Microsoft 32-bit disk access

32-bit Disk Access refers to a special disk-caching and writing mode available in 32-bit operating systems, that may or may not run purely 32-bit appplications. Sometimes enabling this mode on older operating systems would break older applications of the day.

Windows 3.1

Windows 3.1 had an option in its 386 Enhanced control panel that would enable 32-bit read & write access. Usually, 32-bit read could be safely enabled, but 32-bit write had issues with a number of applications.

Windows 9x

Windows 95, Windows 98, and Windows ME use protected mode disk drivers that are 32-bit in nature.

Safe Mode uses real mode disk drivers that disable native OS 32-bit disk access.

Mac OS 7

System 7 (Macintosh) has a "32-bit Addressing" mode in its Memory control panel that forces the OS to operate in its pure 32-bit mode; otherwise, it would operate in a 24-bit/32-bit hybrid mode. Some applications would refuse to work with this mode enabled.

Reference: Mac OS memory management

Other Operating Systems

Newer versions of Windows, Linux, and Mac OS all have 32-bit disk drivers active by default.

References

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