Windows NT 3.1 build 528

Windows NT 3.1 build 528.1 is the second RTM build of Windows NT 3.1, released two months after the original RTM (build 511). It introduced support for the Alpha architecture and included the first set of bugfixes for build 511, which were also released separately in the form of a service pack. This build is also often referred as the Service Pack 3 of Windows NT 3.1. It is available as a full operating system and as an update for build 511.1.

There is also a Compaq OEM version of this build (dated 1994-01). It contains a modified setup boot disk image and some additional files, and is an AIO disc containing both client and server builds in several languages; the modified setup boot disk allows for choosing the language and SKU. However, registry hives are encrypted, and a license floppy containing the encrypted encryption key is required to install; the key encryption key is a floppy-specific product key that is requested after the license disk by SETUPAPP.