Using Third-Party Disk Management Utilities in Windows NT

• Microsoft Windows NT operating system, version 3.1
• Microsoft Windows NT Advanced Server, version 3.1

Most MS-DOS-based disk management utilities directly access the hard disk by calling MS-DOS Interrupt 13, Interrupt 25, and Interrupt 26. The disk I/O model in Windows NT prevents direct access to the hard disk; an application must call a trusted device driver for access. This prevents an application from compromising the integrity any robustness of the operating system.

Some utilities may continue to work, at least in part. For example, the Xtree disk management utility has two modes: one that writes directly to the disk and another that uses the regular MS-DOS file access functions. The latter mode works correctly in Windows NT.

If an application attempts to directly access the disk, the MS-DOS subsystem displays a message stating that an application attempted to issue an illegal call. You then have the option to terminate the application or to ignore the call.