Wednesday, October 23, 2013

Music and girls cause boy engineers to kill people unknowingly

There was an engineer. He had been partying all weekend with his peeps at NH7 weekender 2013, Pune. He loved every moment of it. Specially when on the last day the performers urged the crowd to shout "Fuck that shit" in unison. It was thrilling. He shook his neck with the crowd with every chant, the last of which caused his head to come real close to the mouth of a girl making her way to the front. "Excuse me" she said. Her words missed in the loudness, but a few fragments of virii from her breathe made way into his mouth as he breathed in for the next chant.

Its Monday, he is at his office in Pune and suffering from viral infection. The agony induced by illness decreased his attention level at work. He was working on the layout of an ASIC for a baseband processor. A sneeze and an involuntary contraction later, a channel was offset by 5 nm from its intended location. The chip turned out OK. All tests were passed. Except that a series of cascade events (80.67 deg celsius temperature + battery at 75.3% causing power supply to baseband chip at exactly 3.145 volts) causes the unintentional parasitics to boost the BER to extreme levels for a few seconds.

Another engineer buys a phone. It has this baseband processor in it. This engineer has OCD. He always charges his phone for 1 hour at 8 am when he reaches office daily on time. So his battery level crosses 75.3% everyday somewhere around afternoon, exact time being dependent on his usage and ambient weather conditions. He lives and works in Delhi, India. He has a girl friend who is contemplating breaking up with him. It's summer. They are whatsappingeach other. He is trying his best to put forward his case to get her to reconsider breaking up with him. He is winning but the whole conversation is taking its toll on him. Anxiety levels are high. His phone on vibration only (silence must be observed in office) constantly clutched in his hand is draining its battery and his body head is causing phone to warm up. The baseband processor is hot from all the data passing through it.

His hand has increased the thermal resistance and the baseband processor is working up its internal temperature.

Battery draining towards 75.3%...

Power to the chip falling very slowly towards 3.145 volts...

The chip itself warming up to 80.67 degrees...

Anxiety levels increasing...

And finally it happens... The intersection of those exact conditions occurs and the RF receiver frontend of the baseband processor destabilizes and it's Bit Error Rate rises exponentially. A few milliseconds later, the chip resets itself and the message from his girlfriend reaches him exactly 3.14159 seconds later than the time it would have reached him if the baseband processor hadn't reset. The phone vibrates at the opportune time while he was compiling the release binary for the code he was working. The vibration steals his attention away from his screen which is scrolling build messages. His girlfriend isn't going to break up with him. He is happy. A minor warning from the compiler goes un-noticed.

A few years later, that software (that the 2nd engineer was working on) which runs inside a pacemaker kills 3 of its 9,576 owners. A stack overflow on the 37th impulse caused the next 3 impulses to be displaced by 200 milliseconds as the software recovered during a cardiac event occurring exactly 49.7 days after the previous event.


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