An interesting piece about the 3.5mm audio connector from the BBC:<p><i>The 19th Century plug that&#x27;s still being used</i><p><i>&quot;The 3.5mm headphone jack is essentially a 19th Century bit of kit - it is a miniaturised version of the classic quarter-inch jack (6.35mm), which is said to go back as far as 1878.&quot;</i><p><a href="http:&#x2F;&#x2F;www.bbc.co.uk&#x2F;news&#x2F;magazine-35253398" rel="nofollow">http:&#x2F;&#x2F;www.bbc.co.uk&#x2F;news&#x2F;magazine-35253398</a>