<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"><head><meta http-equiv=Content-Type content="text/html; charset=us-ascii"><meta name=Generator content="Microsoft Word 15 (filtered medium)"><style><!--
/* Font Definitions */
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0in;
margin-bottom:.0001pt;
font-size:11.0pt;
font-family:"Calibri",sans-serif;}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:#0563C1;
text-decoration:underline;}
span.EmailStyle17
{mso-style-type:personal-compose;
font-family:"Calibri",sans-serif;
color:windowtext;}
.MsoChpDefault
{mso-style-type:export-only;
font-family:"Calibri",sans-serif;}
@page WordSection1
{size:8.5in 11.0in;
margin:1.0in 1.0in 1.0in 1.0in;}
div.WordSection1
{page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</o:shapelayout></xml><![endif]--></head><body lang=EN-US link="#0563C1" vlink="#954F72"><div class=WordSection1><p class=MsoNormal>Another candidate record I was thinking about was the longest lived computer architecture. Longest lived here being the uninterrupted production and sale of machines. (So retro revivals don’t count). Architecture being able to run object code without recompilation, and without emulation.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I’m assuming that would be the IBM System/360, with the /370, /380 etc. being considered extensions of the same architecture. It is widely claimed (e.g. by Wikipedia) that even the current IBM Z family of mainframes has retained compatibility with the System/360 (<a href="https://en.wikipedia.org/wiki/IBM_Z">https://en.wikipedia.org/wiki/IBM_Z</a>) such that “Many applications written for these systems can still run unmodified on the newest IBM Z system over five decades later.” Although as virtualization is so central to mainframe architecture form the 1970s onward I don’t have a clear sense of how much of this is straightforward hardware compatibility and how much is provided by the virtualization software.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>If we accept this as an uninterrupted architecture, then that give 1964 to 2020, or 56 years and counting. That appears to be longer than the Intel 8086, which has been incrementally extended to the present day, with the x64 architecture, and was launched in 1978, making it 42 years old. <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>I know that some of the first System/360 models included emulation of even earlier machines, and that the original 8086 was designed with early conversion from earlier Intel chips in mind. But in both cases they seem distinct enough to set a new standard.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>An I missing any other contenders? Or does anyone know enough to make a case that, contrary to popular belief, true System/360 hardware compatibility was lost at some point?<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Tom<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>