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My Ghost in the Machine, a Particular Shade (of Grey)

This story dates back to my college days, and I use it to illustrate the idea that IT people are not entirely comfortable with other functional areas of the business – and the “shades of grey” that mysteriously guide the thinking and actions of Sales & Marketing, Strategic Planning, and Upper Management (especially when those IT folks are fresh out of school).

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Ok, quick aside – it’s been a few years since my undergraduate days, so if I get any of the technical details aside, give me a break – its just a dainty bit of prose to make a point

My undergraduate degree is in Electrical Engineering (double-E, or EE*); with all of my electives in Chips & Wires and Systems Programming classes, they would call it a Computer Engineering degree these days. Modern systems architecture may have a few added layers of abstraction, but there isn’t much difference from the basic constructs, with the fundamental concept of the binary switch (On! Off!) representing a single “bit” of information at the heart and soul (as it were) of the computer.

Of course, since it was an EE degree, I had to take my fair share of courses on electronics and circuits – the bones and blood vessels of your typical computer. And in second semester Circuits, we learned about the foundational electronic component of the modern era – the Transistor, that magical three-lead device that we use to represent this fundamental On-Off switch.

In this particular session, the professor was at the board drawing a wave form of the voltage across the two leads of the transistor. “When the voltage here moves up to 1.0 volts, we say the ‘switch’ is in the ‘on’ state (True, 1, Yes). And, when we change the inputs and the voltage is set to 0.0 volts, we say the ‘switch’ is in the ‘off’ state (False, 0, No).”

“However”, continued the teacher, “this is, after all, a physical device, and your designs have to account for certain material variations, loss across the devices, etc. So strictly speaking, we say that any voltage from 0.7 to 1.0 can be considered ‘on’ (True, 1, Yes). And, any voltage value from 0.0 to 0.3 can be considered ‘off’ (False, 0, No).”

Now, when most people remember stories from the past, they always get better in the telling – but truly, I remember that I was the smart aleck in the room that dutifully raised my hand to ask “what if the voltage is 0.4 or 0.5?”

“Well’, said the teacher, “then you have an ‘indeterminate state’ – neither 1 nor 0, on or off – and that is a problem in your circuit. It is up to the circuit designer to make sure the input values have enough power to get a clean reading of the state of the switch”.

And I sat back, slightly taken aback as I realized – even the digital computer, that bastion of black-and-white certainty, must deal with shades of grey.

The realization of that might give some computer engineers nightmares

* And remember, you can’t spell ‘geek’ without a double-E …

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