Month: July 2014

The Deep Computing Lessons of Apollo

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Apollo 11With the arrival of the Apollo 11 mission’s 45th anniversary, and occasional planning and dreaming about a manned mission to Mars, the role of information technology comes again into focus. The next great mission will include a phalanx of computing resources, sensors, radars, hyper spectral cameras, laser rangefinders, and information fusion visualization and analysis tools to knit together everything needed for the astronauts to succeed. Some of these capabilities will be autonomous, predictive, and knowledgable.

But it all began with the Apollo Guidance Computer or AGC, the rather sophisticated for-its-time computer that ran the trigonometric and vector calculations for the original moonshot. The AGC was startlingly simple in many ways, made up exclusively of NOR gates to implement Arithmetic Logic Unit-like functionality, shifts, and register opcodes combined with core memory (tiny ferromagnetic loops) in both RAM and ROM forms (the latter hand-woven by graduate students).

Using NOR gates to create the entire logic of the central processing unit is guided by a few simple principles. A NOR gate combines both NOT and OR functionality together and has the following logical functionality:

[table id=1 /]

The NOT-OR logic can be read as “if INPUT1 or INPUT2 is set to 1, then the OUTPUT should be 1, but then take the logical inversion (NOT) of that”. And, amazingly, circuits built from NORs can create any Boolean logic. NOT A is just NOR(A,A), which you can see from the following table:

[table id=2 /]

AND and OR can similarly be constructed by layering NORs together. For Apollo, the use of just a single type of integrated circuit that packaged NORs into chips improved reliability.

This level of simplicity has another important theoretical result that bears on the transition from simple guidance systems to potentially intelligent technologies for future Mars missions: a single layer of Boolean functions can only compute simple things.… Read the rest

Just So Disruptive

Mark DavisLeave a comment

i-don-t-always-meme-generator-i-don-t-always-buy-companies-but-when-i-do-i-do-it-for-no-reason-925b08The “just so” story is a pejorative for cultural or physical traits that drive an evolutionary explanation. Things are “just so” when the explanation is unfalsifiable and theoretically fitted to current observations. Less controversial and pejorative is the essential character of evolutionary process where there is no doubt that genetic alternatives will mostly fail. The ones that survive this crucible are disruptive to the status quo, sure, but these disruptions tend to be geographically or sexually isolated from the main population anyway, so they are more an expansion than a disruption; little competition is tooth-and-claw, mostly species survive versus the environment, not one another.

Jill Lapore of Harvard subjects business theory to a similar crucible in the New Yorker, questioning Clayton Christensen’s classic argument in The Innovator’s Dilemma that businesses are unwilling to adapt to changing markets because they are making rational business decisions to maximize profits. After analyzing core business cases from Christensen’s books, Lapore concludes that the argument holds little water and that its predictions are both poor and inapplicable to other areas like journalism and college education.

Central to her critique is her analysis of the “just so” nature of disruptive innovation:

Christensen has compared the theory of disruptive innovation to a theory of nature: the theory of evolution. But among the many differences between disruption and evolution is that the advocates of disruption have an affinity for circular arguments. If an established company doesn’t disrupt, it will fail, and if it fails it must be because it didn’t disrupt. When a startup fails, that’s a success, since epidemic failure is a hallmark of disruptive innovation. (“Stop being afraid of failure and start embracing it,” the organizers of FailCon, an annual conference, implore, suggesting that, in the era of disruption, innovators face unprecedented challenges.

… Read the rest