A C - 3 4 3 0 0 C A V I A R WESTERN DIGITAL Native| Translation ------+-----+-----+----- Form 3.5"/SLIMLINE Cylinders | 8896| | Capacity form/unform 4304/ MB Heads 5| 15| | Seek time / track 11.0/ ms Sector/track | 63| | Controller IDE / ATA4 Precompensation Cache/Buffer 256 KB Landing Zone Data transfer rate 8.000 MB/S int Bytes/Sector 512 33.300 MB/S ext UDMA Recording method GCR8/9PRML operating | non-operating -------------+-------------- Supply voltage 5/12 V Temperature *C 5 55 | -40 60 Power: sleep 1.3 W Humidity % 5 55 | 5 95 standby 1.6 W Altitude km -0.300 3.000| -0.300 12.000 idle 5.6 W Shock g 10 | 150 seek 7.2 W Rotation RPM 5400 read/write 5.6 W Acoustic dBA 40 spin-up 18.2 W ECC Bit 72BIT REED SOLOMON,SMART MTBF h 350000 Warranty Month 36 Lift/Lock/Park YES Certificates CE(EU),EN50082-1,FCC,IEC95... ********************************************************************** L A Y O U T ********************************************************************** WESTERN AC11600/23200 TECH. REFERENCE MANUAL 79-860028-000 6/26/97 +---------------------------------------------------------+ | |XX | |XX J2 | |XX Inter- | |XX face | |XX | |.X | |XX | |XX | |XX | |XX | |X1 | |+-+ | || |J8 | |+-1 | |XX Power | |XX J3 +---------------------------------------------------------+ 1 J2 J8 J3 +39------------------------------------1++9-7-5-3-1++-------+ |o o o o o o o o o o o o o o o o o o o o||o o o o o||O O O O| |o o o o o o o o o o o o o o o o o o o||o o o o o||4 3 2 1| --+40------------------------------------2+10-8-6-4-2+++-+-+-++---- | | | +12V (Pin 20 keyed) | | +- GND | +--- GND +----- +5V ********************************************************************** J U M P E R S ********************************************************************** WESTERN AC11600/23200 TECH. REFERENCE MANUAL 79-860028-000 6/26/97 Jumper setting ============== J8 Master/Slave/Cable Select Configuration ------------------------------------------- +5-3-1+ Single (Neutral Position) |xxx o| Factory default. The jumper in this position has no effect |o o o| on single hard drive configurations. +6-4-2+ +5-3-1+ Cable Select +5-3-1+ Master Drive |o o X| option. |X o o| Configuration |o o X| |X o o| (Dual Drives) +6-4-2+ +6-4-2+ +5-3-1+ Slave Drive |o X o| Configuration |o X o| (Dual Drives) +6-4-2+ The Caviar can be assigned as either a single, master, or slave drive. 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 drive is compatible in dual installations with other IDE drives that support a master/slave configuration. Jumper Settings --------------- The Caviar drive has a jumper block (J8) located next to the 40-pin connector on the drive. The Caviar can be assigned as either a single, master, or slave drive. WD Caviar drives are shipped with a jumper shunt in the neutral storage position (across pins 5 and 3). The additional fouor pins on the 10-pin connector are reserved for future enhancements. Single Drive Mode - If you are installing the Caviar drive as the only hard drive in the system, leave the jumper in the neutral storage position. Jumpers are not required for single drive installations. Note that even with no jumper installed, the Caviar checks the DRIVE ACTIVE/SLAVE PRESENT (DASP) signal to determine if a slave IDE drive is present. If you have a dual installation (two hard drives), you must designate one of the drives as the master and the other as the slave drive. The jumper pins on the J8 connector need to be configured for the dual installation. Master Drive Mode - To designate the drive as the master, place a jumper shunt on pins 5-6. With the Caviar configured as the master drive, the Caviar assumes that a slave drive is present. The jumper on pins 5-6 is optional if the slave drive follows the same protocol (Common Access Method AT Bus Attachment) as the WD Caviar drive. Slave Drive Mode - To designate the drive as the slave, place a jumper shunt on pins 3-4. When the Caviar is configured as the slave drive, the Caviar delays spin up for three seconds after power-up reset. This feature prevents overloading of the power supply during power-up. Cable Select (CSEL) - Caviar also supports the CSEL signal on the drive cable as a drive address selection. Place a jumper shunt on pins 1-2 to enable this option. When enabled, the drive address is 0 (Master) if CSEL is low, or 1 (Slave) if CSEL is high. Do not install the CSEL jumper shunt when installing the Caviar drive in systems that do not support the CSEL feature. J3 DC Power and pin connector assignments ------------------------------------------- +------------+ pin 1 +12 V | 4 3 2 1 | pin 2 GND +------------+ pin 3 GND pin 4 + 5 V Alternate Jumper Settings for Drives Larger than 2.1 GB ======================================================= On initial boot, the system BIOs may lock up on drives that have more than 4095 cylinders (driver larger than 2.1 GB). Alternate jumper setting have been provided for the Caviar drives that are larger than 2.1GB to overcome this system BIOS limitation. These jumper settings cause the drive to report 4092 cylinders (instead of the usual 6296, 8896 or 10672) in Word 1 of the Identify Drive data. The true capacity is still reported in Word 54 and Word 60-61. All other Identify Drive data remains the same. Special software is required for DOS and Windows operating systems to utilize the full capacity of drives larger than 2.1 GB. +5-3-1+ Single Drive +5-3-1+ Master Drive |X X o| Configuration |X o X| Configuration |X X o| |X o X| (Dual Drives) +6-4-2+ +6-4-2+ +5-3-1+ Slave Drive |o X X| Configuration |o X X| (Dual Drives) +6-4-2+ ********************************************************************** I N S T A L L ********************************************************************** WESTERN AC11600/23200 TECH. REFERENCE MANUAL 79-860028-000 6/26/97 Notes On Installation ===================== Installation direction ---------------------- horizontally vertically +-----------------+ +--+ +--+ | | | +-----+ +-----+ | | | | | | | | | +-+-----------------+-+ | | | | | | +---------------------+ | | | | | | | | | | | | | | | | | | +---------------------+ | +-----+ +-----+ | +-+-----------------+-+ +--+ +--+ | | | | +-----------------+ The drive will operate in all axis (6 directions). Orientation ----------- The Caviar can be mounted in the X, Y, or Z axis depending upon the physical design of your system. It is recommended that the drive be mounted with all four screws grounded to the chassis. Screw Size Limitations ---------------------- The Caviar is mounted to the chassis using four 6-32 screws. Recommended screw torque is 5 in-lb. Maximum screw torque is 10 in-lb. Caution: Screws that are too long will damage circuit board components. The screw must engage no more than six threads (3/16 inch). Side mounted screws should engage a maximum of .188 inches (3/16"). Bottom mounted screws should engage a maximum of .250 inches (1/4"). Side mounting: Use four metal screws. Top face mounting: Use four metal screws. Determining Your Configuration ------------------------------ You can configure the Caviar in one of two ways: 1. The drive is cabled directly to a 40-pin connector on the motherboard, or 2. The drive is cabled to an adapter card mounted in one of the expansion slots in the computer. Both configurations use a 40-pin host interface cable. If you are using the Caviar drive as one of two hard disk drives in the computer (dual installation), you may use either configuration. In dual installations, you must use a 40-pin host interface cable with three connectors and daisy-chain the two drives to the motherboard or adapter card. Mounting the Drive ------------------ For dual installations, it is usually easier to completely install one IDE drive in the lower position first. The order of IDE drives is unimportant if you are using two Western Digital drives. As explained previously, one must be jumpered as the master drive and the other as the slave drive. When installation is complete, the drives are daisy-chained together. Cabling and Installation Steps ------------------------------ Make sure your interface cable is no longer than 18 inches (including daisy chaining) to minimize noise that is induced on the data and control buses. When connecting two drives, use a daisy-chain cable that has three 40-pin connectors. Connectors should be placed no more than six inches from the end of the cable. If only one drive is connected, it should be placed on the end of the cable. Caution: You may damage the Caviar drive if the interface cable is not connected properly. To prevent incorrect connection, use a cable that has keyed connectors at both the drive and host ends. Pin 20 has been removed from the J2 connector. The female connector on the interface cable should have a plug in position 20 to prevent incorrect connection. Make sure that pin 1 on the cable is connected to pin 1 on the connectors. The order in which you perform the following steps will vary depending on your system. 1. Attach the end of the 40-pin interface cable to the 40-pin J2 connector on the back of the Caviar hard drive. For dual installations, connect the two drives together by using a three-connector interface cable. Match the orientation of pin socket 1 on the 40-pin IDE cable to pin 1 on the connector. 2. Thread the cable through the empty drive bay and slide in the Caviar drive. 3. Mount the Caviar drive in the drive bay using four 6-32 screws. Be sure to use the correct size screws. Do not install the screws past six threads (3/16 inch). Screws that are too long will damage the Caviar drive. For proper grounding be sure to use ALL four screws. Interface Pin 39 HDASP (I/O) Drive Active/Slave Present ------------------------------------------------------- This open collector output is a time-muliplexed signal indicating drive active or slave present. At reset, this signal is an output from the slave drive and an input to the master drive, showing that a slave is present. For all times other than reset, HDASP- is asserted by the master and slave drives during command execution. Grounding --------- It is recommended that the drive be mounted with all four screws in the side grounded to the chassis. The drive must be grounded with at least one mounting screw. Power Connectors and Cables --------------------------- Power Connector 4-pin AMP P/N 84069-1 or equivalent Mating Connector Body AMP 1-480424-0 or equivalent Pins AMP 60619-4 or equivalent Power Cable Wire Gauge 18 AWG (or heavier) ********************************************************************** F E A T U R E S ********************************************************************** WESTERN AC11600/23200 TECH. REFERENCE MANUAL 79-860028-000 6/26/97 General Description ------------------- Western Digital's latest generation of high-performance WD Caviar drives, the AC11600/23200/34300 and AC35100 Enhanced IDE hard drives, set new standards for storage, performance and reliability. With storage capacities up to 5.1 gigabytes, these workhorse WD Caviar drives are engineered to handle today's most storage-intensive desktop, workstation, multimedia and internet applications. Defect Management ----------------- Every Caviar undergoes factory-level intelligent burn in, which thoroughly 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. The list 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 mapped out by relocation to spare sectors on the inner cylinders of the drive. Advanced Product Features ------------------------- - CacheFlow5 - Western Digital's unique, fifth-generation caching algorithm evaluates the way data is read from and written to the drive and adapts on-the-fly to the optimum read and write caching methods. CacheFlow5 minimizes disk seeking operations and the overhead due to rotational latency delays. CacheFlow5 supports sequential write cache. Incorporating write cache with other CacheFlow5 features enables the user to cache both read data as well as write data. Multiple writes can now be held in the cache and then written collectively to the hard disk later. Data is held in the cache no longer than the time required to write all cached commands to the disk. CacheFlow5 constantly evaluates not only the size of the read data request but the type of data request, that is, whether the data request is sequential, random, or repetitive. CacheFlow5 selects the appropriate caching mode for optimum system performance. - Advanced Host Transfer - The AC11600/23200/34300/35100 support Mode 2 Ultra DMA/33 (33.3 MB/s), Mode 4 PIO (16.6 MB/s) and Mode 2 multi-word DMA (16.6 MB/s) as defined by the ATA-4 standards. To achieve Mode 4 PIO burst transfers, hard disk drives must be able to throttle the host via the IORDY signal. Systems typically require a high-speed VL or PCI local bus in order to support Mode 4 PIO. - High-Speed DMA Capability - DMA Read and DMA Write commands are ATA-4 compatible and provide significant improvement in CPU bandwidth over conventional PIO data transfers. The system CPU is free to accomplish other tasks while the Caviar drive transfers data directly to/from system memory. - Power Conservation - The AC11600/23200/34300/35100 supports the ATA-4 power management command set. This command set allows the host to reduce the power consumption of the drive by issuing a variety of power management commands. - Block Mode - ATA-4 compatible Read Multiple and Write Multiple commands are supported. Block mode increases overall data transfer rates by transferring more data between system interrupts. - Logical Block Addressing (LBA) - The AC11600/23200/34300/35100 support both LBA and CHS-based addressing. LBA is included in advanced BIOS and operating system device drivers and ensures high-capacity disk integration. - Automatic Head Parking - Head parking is automatic with Caviar drives. On power down, the heads retract to a safe, non-data landing zone and lock into position, improving data integrity and resistance to non-operational shock. - Advanced Defect Management - These Caviar drives are preformatted (low-level) at the factory and come with a full complement of automatic 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 modifications are required before installation. - Embedded Servo Control - These Caviar drives feature an embedded servo concept as the means of providing sampled position feedback information to the head position servo system. Servo bursts are located along a radial path from the disk center, ensuring that head positioning data occurs at constant intervals. This high sampling rate supports the high frequency servo bandwidth required for fast access times as well as highly accurate head positioning. The embedded servo concept provides the means of generating accurate feedback information without requiring a full data surface as would a dedicated servo control concept. - Dual Drive Operation - These Caviar drives support dual drive operation by means of a "daisy chain" cable assembly and configuration options for master or slave drive designation. They also supports Cable Select (CSEL) for master or slave designation. - Universal Address Translation - These Caviar drives provide a linear disk address translator to convert logical sector addresses to physical sector addresses which provides for easy installation and compatibility with numerous drive types. - Guaranteed Compatibility - Western Digital performs extensive testing in its Functional Integrity Test Lab (FIT Lab) to ensure compatibility with all 100% AT-compatible computers and standard operating systems. - Reed Solomon ECC On-the-Fly - The Caviar implements Reed Solomon error correction techniques to obtain extremely low read error rates. This error correction algorithm corrects errors on-the-fly without any performance penalties. It allows for hardware corrections of up to a 72-bit error span on-the-fly. - Automatic Defect Retirement - If the Caviar drive detects a defective sector while writing, it automatically relocates the sector without enduser intervention. Format Characteristics ---------------------- The Caviar is shipped from the factory preformatted (low-level) with all the known defects mapped out. In order to be compatible with existing industry standard defect management utility programs, the Caviar supports the logical format command. When the host issues the Format Track command, the Caviar 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 the Format Track Command during normal operating modes, the data fields of the specified track are filled with a data pattern of all zeros. The Format Track Command can be used to mark/unmark bad sectors, and reassign unrelocated sectors. Automatic Defect Retirement --------------------------- The automatic defect retirement feature automatically maps out defective sectors while writing. If a defective sector appears, Caviar finds a spare sector. Error Recovery Process ---------------------- The Caviar has four means of error recovery: - ECC On-the-Fly - Read/Write Retry Procedure - Extended Read Retry Procedure - Extended (Firmware Assisted) ECC Correction and Realocation ECC On-the-Fly - If an ECC error occurs, the Caviar attempts to correct it on-the-fly without retries. Data can be corrected in this manner without performance penalty. Read/Write Retry Procedure - This retry procedure is used by all disk controller error types. If this procedure succeeds in reading or writing the sector being tried, then recovery is complete and the controller continues with the command. Each retry operation also checks for servo errors. This procedure ends when error recovery is achieved or when all possible retries have been attempted. Extended Read Retry Procedure - This retry procedure tries combinations of positive/negative track offsets, and data DAC manipulations to recover the data. This retry procedure is applicable only to read data recovery. The Read/Write Retry procedure is used to perform the actual retry operation. When an extended retry operation has been successful, the controller continues with the command. The controller ensures that any changes in track offset or data DAC settings that exist are cleared before the command continues. Extended (Firmware Assisted) ECC - If an ECC error is too large to correct using ECC on-the-fly, the Caviar can attempt to correct the error using Extended Error Correction. This allows correction of large ECC errors that ECC on-the-fly cannot correct. However, the Extended Error Correction process takes more time than ECC on-the-fly to return the corrected data. REED SOLOMON ECC On-the-Fly --------------------------- The WD Caviar implements Reed Solomon error correction techniques in hardware to reduce the uncorrectable read error rate. This allows a high degree of data integrity with no impact on the drive's performance. Because on-the-fly corrected errors do not require the drive's firmware to assist with error correction, they are invisible to the host system. To obtain the ECC check byte values, each byte within the sector is interleaved into one of three groups, where the first byte is in interleave 1, the second byte is in interleave 2, the third byte is in interleave 3, the fourth byte is in interleave 1, and so on. Interleaving and the ECC formulas enable the drive to detect where the error occurs. A maximum of one byte can be corrected in each interleave without firmware assistance. Firmware Assisted ECC ---------------------- With firmware assisted ECC, a maximum of 3 random bytes can be corrected in each interleave. In this case, a 113-bit single-burst error span is the maximum that is always correctable with firmware assistance because the entire error span will never occupy more than three bytes in each interleave. Universal Address Translation ----------------------------- The Caviar implements linear address translation. The translation mode and translated drive configuration are selected by using the Set Drive Parameters command to issue head and sector/track counts to the translator. Caviar supports universal translation. Therefore, any valid combination of cylinder, head, and SPT can be assigned to the drive as long as the total number of sectors is not greater than the physical limits. The product of the cylinder, head and sectors/track counts must be equal to or less than the maximum number of sectors available to the user. The max. number of sector per drive follows: AC11600 - 3,173,184 AC23200 - 6,346,368 AC34300 - 8,406,720 AC35100 - 10,085,040 Each sector consists of 512 bytes. The values in the Sector Count Register and the SDH Register determine the Sectors Per Track (SPT) and heads. Regardless of the values of the SPT and the heads, Caviar is always in the translation mode. Power Conservation ------------------ The AC11600/23200/34300/35100 support the ATA-4 power management commands that lower the average power consumption of the disk drives. For example, to take advantage of the lower power consumption modes of the drive, an energy efficient host system could implement a power management scheme that issues a Standby Immediate command when a host resident disk inactivity timer has expired. The Standby Immediate command would cause the drive to spin down and enter a low-power mode after a 10 sec. delay. Subsequent disk access commands would cause the drive to spin up and execute the new command. To avoid excessive wear on the drive due to the starting and stopping of the HDA, the host's disk inactivity timer should be set to no shorter than ten minutes. High-Speed DMA Capability ------------------------- By engaging an ATA-4 compatible, Mode 2 multi-word DMA, the host CPU bandwidth is increased because the peripheral data transfer burden is off-loaded to the system's DMA channel. With the exception of DMA data transfers, which are limited to Read DMA and Write DMA commands, all other commands must be performed using PIO. DMA or PIO data transfer mode selection by the host is performed on a command-by-command basis. Advanced Host Transfers ----------------------- The AC11600/23200/34300/35100 support high-speed Mode 3 and 4 PIO. These are data transfer modes that utilize hardware handshaking between the host and the drive via the IORDY signal. When the drive deasserts the IORDY signal, the host extends the read/write cycle until IORDY is asserted, thereby eliminating data corruption from overrun and underrun conditions. When in Mode 3 PIO, data can be transferred in bursts to and from the host at a rate of up to 11.1 MB per second; in Mode 4 PIO, the data can be transferred at a rate of up to 16.6 MB per second. Mode 3 and Mode 4 PIO are enabled on the drive by issuing a Set Features command. If Mode 3 or Mode 4 PIO is enabled, it can only be disabled by issuing another Set Features command, a hard reset, or by cycling power. To support Mode 4 PIO, Flow Control must be enabled in the host system. If this mode is enabled on a system that does not support Flow Control, host FIFO errors can occur. Mode 3 and Mode 4 PIO timings were defined to facilitate EIDE drive integration into VL and PCI local bus systems. Zoned Recording --------------- Zoned Recording is a mechanism for increasing the capacity of the drive by increasing the Bit-Per-Inch (BPI) density of data written on the longer outer tracks of the drive. Track capacity (number of sectors) is constant within groups of tracks or zones, and is increased when the tracks are sufficiently long to accommodate a significant number of additional sectors. This incremental increase in track capacity moving outward on the disk surface creates a series of concentric zones with different data densities. 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. WD Caviar drives monitor read error rate, start/stop count, spin-up retry count, drive calibration retry count, G-list entry count, and multi-zone error rate. The hard drive updates and stores these attributes 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. WESTERN DIGITAL Defect Management Utility ----------------------------------------- All Caviar EIDE drives are defect-free and low level formatted at the factory. After prolonged use, any drive, including Caviar, may develop defects. If you continue receiving data errors in any given file at the DOS level, you can use the defect management utility WDDIAG.EXE to recover, relocate and rewrite the user data to the nearest spare sector and maintain a secondary defect list. Caution: As with all format utilities, some options in the WDDIAG.EXE utility will overwrite user data. Dual Drive Option ----------------- WD Caviar drives support ATA-4 dual drive operations by means of configuratin options for master or slave designation. The WD Caviar is 100% ATA-4 compatible regarding the timing of the PDIAG- and DASP- signals. A jumper must be placed in the drive's option area for both master and slave configurations. If a jumper is placed in the drive's option area for both master and slave configurations. If a jumper is placed on the cable select (CSEL) option, the drive address selection will be determined by the CSEL signal on the drive cable. Connection to the host is implemented by means of a daisy-chain cable assembly. The SDH Register contains the master/slave select bit for the Caviar. The DASP- signal is a time-multiplexed indicator of Drive Active or Slave Present on the Caviar'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 command processing and released upon completion of the comand. If the master drive option has been configured, the WD Caviar will not respond to commands or drive option has been configured, the WD Caviar will not respond to commands or drive status on the interface when the slave bit is selected in the SDH Register. ********************************************************************** G E N E R A L ********************************************************************** WESTERN ENHANCED EIDE Enhanced IDE Backgrounder ========================= The Computer Market and the IDE Interface: ------------------------------------------ The computer marketplace is segmented into various classes of machines divided by user expectations in terms of cost, performance, compatibility and ease-of-use. The largest distinct segment today is the personal computer market, characterized by single- user products supporting a broad user base. The usage of these machines in business and home environments has dictated an emphasis on cost and compatibility. Historically, cost and compatibility in the personal computer marketplace have been more important to mainstream users than very high performance. The PC user has simply not been willing to bear the added cost or potential lack of compatibility that highest performance solutions imply. Given this criteria, the mainstream volume personal computer market has standardized on the IDE interface for its primary storage needs. The success of the IDE interface in the PC market has resulted primarily from a perfect match between IDE's offerings and the requirements of the market it serves. Specifically, its low cost of connection, compatibility, and ease-of-use, compared to alternative interfaces such as the Small Computer System Interface (SCSI), have been essential attributes in satisfying an expansive price-sensitive user group. In addition, because of the broad user base it serves, the personal computer market has traditionally required only hard disk support to meet its mass storage requirements. IDE has therefore evolved as a drive-only interface. Increasing Need for Performance and Connectivity Flexibility: ------------------------------------------------------------- As the personal computer market matures, it continues to display an increased emphasis on enhanced performance and connectivity capabilities, while maintaining its focus on cost, compatibility and ease-of-use. The market criteria has therefore grown to include higher performance attributes without sacrificing the needs of its price sensitive customers. It is in the realm of higher performance characteristics and connectivity that today's traditional IDE interface faces challenges. Other existing interfaces, such as SCSI, provide greater flexibility and performance options to meet these requirements, while failing to provide IDE's benefits of compatibility, cost and ease-of-use. Western Digital's Enhanced IDE technology addresses the performance and connectivity challenges facing the IDE interface. Enhanced IDE is designed to extend the attributes of the IDE interface so that its characteristics more effectively match the new requirements of the evolving personal computer market, without forfeiting its traditional benefits. Western Digital and the IDE Interface - Building upon Expertise: ---------------------------------------------------------------- Western Digital's Enhanced IDE technology evolves from the company's storage expertise within the personal computer marketplace. In 1984, Western Digital developed the WD1002 floppy and ST506 interface hard disk controller that IBM utilized in their PC/AT systems. The success of the PC/AT architecture led to the massive growth of the IBM PC/AT compatible market. This dramatic growth was in part fueled by WD1002 compatible hard disk controllers and later by Western Digital's standard-setting WD1003 series of AT controllers. As the market expanded and became more price sensitive, Western Digital defined the need for integration of the AT controller electronics within the disk drive. By working with Compaq Computer Corporation, Western Digital again drove the technology by proposing the IDE (Integrated Drive Electronics) interface which was implemented in the industry's first IDE drive in 1986. The disk drives used in personal computers have standardized around IDE since this introduction. ATAPI Specification: -------------------- Now, Western Digital continues to lead the industry with its IDE interface expertise via Enhanced IDE, an approach that expands upon the existing attributes of the IDE interface and extends its usage into more demanding environments. Enhanced IDE not only incorporates high speed host transfer capabilities, support of high capacity disk drives, and multiple device connectivity, but it also includes non-disk peripheral support via the Western Digital authored ATAPI (AT Attachment Packet Interface) specification. This enhanced IDE-ATA specification enables connectivity of non-disk peripherals such as CD-ROM and tape drives. The Western Digital defined ATAPI specification, with participation and endorsement by key market-making OEMS, CD-ROM suppliers and operating system suppliers, is yet another example of Western Digital's commitment to the evolution of the IDE interface. Enhanced IDE: ------------- Enhanced IDE removes many of the existing limitations and issues associated with the current IDE interface. Removal of these limitations enables IDE to grow with the industry's increased mass storage requirements without sacrificing its key cost, compatibility and ease-of- use attributes. The historical limitations of IDE relative to other interfaces, such as SCSI, have not threatened IDE's dominance of the PC marketplace to date. Upcoming personal computer systems, architected around high performance processors, more complex operating systems, and more demanding software applications, have developed storage requirements beyond the realm of today's IDE capabilities, challenging IDE's dominant role in the PC market. Specifically, the IDE interface is less flexible and limited in key areas of performance and connectivity relative to the SCSI interface: The IDE interface supports two disk drives. The SCSI interface supports multiple devices includingprinters, CD-ROM, tape drives as well as hard disk drives. The IDE interface is limited to 528MB hard disk capacity as a result of the Int 13h BIOS interface used to access IDE drives. The SCSI interface is not limited in capacity. The IDE interface typically offers 2-3MB/sec host transfer rates on standard ISA bus architected machines. The SCSI interface offers 10MB/sec FAST transfers and up to 20MB/sec FAST/WIDE host throughput. Western Digital's Enhanced IDE technology offers solutions to the existing constraints associated with the current IDE interface such as capacity limitations, slower host transfers, and connectivity issues associated with the IDE interface and thereby enables a cost effective, compatible, and easy-to-use interface solution for the next generation of personal computers. Components of Enhanced IDE: --------------------------- Enhanced IDE focuses on removing four primary limitations of the existing IDE interface. These include: Removal of the 528MB capacity barrier Breaking the IDE transfer bottleneck Supporting multiple IDE devices Enabling non-disk peripheral connectivity, such as CD-ROM Below, each of these limitations is discussed and resolved in detail. Removal of Capacity Limitations ------------------------------- A barrier in implementing IDE disk drives greater than 528MB exists in today's standard AT system BIOS. This barrier is based on historical reasons dating from the development of the original AT machine in 1984. Specifically, it is a limitation of the combined Interrupt 13 software interface and the IDE interface. The goal is to change the system BIOS such that this barrier no longer exists, thereby enabling the usage of high capacity IDE disk drives. Western Digitial's specification for removing the 528MB barrier is a simple yet effective method for implementation by BIOS suppliers and system manufactures who write their own BIOS. The capacity limitation exists due to the number of bits allocated for specifying the cylinder, head, and sector address information at both the Int 13h interface level and at the IDE interface level. Because Int 13h and IDE specify differing values, combining these two interfaces produces an artificial 528MB barrier as shown below: BIOS IDE --------------------------------------------------------------- Limitation Max Sectors/Track 63 225 63 Number of Heads 255 16 16 Number of Cylinders 1024 65536 1024 Maximum Capacity 8.4GB 136.9GB 528MB Two solutions exist that resolve the existing 528MB barrier problem. The first method is to have the BIOS translate the CHS address at the 13h interface to the CHS parameters being used at the drive interface. The Enhanced IDE proposal to break the 528MB barrier is to utilize the second method of modifying the Int 13h BIOS so that it translates the cylinder, head, sector information passed to it via Int 13 into a 28 bit Logical Block Address (LBA). The LBA solution is believed to be the best method of breaking the 528MB barrier because it provides a clean and efficient way for future operating system drivers to access IDE drives. The LBA translation is loaded into the drive's task file registers. Bit 6 of the drive's SDH register is set to indicate to the drive's firmware that it should interpret the information in its task file registers as LBA rather than cylinder, head and sector information. This scheme will allow for the full use of all of the bits allocated for CHS information at the Int 13h interface, thereby supporting up to 8.4GB. Using a logical block addressing scheme is attractive primarily because it is 100 percent compatible with BIOS Int 13 and allows for reduced overhead, producing higher performance. The logical block addressing scheme provides the compatibility essential for personal computer usage as well as enables the implementation of higher capacity disk drives required for high performance machines. Western Digital's LBA scheme has been successfully demonstrated by key system manufacturers writing their own BIOS and by those working in conjunction with their BIOS suppliers. Systems shipping in calendar Q4, 1993 will implement this scheme with the Western Digital Caviar AC2540. Bypassing the AT-IDE Host Transfer Bottleneck: ---------------------------------------------- The ISA bus capabilities are designed to sustain host throughput data rates of roughly 2-3MB/sec. Relative to SCSI host transfer rates of 5MB, 10MB, and 20MB/sec, the ISA bus is painfully slow for higher performance applications. Because AT personal computers did not necessarily demand the higher performance obtained by their workstation or file server counterparts, 2-3MB/sec wasn't considered a limiting factor. In addition, the ISA bus capabilities of 2-3MB/sec did not present a throughput problem because data rates coming off the media were roughly only 5Mbits/sec, and not a challenge to the host throughput. As disk drive areal density technologies progressed, media data rates began to exceed the 2-3MB/sec ISA host throughput. Buffering either on the system or the drive was necessary to maintain performance. The industry's most recent drive offerings far exceed the ISA bus host throughput by providing media data rates of up to 48Mbit/sec. Due to these factors, increased buffering is not a cost effective alternative to faster host throughput. Fast PIO Transfers: ------------------- Other peripherals within the computer, such as video, resolved their throughput problems via local bus architectures providing a potential path for improved performance. IDE local bus solutions, leveraged from the success of video local bus, began appearing in 1992, as a way to enhance data throughput. These solutions mapped the IDE data port to the local bus, bypassing the ISA bus and enabling the maximization of throughput from the media to the drive buffer, on to the host. These solutions were still not competitive with Fast SCSI (10MB/sec) due to the "blind" transfer nature of the PIO transfers. "Blind PIO" transfers indicate host control of data throughput with the host requesting data (master) and the drive responding (slave). With blind PIO transfers, the host is unaware or "blind" when buffered drive bandwidth is 100% available for host transfers. Because there are cases when only a percentage of bandwidth is available, blind PIO host requests for data from the drive are based on the worst case bandwidth availability. This means that even when the ISA bottleneck is bypassed by connection directly to the local bus, inability to utilize 100% drive bandwidth prevents full optimization of host throughput. Enhanced IDE incorporates an operation called "Flow Control Using IORDY" (I/O Channel Ready) which allows the drive to "throttle" the host when necessary and enable burst transfers to take advantage of 100% of the bandwidth. Flow Control thereby gives control of the data transfer to the drive and eliminates the inefficiencies of blind PIO by setting the host to maximum drive bandwidth support. This means that when 100% drive bandwidth is available, the drive will take control and transfer data to the host. This operation, based on approved Mode 3 PIO timings of 180ns cycle times from the Small Form Factor Committee, supports transfer rates up to 11MB/sec competitive with FAST SCSI solutions. Flow Control is enabled on the drive by the host issuing a Set Features command, so that both the host and drive side support this operation. Western Digital's 540MB drives (shipping beginning September, 1993) support flow control using IORDY and will be implemented into machines that take advantage of this feature via low cost ASICS whose functionality will later be incorporated into core logic chipset solutions. DMA Transfers -------------- Although PIO is the standard transfer method supported by the industry and presents no incompatibility issues (see footnote), another transfer option exists that provides incremental transfer benefits beyond PIO. Direct Memory Access (DMA) is based on data transfer directly to memory rather than via the CPU. DMA transfers are "throttled" and therefore have historically offered the benefit of maximizing data throughput. The throttling mechanism associated with DMA has historically enabled improved data transfers relative to standard PIO. Type B DMA was defined with the arrival of Extended Industry Standard Architecture (EISA), and is specified at 4.0MB/sec transfer rates offering an advantage to the standard 2-3MB/sec PIO data rates. Although this is an improvement to the standard ISA bus timings, Type B DMA remains uncompetitive with FAST SCSI timings of 10MB/sec. With the advent of local bus solutions, a new DMA transfer has emerged in conjuction with PCI. Type F DMA is defined to support 8.33MB/sec and 6.67MB/sec data rates, a large improvement over Type B DMA. In conjunction with chipsets capable of supporting 6.67MB and 8.33MB/sec data rates, the Small Form Factor Committee has approved a new multiword DMA Mode 1 timing specification of a 150ns cycle time. This enables DMA transfers up to 13MB/sec for future data rate improvement by allowing multiple words to be transferred for any given request command. PCI chip sets will be shipping with both EISA (Type B) and ISA (Type F) configurations in the calendar CYQ4'1993 time frame. PIO versus DMA: --------------- The disadvantage of DMA transfer operations is that the PC/AT hard disk controller and later IDE, evolved around PIO data transfers. Therefore, the system Int 13h BIOS and the embedded operating system device drivers have supported PIO transfers versus DMA transfers. This simply means that BIOS changes and external device drivers are necessary to achieve the incremental performance that DMA offers. Western Digital's Enhanced IDE program supports system manufacturers' choice of either PIO transfers via Flow control with IORDY for Mode 3 PIO data rates or DMA transfers (both Type B and Type F) via the development of external DMA device drivers supporting Western Digital hard disk drives. Product platforms based on both high speed transfer options will be in production in calendar fourth quarter 1993. Supporting Multiple IDE Devices: -------------------------------- The original IBM PC/AT defined support for two hard disk controllers and allowed support for up to four disk drives via a primary and secondary controller. The original BIOS and operating system drivers, however, only supported the primary controller, limiting the standard PC configuration to two disk drives. Today's operating systems now offer both primary and secondary controller support providing an opportunity to extend peripheral attachment capabilities with IDE. The addition of a second connector via a hardware change is a simple, low cost solution that allows for multiple IDE peripheral connectivity. The cost of a second IDE connector is less than $1.00. Most core logic and Super I/O devices have already integrated the capability to support either the primary or secondary address decode logic and therefore the cost of the secondary port is simply the 40 pin connector and surrounding transceivers and resistors. For $1.00, dual IDE connectors offer support for four IDE devices and satisfy the expansion needs of the majority of the mainstream personal computer market, a very cost effective alternative to connectivity via SCSI. Western Digital's Enhanced IDE program works with system manufacturers to understand the BIOS implications of a secondary channel for support of two additional IDE devices. The BIOS must be able to determine the physical location of the drive based on the Int 13h drive number . Since DOS 3.0 and later will support up to seven disk drives, only the system BIOS Interrupt 13h needs to be modified to support primary and secondary IDE. Windows 3.1 accesses the disk via Interrupt 13h calls to the BIOS. Again, all that is required is modification to the system BIOS to support dual channel IDE. IBM OS/2 2.0 and 2.1 as well as MS/IBM OS/2 1.31 all support four IDE drives on dual IDE connectors via their drivers. Netware is hardcoded to support four IDE connectors or 8 IDE devices. Dual channel IDE support will be in the final release of Windows NT. Dual channel IDE not only enables the cost effective and easy implementation to support multiple disk drives, it presents the opportunity to expand IDE into non-disk peripheral support. A slow speed channel and a high speed channel can be developed for efficient implementation of storage solutions via high performance hard disk drives and mass data storage vehicles such as CD-ROM and tape drives. Enabling Non-disk Peripheral Connectivity: ------------------------------------------ The upcoming high performance desktop machines are demanding additional storage peripheral support beyond hard disk drives. Specifically, CD-ROM and tape drives will demonstrate rapid unit growth rates as these peripherals become a more standard part of the desktop's configuration. Today's CD- ROMs and tape drives have multiple interfaces that present compatibility and performance issues. Development of a standard IDE interface for both CD-ROMs and tape drives solves cost, compatibility, performance, and ease-of-use issues in conjunction with enabling the attachment of non-disk devices via the IDE interface. Western Digital, with its AT interface expertise, has taken the leadership position in expanding the IDE interface to support non-disk peripherals by authoring the AT Attachment Packet Interface (ATAPI). The specification defines a standard method for interfacing to a CD-ROM drive (and other non-disk devices) utilizing the existing ATA host computer hardware and cabling. ATAPI supplements the definitions of an ATA mass storage peripheral found in the ATA specification and is compatible with existing ATA hardware without any changes or additional pins. Traditional computer architecture has used a register based transport mechanism. Modern architectures now use packet-based transport mechanisms. ATAPI is an enhancement to IDE that follows this trend. Benefits of including a packet-based scheme means adding very few IDE operation codes. The ATAPI specification adds only a single new IDE command to obtain functionality and only two additional new IDE commands to address compatibility. Once a packet-based interface was defined, the next issue was deciding what command packets definitions to utilize. Given widespread support for SCSI within peripherals and within existing operating systems, it was decided to derive ATAPI command packets from SCSI to minimize development time and expense. The ATAPI specification is being reviewed by an industry working group that consists of market-making system manufacturers, CD-ROM suppliers, silicon designers, BIOS developers, and Western Digital. The objective is to finalize the ATAPI specification around which these companies will design and manufacture products for the personal computer industry. Although the exact strategy has yet to be decided upon, the document will eventually be submitted to a standards committee for adoption. Putting it All Together ------------------------ Support for four IDE devices Fast IDE port for disk drives Slow IDE port for CD-ROMs and tape True plug and play Lowest cost of connection Overlapped I/Os for higher performance The Big Picture: ---------------- It is clear that the mass storage needs of the personal computer industry are expanding to include higher performance and connectivity requirements. Enhanced IDE was developed in response to these requirements. The industry is already embracing Enhanced IDE and its elements of improved functionality, performance, and connectivity by introducing products in the calendar fourth quarter of 1993. These products include BIOS support for >528MB IDE hard disk drives, the shipment of >528MB IDE drives themselves, silicon and controller products supporting fast PIO and DMA transfers, and hardware supporting dual channel IDE for multiple device connectivity. Momentum in the development of the industry's first standard IDE non- disk peripherals is well underway with the industry's first IDE CD-ROMs anticipated to ship in calendar first quarter 1994. SCSI and IDE Scorecard: The industry activity backed by real Enhanced IDE products means that IDE has met the challenge in addressing the industry's new requirements. IDE's cost effectiveness and compatibility advantages, matched now with high performance and connectivity attributes make it a solid storage interface solution well into the future. A new comparison of the AT/SCSI scorecard reveals the successful approach of Enhanced IDE: Standard AT Interface -------------------- * The IDE interface supports two disk drives. * IDE is a hard disk only interface. * The IDE interface is limited to 528MB hard disk capacity as as result of the Int 13h BIOS interface used to access IDE drives. * The IDE interface is typically limited to 2-3MB/sec host throughput. With Enhanced IDE ----------------- * The IDE interface supports four IDE devices with dual channel IDE and more with multiple IDE connectors. * The IDE interface supports non-disk peripherals such as IDE CD-ROM, IDE Tape. * With LBA, the IDE interface supports up to 8.4G of hard disk capacity. * With Mode 3 PIO and multiword DMA mode 1, data transfer rates with IDE drives can be from 11MB/sec up to 13MB/sec. With Enhanced IDE, the IDE interface has become a mass storage interface for personal computers and is no longer simply a disk drive interface. Enhanced IDE complements SCSI in that it remains primarily an internal interface solution with SCSI as an external interface solution. Western Digital is a registered trademark of Western Digital Corporation. All marks mentioned herein belong to other companies. PIO transfers are based on using the CPU to perform the data transfer (Processor I/O) and is the standard transfer method supported within all existing BIOS and all embedded operating system device drivers. PIO implies compatibility with existing BIOS/OS and therefore does not require added device driver support for operation.