An anonymous reader writes with a link to the observation from ZDNet's Mary Jo Foley of Windows NT's 20th birthday
(it came out on July 27th, 1993): ""In 1993, Microsoft launched Windows NT 3.1. It was followed up by NT 3.5, 3.51 and 4.0. Microsoft's Windows releases still rely on NT-inspired numbering conventions. Windows 7's build numbers commenced with 6.1; Windows 8's with 6.2; and Windows 8.1 with 6.3." The article also reminds us that "NT's not ancient history, in spite of its age. The NT 'core' is what's inside Windows 8, Windows Server 2012, Windows Phone 8, Windows Azure and the Xbox One.""