I remember Steve Furber told us in CS that the first time he tested the original ARM they got back from the fab, they forgot to connect the power lines. It worked anyway, just from the power on the I/O lines.
SF The ARM was conceived as a processor for a tethered desktop computer, where ultimate low power was not a requirement. We wanted to keep it low cost, however, and at that time, keeping the chip low cost meant ensuring it would go in low-cost packaging, which meant plastic. In order to use plastic packaging, we had to keep the power dissipation below a watt—that was a hard limit. Anything above a watt would make the plastic packaging unsuitable, and the package would cost more than the chip itself.
We didn't have particularly good or dependable power-analysis tools in those days; they were all a bit approximate. We applied Victorian engineering margins, and in designing to ensure it came out under a watt, we missed, and it came out under a tenth of a watt—really low power.
