PRE-INSTALLATION NOTES FOR MICROSOFT WINDOWS NT VERSION 3.51 Install Windows NT from CD-ROM or floppy disks as described in Chapter 1 of the Installation Guide. This file contains additional information you may need prior to installing Windows NT on some hardware configurations CONTENTS========================================= Additional Installation Information Hardware Compatibility List Updates Using PCMCIA Devices with Windows NT 3.51 Licensing Information Licensing Logging Service Server Setup and Licensing Installing Windows NT Workstation 3.51 from Windows 95 ...Installing Windows NT Workstation 3.51 Using Floppy Disks ...Installing Windows NT Workstation 3.51 Using a CD-ROM and 3.5 Inch Setup Disks ...Installing Windows NT 3.51 from a Network Distribution Share Installing over the Network Without Floppy Disks Dual Booting Windows NT 3.51 with Windows NT 3.x Using Floppyless Setup when a 3rd Party Driver is Required to Access the Boot Partition Boot Floppy Disks Creating Backup Disks Upgrading Windows NT 3.5 to Windows NT Server 3.51 Upgrading Bookmarks in Help files Upgrading When Third-Party System Software is Present Using Eicon X.25 Software with Windows NT 3.51 Locating Third Party Network Card Drivers Setting Up Windows NT 3.51 on Computers with Multiple CD-ROM Drives Installed CD-ROM Installations Require Local CD-ROM Drive Running Windows NT 3.5 on PCI Bus Systems Update Required when Retaining Windows NT 3.1 Installation Directory Installing to Mirrored Partitions Selecting Keyboard Layout NextStep Changes to Partition Tables Disk Fragmentation Can Prevent Installation MS-DOS Undelete Sentry Blocks Using MS-DOS Based Disk Utilities Interrupt Conflicts ROM Shadowing on Multiprocessor Systems SCSI Devices Must Be On for Setup Disconnect UPS Serial Connections ACER AcerFrame 3000 MP Using the On Track Disk Manager Utility Boot Disk with Windows NT 3.51 Using DriveSpace or DoubleSpace on Windows NT 3.51 Digital Alpha AXP Firmware Must Be Upgraded Digital Venturis Systems with S3 Based Video Gateway Nomad and TI Travelmate Notebooks Installing Windows NT 3.51 on an IBM Personal Computer Power Series IBM Personal System/2 IBM ThinkPad Intel EtherExpress 16 LAN Adapter Toshiba T4400SX Monochrome Caching Disk Controllers and Drives Installing Windows NT on an ESDI Disk Drive with More Than 1024 Cylinders ================================================= Additional Installation Information ----------------------------------- For general hardware information, see Chapter 2, "Troubleshooting," in the Installation Guide. This chapter contains general troubleshooting information about interrupt conflicts, unsupported peripherals, network adapter cards, SCSI drives, and video display adapters. See the Windows NT Hardware Compatibility List to determine which hardware components have been tested by Microsoft for compatibility with Windows NT. After you install Windows NT, read the following three text files: README.WRI contains general information about Windows NT, including information on specific hardware and software. PRINTER.WRI contains information about specific printer problems or components. NETWORK.WRI contains information about networks, including information on network adapter cards and network interoperability. Hardware Compatibility List Updates ----------------------------------- Please check for updates of the Hardware Compatibility List for Windows NT version 3.51 on the following electronic services locations: Compuserve WINNT forum, Library 1 MSWIN32 forum, Library 17 Internet ftp.microsoft.com cd\bussys\winnt\winnt-docs\hcl\hcl351d Using PCMCIA Devices with Windows NT 3.51 ----------------------------------------- When using PCMCIA devices, such as modems and network cards, on a Windows NT Workstation, power management features on the computer system should be turned off. Consult the manufacturer's system manual for procedures to disable power management. Licensing Information --------------------- You can license your Windows NT Server computer in either per seat or per server mode. The Licensing Logging Service provides the administrator with information that will help manage and track licenses. For more information on per seat and per server licensing, please refer to the Windows NT Update Information for Version 3.51 book. Licensing Logging Service ------------------------- Once you have chosen the per server option, you must enter the number of Client Access Licenses you have purchased to be used with this server. Each Client Access License provides an additional concurrent connection. For the beta, you can designate the server for use with up to 100 concurrent connections. During setup, you will be required to designate a licensing option for your server either per seat or per server, as described below. If you choose the per server option, there is a one-time conversion opportunity per seat. There is no conversion opportunity for per seat server. For more information on per seat and per server licenses, please refer to the book Windows NT Update Information for Version 3.51. Server Setup and Licensing -------------------------- During Windows NT Server Setup, the user is asked to accept a Legal Licensing Agreement. The user must be present to accept the agreement. It is possible to run Setup without being present if you include an unattended script on the command line, such as Winnt32 /u MyScript. For more information, see the UNATTENDED.TXT file on the Microsoft Windows NT Resource Kit Version 3.5. Installing Windows NT Workstation 3.51 from Windows 95 ------------------------------------------------------ You can install Windows NT Workstation 3.51 from a computer that is already running Microsoft Windows 95. This enables you to start the computer using either operating system. There are three ways that you can install Windows NT Workstation 3.51 from Windows 95. You can use 3.5" Setup disks, a CD-ROM and 3.5" Setup disks, or you can install Windows NT Workstation from the network. Installing Windows NT Workstation 3.51 Using Floppy Disks Because Windows NT 3.51 Setup only supports 3.5 inch Setup floppies, your system must have a 3.5" A drive in order to install using floppies. To install the Windows NT Workstation 3.51, you must have three blank, formatted, high density 3.51" floppy disks, and an additional disk to format during setup. Re-start your computer and boot from the first Windows NT Setup Boot Disk and follow the instructions on your screen. Setup will allow you to install Windows NT Workstation 3.51 into a new directory, and will ensure that you can choose to boot either Windows 95 or Windows NT when the computer starts. Installing Windows NT 3.51 Using a CD ROM and 3.5 Inch Setup Disks If you have a Windows NT CD-ROM and three 3.5 inch Setup Disks, then you can install Windows NT 3.51 from your CD-ROM. Re-start your computer and boot from the first Windows NT Setup Boot Disk and follow the instructions on your screen. If the CD-ROM drive on your system drive on your system is detectable by Windows NT, and is working properly, Setup will detect it and install Windows NT 3.51 from the CD. Otherwise, you will be asked to provide the remaining 3.5" Setup boot disks. Setup will allow you to install into a new directory, and will ensure that you can choose to boot either Windows 95 or Windows NT when the computer starts. Installing Windows NT 3.51 from a Network Distribution Share You can install Windows NT 3.51 from a network distribution share. There are four different options for installing from a network share. 1. Install from a network distribution share and have Setup create the three 3.5 inch Setup Boot disks necessary to complete NT Setup. 2. Install from a network distribution share and have Setup copy the Setup boot files onto the user's local hard disk 3. Install from a CD-ROM drive by having Setup first create the three-3.5 inch Setup boot disk necessary to complete NT Setup. 4. Install from a CD-ROM drive and have Setup copy the Setup boot files onto the user's local hard disk. NOTE To install Windows NT 3.51 from Windows 95 and have Setup create the Setup boot floppies, type: winnt /w To install Windows NT 3.51 from Windows 95 and have Setup copy the Setup boot files to the local hard disk, type: winnt /b /w Installing over the Network Without Floppy Disks ------------------------------------------------ If you are upgrading or installing Windows NT from a share on your network, you can start WINNT.EXE or WINNT32.EXE with the /b switch and you will not need to use floppy disks during the process. You must have 4 MB of free hard disk space in addition to the minimum required for Windows NT files. To use this switch, the device your computer boots from must also be supported by Windows NT without requiring drivers from the equipment manufacturer. Most boot devices are supported by Windows NT without needing additional drivers. Microsoft suggests that when the Setup program offers to create boot floppies you accept the offer because these floppies are required when using the Repair disk to repair a Windows NT installation. Dual Booting Windows NT 3.51 with Windows NT 3.x ------------------------------------------------ The Windows NT File System (NTFS) in Windows NT 3.51 supports file-level compression. Versions of Windows NT that are earlier than version 3.51 do not support compression, and will not read compressed files, or directories marked for compression. Do not compress the files installed for Windows NT versions earlier than 3.51. If you have compressed these files, start Windows NT version 3.51, and then decompress all of the files and directories needed to start the earlier version. Using Floppyless Setup when a 3rd Party Driver is Required to Access the Boot Partition ------------------------------------------------------------- If you would like to use floppyless setup and your system requires a 3rd party driver in order to access the boot partition, you will need to supply the necessary OEM SCSI driver as your computer boots into the textmode portion of setup. To execute a floppyless setup: 1. When setup begins to load, the screen will turn from black with the text, "Setup is inspecting your computer's hardware configuration..." displayed at the top to blue with the text, "Windows NT Setup" displayed at the top. At this time, press the 'F6' key. You have two seconds in which to press this key. 2. Later in the load process, you will be asked to specify a SCSI driver, at which point you should supply the OEM SCSI diskette. Boot Floppy Disks ----------------- The boot floppy disks supplied with the CD-ROM version are identical to those used for a floppy disk installation of Windows NT. Creating Backup Disks --------------------- If you are a registered user and are having difficulty in creating a backup copy of the installation disks, contact your local subsidiary or Inside Sales regarding fulfillment disks. Disks formatted with DMF (Setup Disk 4 and beyond) can not be copied to a standard high density 3.5" disk using the MS-DOS DISKCOPY or Windows COPY command. Because DMF is a new format, many existing disk utilities such as Norton Disk Doctor, Central Point's PC Tools, and Microsoft's ScanDisk do not recognize DMF and may try to write over the file on the installation disks. Therefore, you should NOT attempt to use disk utilities to diagnose DMF- formatted disks. Upgrading Windows NT 3.5 to Windows NT Server 3.51 -------------------------------------------------- You can upgrade Windows NT 3.5 systems to Windows NT 3.51 Server. You cannot upgrade the computer to be a primary or backup domain controller. You can only upgrade the computer to be a server that does not participate in validating users. Upgrading Bookmarks in Help Files --------------------------------- When upgrading to Windows NT 3.51, you lose your bookmarks. To preserve bookmarks, type the following commands at a command prompt (cmd.exe): cd%SystemRoot REM navigate to your windows system root directory copy winhelp.bmk copy winhelp.bmk winhlp32.bmk REM make a copy of the file WINHELP.BMK, name it WINHLP32.BMK Upgrading When Third-Party System Software is Present ----------------------------------------------------- If you are using third-party system software that installs its own services, such as network redirectors, contact the software vendor to determine if any of these services should be disabled before upgrading. Using Eicon X.25 Software with Windows NT 3.51 ---------------------------------------------- If you are using Windows NT 3.5 with the Eicon X.25 software, you must obtain the latest Eicon X.25 update from Eicon Technology Corporation before upgrading to Windows NT 3.51. Eicon Technology Customer Service can be reached by calling (514) 631-5246, from 8:30AM to 6PM Eastern Standard Time To reach the Eicon Technology fax line, call: (514) 631-1006, 24 hours a day, 7 days a week NOTE: Outside of North America, contact your distributor for help. If you are a CompuServe member, type: go eicon Locating Third Party Network Card Drivers ----------------------------------------- Instructions for locating third party network card drivers can be found in the Hardware Compatibility List that is included in the Windows NT 3.51 retail box. Setting Up Windows NT 3.51 on Computers with Multiple CD-ROM Drives Installed ----------------------------------------------------- The Windows NT 3.51 Setup program goes through two processes when choosing the CD-ROM drive from which Windows NT 3.51 will be set up. First, when Setup is in text mode, Windows NT 3.51 prompts you to choose SCSI drives on your machine and will load Windows NT 3.51 from the first drive that was chosen. Second, when Setup is in GUI mode, Windows NT 3.51 accesses the CD-ROM drive depending on the priority that the CD-ROM drive has in the Windows NT Registry. This situation might cause the following error message to be displayed: "Please insert Windows NT Workstation/Server diskette #9 (or any other #) or Windows NT Workstation/Server CD-ROM." To set up Windows NT 3.51 on computers with multiple CD-ROM drives installed, choose the CD-ROM drive that has first priority. You will not be able to view which CD-ROM drive has priority on your computer, but you can follow this list: Non-SCSI devices in the following order: Sony®, Panasonic®, Mitsumi. IDE (ATAPI) devices SCSI devices -Or- You can place the Windows NT 3.51 CD in each CD-ROM drive until the CD-ROM drive that has priority on your computer accepts it for file copying. CD-ROM Installations Require Local CD-ROM Drive ----------------------------------------------- Installation from CD-ROM requires a supported SCSI CD-ROM drive physically attached to your computer. Please consult the Hardware Compatibility List for supported CD-ROM drives. Running Windows NT 3.51 on PCI Bus Systems ------------------------------------------ To run Windows NT 3.51 on a PCI bus system, it may be necessary to enable the interrupts either via the CMOS screen or by switching jumpers on the motherboard. Refer to system documentation to find out how to enable interrupts for your system. Update Required when Retaining Windows NT 3.5 --------------------------------------------- Caution: If you are installing Windows NT 3.51 and also keeping a copy of Windows NT 3.5 on the same computer, you must run UDPATE.EXE if you want to prevent damage to FAT partitions and to ensure that any version of Windows NT 3.5 installed on your computer can still access files on your NTFS partitions. If you do not run UPDATE.EXE, then after Setup is complete, the files on NTFS partitions cannot be seen by Windows NT 3.5. Also, using long filenames on FAT partitions might render those partitions inaccessible from within Windows NT 3.5. You do not need to run UPDATE.EXE if you are upgrading or reinstalling this new version and do not want to keep the older version of Windows NT on your computer. To update your Windows NT 3.5 system with UPDATE.EXE 1. Before running the Windows NT 3.51 Setup program, switch to the \FS31UPD\system_type directory on the Windows NT 3.51 CD-ROM. For example, you might switch to E:\FS31UPD\I386 for x86-based systems. - Or - For x86-based computers only, insert the Microsoft Windows NT 3.51 Update Disk in drive A and make that the active drive. 2. Run UPDATE.EXE. Follow the directions on the screen to complete the update. Installation Directory ---------------------- You should not install Windows NT 3.51 in the directory that contains Windows NT 3.5 unless you are upgrading. That is, Windows NT Setup might indicate that it has found a version of Windows NT on C:\WINNT, for example, and offer to upgrade the old installation. If you answer No to upgrading, then do not select this same directory (C:\WINNT) for installing version 3.51. Installing to Mirrored Partitions --------------------------------- Setup cannot write to partitions that are part of a fault-tolerant configuration. Therefore, it is necessary to break the mirror of a fault-tolerant set before installing to or upgrading an existing installation on that partition. Additionally, Setup must be able to write to the system partition, so it is necessary to break the mirror of system partitions that are configured as fault- tolerant sets. Since Setup treats fault-tolerant sets as though they have no free space, you will receive a "not enough space" error if you attempt an installation on a fault-tolerant partition. If you encounter such a message, and you are sure that you have enough space, check to see if your system partition and/or installation partition are fault- tolerant sets. If either or both partitions are mirrored, then break the mirror(s), and attempt the installation again. Using a LMHOSTS file -------------------- When Windows NT Workstation 3.51 or Windows NT Server 3.51 is installed, sample LMHOSTS.SAM and HOSTS.SAM files are located in the \systemroot\SYSTEM32\DRIVERS\ETC directory on the computer. The LMHOSTS.SAM file contains additional information about creating and using a LMHOSTS file. If you upgraded to Windows NT 3.51, your existing LMHOSTS files were not changed. If you performed a new installation of Windows NT, create a LMHOSTS file using Notepad or any other text editor. Be sure to add entries to the newly created LMHOSTS file based on the information in the sample LMHOSTS.SAM file. Selecting Keyboard Layout ------------------------- Be sure that usernames and passwords that are set for all users on a system are available on the default keyboard layout chosen for that system at setup time because there is no way to change keyboards at the logon screen. If you have selected a keyboard that does not include characters used in your username and password, and if you have the screen saver on with the lock option, then if you leave the system idle and the lock option is activated, you have no way of inputting your username and password without knowing the ALT+NUMPAD codes for the characters making it up. NextStep Changes to Partition Tables ------------------------------------ NextStep makes unconventional changes to partition tables. These changes can distort measurement of the amount of space remaining on a drive. If more space is reported than is actually available, installation can fail because of the lack of space on the drive. Disk Fragmentation Can Prevent Installation ------------------------------------------- If your disk is too fragmented, there may not be enough room for Windows NT Setup to create essential system files. If this occurs, Setup will not be able to convert a volume at the conclusion of installation. Before trying to convert the volume again, either delete some files, or back up and reformat the drive. MS-DOS Undelete Sentry Blocks ----------------------------- Windows NT cannot recognize free space that was created on a FAT partition using the undelete sentry feature in MS-DOS version 6.2. With the sentry method, MS-DOS reserves part of the hard drive to remember deleted files, then compensates during MS-DOS queries about free space. Because Windows NT doesn't understand sentry, it reports the space on the FAT partition as used. Using MS-DOS Based Disk Utilities --------------------------------- The new long filename format introduced in Windows NT 3.5 uses file elements on FAT partitions differently than MS-DOS. Using MS-DOS-based disk utilities on FAT partitions used by Windows NT 3.5 can cause files to be deleted or long filenames to be lost. Microsoft recommends that you run only disk utilities specifically designed for Windows NT 3.5 or, when running MS-DOS, the chkdsk or scandisk utilities. To prevent the Windows NT 3.5 FAT file system from using long names, you must set to 1 the following Registry entry: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet \Control\FileSystem\Win31FileSystem After changing the entry, you must restart your computer for the change to take effect. Caution: PCTools' diskfix utility is known to delete all files on the FAT partition. If you use MS-DOS-based disk utilities on a FAT disk partition used by Windows NT 3.5, the utility may cause the loss of long filenames or delete files on the FAT partition unless this Registry entry is set to 1. You should back up the FAT partition before running any disk utility other than chkdsk. Interrupt Conflicts ------------------- A common problem in a computer with several supported devices is conflicting interrupts, I/O ports, or memory usage. Where possible, we have identified such cases in this document. However, if one of the supported devices does not seem to work, it may be due to the particular hardware configuration. For more specific information, see your hardware manual or contact your system manufacturer. ROM Shadowing on Multiprocessor Systems --------------------------------------- If you encounter persistent installation problems on multiprocessor systems, try installing with ROM shadowing disabled. SCSI Devices Must Be On for Setup --------------------------------- You should ensure all SCSI devices are on prior to installing or upgrading Windows NT version 3.51. Disconnect UPS Serial Connections --------------------------------- UPS serial-monitoring cable connections should be disconnected during Setup. Windows NT attempts to automatically detect devices connected to serial ports, which could cause problems with UPS equipment connected to a serial port. ACER AcerFrame 3000 MP ---------------------- Before installing Windows NT, disable shadow RAM Video BIOS. Using the On Track Disk Manager Utility Boot Disk with Windows NT 3.51 ------------------------------------------------------ When you buy an IDE hard drive that holds more than 528 million bytes (504 megabytes), it comes with a disk called On Track Disk Manager. Disk Manager installs a custom boot sector on the drive that allows MS-DOS to see the drive's full capacity. The On Track Disk Manager is not supported by Windows NT and will keep Windows NT versions 3.1 and 3.5 from starting. Windows NT 3.51 is compatible with Disk Manager's boot sector program. Seagate® hard drives come with a disk manager called Microhouse EZ Drive, which was not supported on Windows NT 3.5 and is not supported on Windows NT 3.51. Using DriveSpace or DoubleSpace on Windows NT 3.51 -------------------------------------------------- If you compress files using the Microsoft DriveSpace or Microsoft DoubleSpace® disc compression utility on Windows 95 or MS-DOS, you will not be able to access the files using Windows NT 3.51. To avoid this situation, do not compress files using these utilities. Digital Alpha AXP Firmware Must Be Upgraded ------------------------------------------- Before installing Microsoft Windows NT Workstation or Windows NT Server 3.51 on a Digital Alpha system, you must verify that the required firmware revision is installed on your system. If the required version is not installed, you must upgrade your system's firmware to the latest version. Read the README.TXT file provided in the following locations to understand the firmware revisions needed for your specific Digital Alpha system. This document also provides specific instructions for obtaining and applying the firmware update. The README.TXT file is available in the following locations: * On CompuServe, in the DEC4WNT forum in the Library Section [4], Hardware Support. * Via FTP on GATEKEEPER.DEC.COM. Once connected to the gatekeeper, the README.TXT file can be found in /private/fwaxp. If you are still unsure about your particular upgrade requirements, call the Digital Equipment Corporation technical support line at 1-800-354-9000 in the U.S. for further assistance. For locations outside the U.S., contact your local authorized Digital representative. Digital Venturis Systems with S3 Based Video -------------------------------------------- The Digital Venturis line of computers with S3 based video may experience problems when attempting to restart. When selecting Shutdown/Restart, the system may freeze when attempting to reset the S3 video. This is in no way detrimental to the system, simply restart via the reset button or power off the computer. This issue will be addressed in the near future. Gateway Nomad and TI Travelmate Notebooks ----------------------------------------- To successfully install Windows NT on these machines, you must choose "Custom Setup." If you encounter problems running setup while scanning for SCSI Adapters, you can skip SCSI detection to solve the problem. To properly use the floppy drive with Windows NT, configure the system using its setup utility. Set the Advanced Operating System option to Auto. When power management drivers for these machines are available from Texas Instruments, using the Auto option will not be necessary. Installing Windows NT 3.51 on an IBM Personal Computer Power Series -------------------------------------------------------------------- When installing Windows NT 3.51 on an IBM Personal Computer Power Series, you will need an ARC Boot Diskette. The ARC Boot Diskette is shipped with each IBM Power Series System. If you do not have a copy of the diskette, or if you need an updated version, you may acquire a copy by contacting the IBM Windows NT support Center. In the USA call the IBM Help Center 800-772-2227. IBM Personal System/2 --------------------- On some IBM PS/2 systems only planar memory is recognized when booting from the Windows NT CD-ROM boot disk or Disk #1 of the floppy disk installation set. This is a memory card problem. You may encounter this problem if your system contains a card with the following part numbers: FRU-88F0075 Option 87F9856 or 87F9860 Newer model cards are available that correct this problem. Part numbers for the newer cards are: FRU-87F9916 or 34F2825 Option 34F3077 or 34F3011 Using Kingston expansion memory can also correct this problem. It is recommended that before you install Windows NT, you update your system configuration using the PS/2 Reference Diskette version 1.21 or later. IBM ThinkPad ------------ The IBM ThinkPad 700c and 720c portables require an ABIOS patch to install and run Windows NT. Copy the following files from the ThinkPad Reference Diskette onto C:\ ABIOS.SYS SF*.BIO Intel EtherExpress 16 LAN Adapter --------------------------------- In some cases, selecting "early" in the I/O Channel Ready box can stop the network adapter card from functioning correctly and may require reconfiguring with the Intel SoftSet utility. If you are unsure whether your system can take advantage of this network setting, consult your hardware vendor. Toshiba T4400SX Monochrome -------------------------- The Toshiba T4400SX display is not supported when an external monitor is connected. Caching Disk Controllers and Drives ----------------------------------- Windows NT supports caching disk controllers and drives only if one of the following is true: * The controller has a driver that specifically supports caching (several of these exist: DPT and IBM SCSI Caching Adapter). * Write-through is active (i.e. write caching is disabled) by setting it either manually or by default when the computer starts. * The entire cache option is off, by setting it either manually or by default when the computer starts. Using a caching controller or drive in other situations risks loss of data if the computer is rebooted or a power failure occurs before the cache has flushed itself. You can minimize risk by waiting at least 1 minute (less if you know the maximum time the cache waits before flushing itself) after all system activity stops before rebooting. The disk activity light is a good indicator of how write caching is being done on your system. This applies to the initial Windows NT installation as well as shutdown. Note that unexpected power failure at any time can potentially corrupt data on the disk, possibly to the extent that the disk becomes unreadable. Making the delay time that write data is cached before being flushed to disk as small as possible reduces this risk. Certain applications are data-sensitive and require that write-through is active. Examples of this are SQL Server-based applications and NTFS partitions. Installing Windows NT on an ESDI Disk Drive with More Than 1024 Cylinders ---------------------------------------- In some cases, on disk drives with more than 1024 cylinders, Windows NT installation proceeds normally until the first boot from the hard drive where Windows NT is installed. The Windows NT Boot Loader will load various files and then produce a Fatal System Error: 0x0000006b with the message that Phase 1 Process Initialization failed. Following this message will be some type of hexadecimal dump, and the system will be locked up. If you experience this difficulty, the following information can help. Microsoft has tested the ESDI controllers listed in README.WRI using a hard drive with a capacity exceeding 516 MB (MB=1,048,576 bytes) formatted. The MS-DOS limit of 1024 cylinders creates a situation where special BIOS mapping on the controller is used to change the geometry of the drive. ESDI drives are capable of being prepared with various values of sectors per track (spt) such as 53 or 63 spt geometry during a low- level format, as shown in the following example: 1024 cylinders x 15 heads x 53 spt x 512 bytes per sector = 398 MB formatted capacity - Or - 1024 cylinders x 15 heads x 63 spt x 512 bytes per sector = 472 MB formatted capacity Thus, using 63 spt will yield 74 MB more space. Windows NT is perfectly compatible with either geometry and, depending on the drive or controller, can access the remaining cylinders beyond 1024. This space can be partitioned and formatted but not accessed by MS-DOS. However, some controllers can successfully remap the remaining cylinders beyond 1024 so that either MS-DOS or Windows NT can use the entire capacity. For example: 1632 cylinders x 15 heads x 53 spt x 512 bytes per sector = 634 MB formatted capacity