<story><title>Ask HN: What is the oldest, still supported OS?</title><text>I recently discovered that TSOS, an old Univac OS that I used (and loved!) in the mid 1970&amp;#x27;s and first released in 1968 by RCA, is still supported (although the name has changed) as Fujitsu&amp;#x27;s BS2000 OS. Unix was released a year after that (1969). Is there something that beats these?</text></story><parent_chain><item><author>alexvoda</author><text>I find it interesting that you write years using 5 digits with leading zeroes. Can you tell me more about that choice?</text></item><item><author>kragen</author><text>Burroughs MCP was released in 01961 and seems to still be supported.  The latest release was 20.0 in May.  That&amp;#x27;s probably the oldest.&lt;p&gt;z&amp;#x2F;OS was released in 01966.  BOS&amp;#x2F;360 made it out the door earlier, in 01965, thanks to the disastrous delays in z&amp;#x2F;OS, but it&amp;#x27;s no longer supported; DOS&amp;#x2F;360 (z&amp;#x2F;VSE) also beat z&amp;#x2F;OS out, is still supported, and is arguably the continuation of BOS. &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;DOS&amp;#x2F;360_and_successors&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;DOS&amp;#x2F;360_and_successors&lt;/a&gt;&lt;p&gt;Unix wasn&amp;#x27;t released in 01969.  I think it wasn&amp;#x27;t released until Fifth Edition in 01974, though Thompson and Ritchie described the Fourth Edition in CACM in 01973.  Fourth Edition had &amp;quot;over 20&amp;quot; installations, but I think all within AT&amp;amp;T. &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;Research_Unix&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;Research_Unix&lt;/a&gt;</text></item></parent_chain><comment><author>compressedgas</author><text>&lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;longnow.org&amp;#x2F;ideas&amp;#x2F;02013&amp;#x2F;12&amp;#x2F;31&amp;#x2F;long-now-years-five-digit-dates-and-10k-compliance-at-home&amp;#x2F;&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;longnow.org&amp;#x2F;ideas&amp;#x2F;02013&amp;#x2F;12&amp;#x2F;31&amp;#x2F;long-now-years-five-di...&lt;/a&gt;</text></comment>
<story><title>Ask HN: What is the oldest, still supported OS?</title><text>I recently discovered that TSOS, an old Univac OS that I used (and loved!) in the mid 1970&amp;#x27;s and first released in 1968 by RCA, is still supported (although the name has changed) as Fujitsu&amp;#x27;s BS2000 OS. Unix was released a year after that (1969). Is there something that beats these?</text></story><parent_chain><item><author>alexvoda</author><text>I find it interesting that you write years using 5 digits with leading zeroes. Can you tell me more about that choice?</text></item><item><author>kragen</author><text>Burroughs MCP was released in 01961 and seems to still be supported.  The latest release was 20.0 in May.  That&amp;#x27;s probably the oldest.&lt;p&gt;z&amp;#x2F;OS was released in 01966.  BOS&amp;#x2F;360 made it out the door earlier, in 01965, thanks to the disastrous delays in z&amp;#x2F;OS, but it&amp;#x27;s no longer supported; DOS&amp;#x2F;360 (z&amp;#x2F;VSE) also beat z&amp;#x2F;OS out, is still supported, and is arguably the continuation of BOS. &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;DOS&amp;#x2F;360_and_successors&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;DOS&amp;#x2F;360_and_successors&lt;/a&gt;&lt;p&gt;Unix wasn&amp;#x27;t released in 01969.  I think it wasn&amp;#x27;t released until Fifth Edition in 01974, though Thompson and Ritchie described the Fourth Edition in CACM in 01973.  Fourth Edition had &amp;quot;over 20&amp;quot; installations, but I think all within AT&amp;amp;T. &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;Research_Unix&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;en.wikipedia.org&amp;#x2F;wiki&amp;#x2F;Research_Unix&lt;/a&gt;</text></item></parent_chain><comment><author>gumby</author><text>01961 is not a valid year as &amp;#x27;9&amp;#x27; is not a valid octal digit.</text></comment>