The Old New Thing

Why does Windows keep your BIOS clock on local time?

September 2, 2004 Sep 2, 2004 09/2/04

Raymond Chen

Even though Windows NT uses UTC internally, the BIOS clock stays on local time. Why is that? There are a few reasons. One is a chain of backwards compatibility. In the early days, people often dual-booted between Windows NT and MS-DOS/Windows 3.1. MS-DOS and Windows 3.1 operate on local time, so Windows NT ...