Windows 2.1
... that Windows 2.1 was the first version of Microsoft Windows to require a hard disk drive?
... that <b id="mwBU4"><a class="mw-redirect" href="./Windows_2.1x" id="mwBU8" rel="mw:WikiLink" title="Windows 2.1x">Windows<span id="mwBVA" typeof="mw:Entity"> </span>2.1</a></b> was the first version of <a href="./Microsoft_Windows" id="mwBVE" rel="mw:WikiLink" title="Microsoft Windows">Microsoft Windows</a> to require a <a href="./Hard_disk_drive" id="mwBVI" rel="mw:WikiLink" title="Hard disk drive">hard disk drive</a>?