Why USB-A Goes In Wrong Twice

The USB-A plug has a top and a bottom, and you almost always insert it wrong the first time. Ajay Bhatt, the Intel architect who led the design team in 1994, has admitted this was a deliberate tradeoff that his team made badly.

A reversible plug needs wires routed symmetrically on both faces, so the same contact pad lands on the same pin whichever way you flip the connector. That means either double the wiring in the cable, or a small switching circuit inside the plug. In 1994, adding that circuit would have added measurable cost to every cable — pennies that, at a billion cables a year, would mean tens of millions of dollars.

Bhatt's team ran the numbers and decided the asymmetric design was good enough. A user who guesses wrong simply flips the plug and tries again; a cost increase of twenty percent per cable persists forever.

In a 2019 NPR interview, Bhatt called this his biggest regret. "The biggest annoyance is reversibility," he said. USB-C, introduced in 2014, has 24 symmetric pins and genuinely works either way. It took two decades and a different team to undo the choice.