Windows 95 Setup Switch to Skip MS-DOS Disk Utilities

During the installation of Windows 95, the /it command-line switch allowed users to bypass the automated scan for conflicting terminate-and-stay-resident (TSR) programs and existing MS-DOS disk utilities. Microsoft introduced this switch to give technicians and advanced users a way to force the setup routine to proceed even if legacy utilities or false positives caused the installer to halt.

The Purpose of the /it Switch

When starting installation via the command line, running setup /it instructed the Windows 95 installer to ignore its built-in detection routine for legacy disk software and resident programs.

By default, Windows 95 checked for third-party MS-DOS disk management tools, such as older versions of Norton Utilities, Central Point PC Tools, real-mode disk caches, and background defragmenters. These tools posed significant risks to the new operating system because they were unaware of the VFAT file system and Long File Names (LFNs). Running incompatible DOS utilities alongside the installation could lead to corrupted File Allocation Tables, truncated file names, or setup crashes.

Common Use Cases

While Microsoft recommended allowing the scan to run, the /it switch was useful in several practical scenarios:

• Overcoming False Positives: Some harmless or updated MS-DOS drivers and utilities triggered the installer's conflict warning, preventing setup from continuing.
• Automating Deployments: Network administrators deploying Windows 95 across multiple identical machines often skipped unnecessary detection routines to save time.
• Troubleshooting and Maintenance: When reinstalling Windows 95 in recovery scenarios where disks were already verified, skipping TSR checks helped streamline system restoration.

The /it switch was frequently combined with other setup switches—such as /is to skip the initial ScanDisk run or /im to bypass the conventional memory check—using commands like setup /is /it to produce the fastest possible installation path.