[Products] Large Disk Integration The extensive growth in the Personal Computer marketplace, coupled with the popularity of applications such as multimedia, gaming, and the downloading of information from on-line have caused a great demand for larger and larger disk drives. In order to build up the existing industry-standard IDE interface to allow for faster, higher capacity drives, Western Digital, along with other key industry players, led the effort to strengthen the existing IDE interface in 1993. The new interface, called Enhanced IDE (EIDE) removed the four primary limitations of the existing IDE interface. These were the 528MB capacity barrier; the IDE transfer bottleneck (faster disks); support for up to four IDE devices; and enabling non-disk peripheral connectivity (such as ATAPI CD-ROMs). A New Era of Computing: The original capacity limitation of 528MB was due to the number of bits allocated for specifying the cylinder, head, and sector address information at both the Interrupt 13h interface level and at the IDE interface level. This barrier was surpassed with the implementation of EIDE by either a software "fix" which was shipped with retail upgrade kits by Western Digital and other leading drive manufacturers, or the addition of a controller card, or a BIOS (Basic Input Output System) upgrade. As the industry crossed the 1024 cylinder level with the first "barrier-breaking" drive (drives over 528MB in capacity), BIOS developers were facing yet another barrier at the 4095 cylinder limit. The solution for the 1024 barrier was the translating BIOS. However, with some implementations of a translating BIOS, a BIOS limitation occurs -- limiting the maximum cylinders accessible by the BIOS to 4095, or 2,113,413 bytes (4095 cylinders, 16 heads, 63 sectors, 512 bytes), or drives over 2.1GB. BIOS Limitation: Depending on the exact method used by BIOS developers to implement the translating BIOS, the BIOS limitation reacts in a number of ways on drives larger than 4095 cylinders (over 2.1GB). Distinct reactions exist with individual BIOS s from each BIOS manufacturer. Because of the variety of BIOS manufacturers, the number of BIOS upgrades, and the differing timelines of OEM implementation of BIOS upgrades within system configurations, it is difficult to predict system reactions for a specific PC. Western Digital's research has shown that many BIOS's dated from approximately 1992 to February, 1996 will cause the PC to experience a BIOS limitation upon drive installation. These PCs will require a system limitation fix to achieve full benefit of the large drive capacity. The following chart is an estimated percentage of systems affected by the BIOS limitation. These figures are based on BIOS's shipped from approximately 1992 through February, 1996 by major BIOS manufacturers. 528MB or less Truncate 5% BIOS's 92-96 Lock-up 47% BIOS's 92-96 Truncate 28% New OK systems Access full capacity 5% Unknown (misc. PC clones) ? 15% The following reactions are seen when combining a large drive with more than 4095 cylinders and a BIOS containing a limitation that cannot support larger disks. Note: BIOS manufacturers have made the required changes to their products, and new systems moving forward should not experience the BIOS limitation. BIOS Limitation Scenarios: * The BIOS can view only a maximum of 2.113 GB or 4095 cylinders and truncates, or shortens, the remaining space. In the case of a 2.5GB drive, the end user will not be able to derive the full benefit of a driveÆs capacity, missing approximately 400MB of capacity. * The BIOS shortens the number of cylinders at 12 bits, limiting the drive capacity to approximately 400MB, and losing 2.1GB. * At boot time, the BIOS will cause a system lock-up, making the entire system inaccessible. BIOS Limitation Solutions: There are numerous ways to get past the BIOS limitation in order to utilize the full capacity of the drive, as well as any other situation caused by the translating BIOS. Continuing Western Digital's commitment to provide the easiest and most complete solutions to the market, each method is detailed below. Western Digital recommends that users revise the CMOS set-up and install the software utility. However, should this solution not work with an individual PC, Western Digital has included an additional solution, which includes the use of one more jumper, so that all users should be able to gain full use of a drive. An extra jumper is shipped with all Western Digital Caviar retail kits and distribution sales for this specific purpose. 1. Flash BIOS Upgrade If a system contains a flash BIOS, or user programmable BIOS chip, it is possible to upgrade the system with a newer BIOS version that corrects the limitation using the manufacturer's provided flash utilities and BIOS update images. The new BIOS could correct the limitation that causes the lock-up or truncation (space shortening) situation so that full use of a 2.5GB drive would be possible. To find out what type of BIOS is in an individual system, the user should contact their system manufacturer. This solution requires no additional software. Users may gain additional BIOS features with the upgrade (such as bootable CD-ROM, Plug and Play features), without added cost. However, this scenario requires some expert knowledge to run the flash utility, and errors made during flash programming can render a system unusable. As with the Flash BIOS, some vendors may not have flash BIOS upgrades available. This is a difficult task to undertake, and if not offered free of charge, can cost upwards of $35. 2. Non-flash BIOS (ROM BIOS) Upgrade: This solution is identical to the above with the exception that the system does not support end user reprogrammable features of the BIOS. The user is required to obtain an upgrade ROM chip for the system, remove the existing BIOS and install the upgrade ROM. This new BIOS would have the ability to support drives 2.5GB or larger. To determine the type of BIOS in an individual system, users should contact the system manufacturer. As with the above, this solution requires no additional software, and the user may gain additional BIOS features with the upgrade. This solution also requires expert knowledge, and may cause system damage if done incorrectly. As with the above, not all vendors may have ROM BIOS chip upgrades available, and an additional cost may be incurred. 3. Software Add-on: In situations where the BIOS causes a truncation or shortening of drive capacity, causing a loss of approximately 400MB, or a wrap around BIOS-caused loss of 2.1GB, a software utility can be used to access full drive capacity. With the software solution, the drive automatically supports full capacity in systems with the BIOS limitation, and no additional hardware tools are required. To gain full drive capacity, the user needs to go through the following steps: - Install drive - Boot drive - After boot, the drive will not be able to access full capacity - Install software, the EZ-Drive software from Micro House International will make the remaining space available on the drive Note: This solution alone will not work in the case of a system lock-up as the system will lock-up prior to the boot process. If the system supports user definable drive type, the user may choose to configure the device for less than 4095 cylinders prior to drive installation. Once the drive is installed, the user may then use the EZ-Drive software to access the full drive capacity. To do this, the user simply selects the user definable drive type option in the BIOS, enters 4092 (to revert the system to configure the drive at 2.1GB) for the number of cylinders on the drive, and then proceed to install EZ-Drive. EZ-Drive is provided free-of-charge by Western Digital with the Caviar AC32500, 2.5GB drive. The use of the software utility does require that a user enter the BIOS set-up and configure a drive manually. This may cause some difficulties if the user does not have the system manual. If the system is not user definable, the set-up program cannot be entered, and the drive cannot be installed without a BIOS upgrade or use of the extra jumper. Western Digital Recommendations: In order to provide the best possible solution for BIOS limitations, Western Digital has opted to ship the Caviar AC32500 with the EZ-Drive software utility, and an additional jumper (which is to be used if a system does not support user-definable drive types). With any implementation of these solutions, a BIOS upgrade is not necessary. CMOS Set-up Revision and Software Utility: Most systems can be reconfigured to gain full access of a 2.5GB drive with a simple CMOS revision and use of the software utility. Systems generally provide a CMOS set-up program that accesses information on system configuration. Users should check their systems manuals for further information on CMOS set-up. Drive types generally offered in CMOS include auto config, user defined and predefined. Selecting the auto config drive type automatically sets up the Western Digital hard drive parameters. This drive type is used for DOS, Windows 3.1x, Windows NT, Windows 95, OS/2 2.1x and OS/2 Warp. Resetting the system configuration for auto config, coupled with the installation of EZ-Drive should provide full access to the complete 2.5GB drive capacity. System BIOS Doesn't Support Drives With Over 4095 Cylinders: If a system BIOS does not support drives with over 4095 cylinders, there are a number of solutions available. When a system locks up before CMOS can be entered, a user can simply turn off the system, and disconnect the IDE cable from the system in order to access CMOS set-up. This will enable the user to then select user defined drive type, enter 1023x16x63, and reconnect the IDE cable to the system. Combined, these procedures will allow the user to reboot the system without locking up, and install EZ-Drive. Additional Jumper Usage: Systems that do not support the user-definable drive types require one additional step during the installation process to get to the 2.5GB capacity point. These systems can overcome the BIOS limitation by either a BIOS upgrade or may use a special jumper setting to access the drive. A special jumper setting will trick the system and limit the drive at boot time to 4092 cylinders (2.1GB), so that the BIOS will not cause a system lock-up. Once the system has booted, the user can install EZ-Drive, which will recognize the special configuration and jumper setting on Western Digital drives. EZ-Drive will then query the drive for true capacity, and set the drive system parameters to the 2.5GB capacity point. Note: Drives configured with the additional jumper will always need to be used with the second jumper in order to read data. As the PC market continues to grow as a mass consumer market, Western Digital continues to strive to present full and complete storage solutions to the consumer. Western Digital is the only drive company to currently provide the EZ-Drive software utility and additional jumper to its customers to ensure the easiest transition through the BIOS limitation, and achieve full use of large EIDE disk drives. Western Digital's charter is to educate the consumer, and make the computing experience a less frustrating one. --------------------------------------------------------------------------- [ ] [ Home | New | Company | Products | Where2Buy | Service | Coolstuff | Promos | Partners | Employment | Index | Search ] Many Western Digital documents are available in Acrobat format. ©Copyright 1994, 1995, 1996 Western Digital Corporation. All rights reserved. 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