing facility. Following
the factory tests, a primary defect list is created which contains
the cylinder, head, and sector numbers for all defects.

Defects managed at the factory are sector slipped. Grown defects that
can occur in the field are handled by relocation to spare sectors on
the inner cylinders of the drive.

Format Characteristics
The Caviar UltraLite is shipped from the factory preformatted (low
level) with all defects mapped out. This eliminates the need for the
end user to enter defects during installation. No additional low-
level formatting is required, although a high-level format must still
be performed.

To provide compatibility with existing industry standard defect
management utility programs, the Caviar UltraLite supports logical
format. When the host issues the Format Track command, the Caviar
UltraLite performs a logical version of this command in response to
the host's interleave table request for good and bad sector marking
or assign/unassign the sector to/from an alternate sector.

If the host issues a Format Track Command during normal operating
modes, the data fields of the specified track are filled with a data
pattern of all zeros. The interleave table identifies any bad sectors
on a given track. The interleave table must contain all appropriate
number of bytes of data. There are two bytes per sector for each
entry in the interleave table. The first byte marks the sector as
good and bad. The first byte is set to 00H to indicate a good sector,
to 80H to indicate a bad sector, to 20H to unassign the alternate
sector, or to 40H to assign the sector to an alternate location. The
second byte designates the logical sector ID number.

Error Register
The Error Register contains an error code that indicate a particular
type of failure. The register contains a valid error code only if the
Statur Register error bit 0 is set. The only exceptions are power-up
and issuance of a reset or diagnostic command. In these cases the
Error Register contents are valid regardless of the condition of the
Status Register's error bit. These two exceptions cause the following
error values:

      01 = No error

      02 = Not applicable

      03 = Buffer RAM error

      04 = WD61C23 register error

      05 = Microprocessor internal RAM error or ROM checksum error

      8X = Slave drive failed

If a slave drive is present and has failed its diagnostic, 80H is
ORed with the master drive's status bits. To read the slave's error
code, the host should set the D bit in the SHD Register. In all other
cases the Error Register bits are defined as follows when asserted.

         |                BIT POSITIONS                   |
         | 7   | 6   | 5   | 4   | 3   | 2   | 1   | 0    |
         | BBD | ECC | 0   | IDNF| 0   | AC  | TK0 | DAMNF|
         | BBD       Bad Block Detected                   |
         | ECC       Error Correction Code (Uncorrectable |
         |           error detected)                      |
         | IDNF      ID Not Found (Target sector could not|
         |           be found                             |
         | AC        Aborted Command                      |
         | TK0       Track 0 (Unable to find a valid track|
         |           0)                                   |
         | DAMNF     Data Address Mark Not Found          |

Write Precompensation Register
The Write Precompensation Register is ignored during normal write
operations since the Caviar UltraLite automatically determines the
proper write precompensation. The contents of this register are only
used by the Set Buffer Mode command.



 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
    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:

- 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

- 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.


- 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

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
    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-
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.

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

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 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.

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.

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.

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.

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.

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

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.

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