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Enhanced IDE (Enhanced Integrated Drive Electronics) is the
latest standard used to handle communication between hard drives and
the central processing unit. As with its predecessor, Enhanced
IDE consists of interface controller electronics that reside on the
hard drive, along with some important new features required to keep
pace with the continually evolving computer industry.
Western Digital has been at the forefront in developing hard
drive interfaces since 1984, beginning with its design of the ST506
interface hard disk controller used by IBM in the PC/AT systems.
Subsequantly, with the IDE interface that Western Digital and Compaq
produced in 1986, the interface controller electronics were
incorporated into the design of the hard drive rather than as a
separate controller. This new technology became the industry
standard for primary mass storage solutions, because of its
ease-of-use, compatibility, and low cost of connection.
Expansion in the industry triggered constant change, such as
improvements to processor speeds and bus technologies, and the advent
of CD-ROM and other peripherals, not to mention the quest to
continually improve the capacity of hard drives.
To meet these requirements, Western Digital developed
Enhanced IDE, expanding upon the key attributes of IDE by:
- Providing a solution to hard drive capacity barriers
- Increased data transfer rates
- Improved device support
- Providing support for peripherals
Breaks the drive capacity Barriers
Enhanced IDE overcomes drive capacity barriers. A
typical system BIOS dated before August 1994 does not recognize drives
larger than 528 MB as a result of the cylinder, head, and sector
definitions of both BIOS Interrupt 13 and the IDE interface.
If your system BIOS cannot recognize hard drives larger than 528 MB,
you can use one of the following solutions:
- Install EZ-Drive, an installation software package that
is used to overcome system BIOS limitations.
- Contact your system or BIOS manufacturer to obtain an
updated BIOS, in the form of a BIOS chip upgrade or an EIDE
controller card with onboard BIOS.
Another barrier exists in some computer systems built before
early 1996 which do not support hard drives with more than 4095
cylinders (hard drives larger than 2.1 GB). These BIOSs
can only recognize drive capacities up to 2.1 GB. If your
operating system shows your drive as having a much smaller capacity
than it does, use EZ-Drive to overcome the 2.1 GB BIOS limitation.
EZ-Drive can be downloaded from Western Digital's web site at www.westerndigital.com.
If your system locks up at boot time when the BIOS detects a
drive with 4095 or more cylinders, the following solutions are
available:
- Check the IDE interface cable, power supply cable, and
the jumper settings, turn on your system power, and then try to
enter your CMOS setup and set the drive to auto config.
- If your system still does not respond, disconnect the IDE
interface cable from the system, go into CMOS and select a user
defined type and enter the parameters 1023 cylinders, 16 heads,
and 63 sectors. Select Type 9 if you don't have a user
defined drive type.
- Reconnect you IDE interface cable to the system and
install EZ-Drive.
- If you don't have a user defined or Type 9 drive type,
use one of these solutions:
- Upgrade your system BIOS
- Install an EIDE controller card with an
onboard BIOS supporting hard drives larger than 2.1 GB.
- Rejumper the drive as described in the
Western Digital Installation Guide. This information is also
available on Western Digital's web site.
Increases Data Throughput
Today's local bus architacture has become the industry
standard as end users continue to demand enhanced system performance.
Maximum hard drive performance can also be obtained by taking
advantage of local bus attachment.
Expanding upon the standard IDE interface timings of 2-3
MB/s, the Small Form Factor Committee (SFF) defined new PIO, DMA, and
Ultra DMA timings for hard drive operations in local bus environments.
EIDE modes offer great improvement over traditional IDE host
transfers.
Supports Four IDE Devices
Enhanced IDE takes advantage of the fact that today's
operating systems support both primary and secondary IDE channels.
Because the original AT architecture was defined only for hard drives,
dual channel IDE provides the opportunity to expand peripheral
attachments beyond hard drives. Adding a second low-cost IDE
channel was a simple hardware change that has made it possible to
support as many as four IDE devices on two channels. BIOS
support is also required to enable this enhanced connectivity
capability.
Supports IDE Peripherals and Non-Disk Peripherals
Dual channel IDE via dual IDE connectors provides the
capability to support both a slow speed and a high speed channel.
This makes it possible to connect both fast IDE disk peripherals and
slow IDE non-disk peripherals such as CD-ROM and tape. To this
purpose Western Digital authored the AT Attachment Packet Interface (ATAPI).
ATAPI supplements the definitions of the ATA mass storage peripheral
found in the ATA specification and is compatible with existing ATA
hardware, encouraging non-disk peripheral suppliers to design products
according to a compatible, standardized interface.
Western Digital and the IDE Interface - Building upon
Expertise
Western Digital's Enhanced IDE program evolved from the
company's storage expertise within the personal computer marketplace.
Since 1984, Western Digital has set the standards for AT hard drive
controllers. Western Digital has set the standards for AT hard
drive controllers. Western Digital continues to lead the
industry by providing the Enhanced IDE interface as the solution to
meet the needs of today's demanding PC environment.
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