Hard Drive: WESTERN DIGITAL: AC-420400 CAVIAR 20416MB 3.5"/SL ATA66 ULTR
A C - 4 2 0 4 0 0 C A V I A R WESTERN DIGITAL
Native| Translation
------+-----+-----+-----
Form 3.5"/SLIMLINE Cylinders |16383| |
Capacity form/unform 20416/ MB Heads 8| 16| |
Seek time / track 9.0/ 2.2 ms Sector/track | 63| |
Controller IDE / ATA66 ULTRA Precompensation
Cache/Buffer 2000 KB ADAPTIVE Landing Zone
Data transfer rate 21.000 MB/S int Bytes/Sector 512
66.600 MB/S ext UDMA4
Recording method operating | non-operating
-------------+--------------
Supply voltage 5/12 V Temperature *C 5 55 | -40 65
Power: sleep 0.1 W Humidity % 8 90 | 5 95
standby 0.1 W Altitude km |
idle 8.7 W Shock g 10 | 75
seek W Rotation RPM 5400
read/write 8.7 W Acoustic dBA 40
spin-up W ECC Bit REED SOLOMON
MTBF h 750000
Warranty Month 36
Lift/Lock/Park YES Certificates
General
WESTERN 8.4GB BARRIER
8.4 GB Capacity Barrier - 3.5-inch EIDE Hard Drives
----------------------------------------------------
Some system BIOSs and operating systems have limitations associated
with large capacity hard drives. There are several PC components that
have an EIDE hard drive capacity limitation at approximately 8.4 GB.
These limitations apply to any hard drive that reports an EIDE
capacity of 16320 cylinders x 16 heads x 63 sectors per track or
larger. The following is a discussion of how these limitations affect
the system BIOS Interrupt 13 functions, the operation of EIDE hard
drives, and operating systems.
System BIOS Interrupt 13 Functions
----------------------------------
Interrupt 13 (INT 13) Functions:
INT 13 Function 8 is the traditional method used by the system BIOS
to access hard drives using cylinders, heads, and sectors per track
(CHS). Identify Drive words 1, 3, and 6 contain these values. The
maximum values the BIOS can report (1024 cylinders 256 heads, and 63
sectors) have been exceeded by the 8.4 GB and larger hard drive
capacities.
Because some operating systems do not function properly with 256
heads, all system BIOSs report a maximum number of 255 heads. There
are times when a hard drive is large enough that INT 13 Function 8
could report 1024 cylinders. However, it is common for only 1023
cylinders to be reported.
The remaining diagnostic cylinder is not made accessible through INT
13 function calls.
Extended INT 13 Functions:
To utilize the full capacity of hard drives larger than 8.4 GB, the
system BIOS must use extended INT 13 functions. To recognize the full
capacity of hard drives larger than 8.4 GB, extended INT 13 functions
use Identify Drive words 60 and 61 rather than words 1, 3, and 6.
Many system BIOSs do not support extended INT 13 functions. DOS 6.22
and earlier versions do not recognize or utilize these extended
functions even if they exist in the BIOS. Windows 95, Windows 98,
and boot disks created with Windows 95, are capable of utilizing
these functions and recognizing hard drives larger than 8.4 GB.
WDTBLCHK Version 2.00 and later can be used to determine if these
functions are present.
EIDE Hard Drives System BIOSs and operating systems check the
capacity of EIDE hard drives by issuing an Identify Drive command.
The hard drive reports the capacity in two ways:
1. The number of cylinders, heads, and sectors per track (in words 1,
3, and 6).
2. The total number of addressable sectors (in words 60 and 61).
Most EIDE 8.4 GB hard drives report their capacity as 16383
cylinders, 16 heads, and 63 sectors per track in Identify Drive
words 1, 3, and 6. This results in a total number of addressable
sectors of 16,514,064 (8455 MB). 8.4 GB is the largest capacity
that can be reported with words 1, 3, and 6 because the maximum
value these words can hold are 16383x16x63.
To determine the true capacity of hard drives larger than 8.4
GB, the system BIOS must access Identify Drive words 60 and 61 and
use the total addressable sectors.
System BIOS Limitations at 8.4 GB
---------------------------------
Many BIOSs do not properly support 8.4 GB and larger hard drives. We
recommend using EZ-Drive 9.06W or later. EZ-Drive 9.06W or later
supports extended INT 13 functions which allows the BIOS to access
the full capacity of 8.4 GB and larger hard drives. EZ-Drive 9.06W
can be downloaded from Western Digital's web site at
www.westerdigital.com
Some of the BIOS issues that may be encountered with 8.4 GB or larger
hard drives are: 1. Reporting 0 Heads in INT 13 Function 8.
Some BIOSs attempt to use translated geometry but incorrectly report
0 heads in INT 13 Function 8 instead of 255 heads. If Fdisk is run on
these systems, it initially appears to function normally. However, a
corrupted partition is created which incorrectly reports the drive
has 0 heads. DOS hangs, even when booted from a floppy, as soon as it
detects this partition.
To correct this issue: - Boot to a bootable non-DOS based floppy. EZ-Drive can be used for this purpose.
- Boot to the EZ-Drive diskette and set up the drive using EZ-Drive. This repartitions and formats the drive correctly so that the system can boot properly.
Failure to Translate or Reporting Much
--------------------------------------
Lower Capacities. Some BIOSs will not translate an 8.4 GB hard drive,
or will report a capacity significantly less than 8.4 GB. In some
cases, an 8.4 GB or larger drive causes INT 13 Function 8 to revert
back to what appears to be a 528 MB or less limitation. The solution
is to either obtain a BIOS upgrade if possible, or use EZ-Drive
9.06W.
Hang During Boot
----------------
Some systems hang after power on when auto-detecting an 8.4 GB hard
drive. This hang does not disappear until a less than 8.4 GB drive
type is selected in CMOS, making it impossible to utilize the full
capacity of the hard drive. The solution is to select a User Defined
type that is less than 8.4 GB, and use EZ-Drive 9.06W to set up the
hard drive.
POST Error During Boot
----------------------
In some systems with proprietary BIOSs you may encounter errors
during POST or a failure to boot properly. If this happens it may be
necessary to use the Alternate Jumper Settings shown below and set
up the hard drive using EZ-Drive. The Alternate Jumper Settings are
used to force the drive to report 4092 cylinders in Identify Drive
word 1, but still report the true capacity in words 60 and 61. This
allows EZ-Drive and the extended INT 13 functions to recognize
the true capacity of the hard drive.
240 Head BIOS Translation
-------------------------
Many BIOSs report a maximum of 240 heads in INT 13 Function 8, giving
a limitation of 7.9 GB (1024x240x63). Some of these BIOSs still
support extended INT 13 functions. Windows 95 and Windows 98, which
utilize the extended INT 13 functions, recognize the full 8.4 GB or
larger capacity. DOS 6.x and Windows 3.x are limited to 7.9 GB
because they do not utilize the extended INT 13 functions.
Operating System Limitations at 8.4 GB
--------------------------------------
1. DOS 6.x and Windows 3.x. These operating systems do not support
extended INT 13 functions so they are dependent on the INT 13
Function 8 BIOS limitation of the system.
DOS is limited to a maximum of 1024 cylinders, 255 heads, and 63
sectors per track (16,450,560 addressable sectors or 8423 MB).
Therefore, the maximum values DOS can recognize in Identify Drive
words 1, 3, and 6 are 16320x16x63 (8423 MB). DOS cannot utilize the
full capacity of hard drives larger than 8.4 GB.
Single Drive Alternate Jumper Settings
--------------------------------------
Dual (Master) Drive Alternate Jumper Settings Dual (Slave) Drive
Alternate Jumper Settings
Windows 95 & Windows 98
-----------------------
Windows 95 and Windows 98 support extended INT 13 functions, and
therefore support 8.4 GB and larger hard drives. However, if the
system BIOS does not support extended INT 13 functions, then Windows
95 and Windows 98 are limited by the system BIOS's barrier and
cannot support the full capacity of 8.4 GB and larger hard drives.
To ensure that Windows 95 and Windows 98 recognize the full capacity
of 8.4 GB and larger hard drives, the system BIOS must support
extended INT 13 functions.
Windows NT 4.0
--------------
Windows NT 4.0 recognizes the full capacity of hard drives up to the
8.4 GB limit in Identify Drive words 1, 3, and 6. Service Pack 3 is
required to recognize hard drives larger than 8.4 GB. Without Service
Pack 3, hard drives larger than 8.4 GB are treated as the capacity
shown in Identify Drive words 1, 3, and 6 regardless of what is
reported in words 60 and 61 (8.4 GB max.).
The first partition in Windows NT 4.0 is limited to 4 GB. During the
initial setup, it appears that the full capacity of the hard drive
is not recognized. After installing Windows NT, use the Disk
Administrator utility that comes with Windows NT to create additional
partitions to utilize the full capacity of the 8.4 GB hard drive.
Windows NT 4.0 does not require extended INT 13 functions to
recognize the full capacity of the hard drive. Windows NT operates
the same regardless of whether the extended INT 13 functions are
present.
OS/2 Warp 4.0
-------------
As of the date of this document, OS/2 Warp cannot be installed
properly with 8.4 GB and larger hard drives. IBM is currently
working on a patch to correct this.
Novell Netware 4.11
-------------------
Novell Netware 4.11 recognizes the full capacity of hard drives up to
the 8.4 GB limit in Identify Drive words 1, 3, and 6. Since Novell
does not check Identify Drive words 60 and 61, hard drives larger
than 8.4 GB are treated as the capacity reported in words 1, 3, and 6
(8.4 GB maximum).
Novell Netware does not use extended INT 13 functions, so it cannot
support larger than 8.4 GB hard drives.
Conclusion
----------
The limitations of your system BIOS and your operating system
combined determine your overall system limitation. For example, if
your operating system recognizes extended BIOS functions, but
your system BIOS has a 2.1 GB hard drive barrier, you are limited to
your system BIOS's 2.1 GB hard drive barrier. Conversely, if your
operating system does not recognize extended BIOS functions, but
your system BIOS supports 8.4 GB hard drives, you are limited to your
operating system's capability. Your system limitation is based on the
lowest functioning barrier.
To utilize the full capacity of 8.4 GB and larger hard drives, your
system BIOS and operating system must support extended INT 13
functions. Since it is difficult to determine if your system
BIOS supports 8.4 GB or larger hard drives, we recommend using
EZ-Drive 9.06W or later. EZ-Drive 9.06W or later can determine
whether or not your system BIOS properly supports the full capacity
of your hard drive. If it does not, EZ-Drive installs EZ-BIOS on the
boot sector of the hard drive to support the full capacity of your
8.4 GB or larger hard drive. If your system BIOS supports your hard
drive, EZ-Drive does not install EZ-BIOS.
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