Installing Windows NT on a Large IDE Hard Disk

by Wayne Maples [Published on 20 April 2004 / Last Updated on 20 April 2004]

During the text-based portion of the NT installation, it is possible to create and format partitions. NT installation prior to SP4 uses a generic IDE driver, atapi.sys , which is not fully compatible with IDE drives larger that 8 GB. Most NT installation CDs are SP1. With the older atapi driver any of these symptoms can occur :
  • computer hangs during the format portion of setup
  • computer hangs during fat->ntfs conversion process
  • drive takes extremely long time to format
  • Windows NT does not recognize the entire size of the drive

The SP4 and later atapi.sys is compatible with greater than 8 GB IDE hard drives. The system partition of the drive (where NT boots) must be installed within the first 7.8GB of the hard drive. The install partition is limited to 4GB. The partitioning rules Windows NT uses during Setup are laid out clearly in Windows NT Partitioning Rules During Setup. The 4GB limitation is mentioned there and covered also in int13 limitations. Windows NT will only be able to access greater than 8GB drives if your PCs motherboard and BIOS recognizes and supports large HDs. You may have to update your PC BIOS to get this support.

The installation process with SP1 is:

  • download updated atapi.exe
  • Copy atapi.exe to a blank floppy disk
  • Run Atapi.exe on the diskette and Atapi.sys file will be extracted to the diskette
  • label the disk Microsoft ATAPI Service Pack 4 IDE Driver
  • Start Windows NT install using 3 NT boot disks.
  • When asked if you would like setup to detect your mass storage devices, press S so that detection is skipped and you specify a mass storage device.
  • When setup list devices found, which should list , press S again and insert the Microsoft ATAPI Service Pack 4 IDE Driver disk and press ENTER twice Setup will now list Microsoft ATAPI Service Pack 4 IDE Driver as an installed driver.
  • Continue setup and during the copy phase NT will prompt you for the atapi driver diskette.
Remember you can install Windows NT on a system partition from 1GB to 7.8GB. The rest of the HD must be another partition (s).

The process is slightly different if installing using Microsoft Small Business Server 4.0 or 4.0a. See Q197667 which is the source for this tip and includes variant for SBS server.

A related issue involves dual-boot for Windows NT and Win95/Win98. Win9x must be installed on FAT16 (since NT will not boot to fat32) which constraints the system partition to 2GB.

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