Biomedical Engineering Reference
In-Depth Information
Consider, for example, that at the dawn of the 20th Century, Walter Sutton was advancing the
chromosome theory just as transatlantic wireless communications was being demonstrated with a
spark-gap transmitter using Morse code. The state of the art in computing at the time was a
wearable analog time computer—the newly invented wristwatch. The remarkable fact about the
status of computing, communications, and biology at the dawn of the 20th Century is that all three
were nascent curiosities of a few visionaries. It's equally remarkable that the three technologies are
so pervasive today that they are largely taken for granted.
Two key events in the late 1920s were Alexander Fleming's discovery of penicillin and Vannevar
Bush's Product Integraph, a mechanical analog computer that could solve simple equations. In the
1930s, Alan Turing, the British mathematician, devised his Turing model, upon which all modern
discrete computing is based. The Turing model defines the fundamental properties of a computing
system: a finite program, a large database, and a deterministic, step-by-step mode of computation.
What's more, the architecture of his hypothetical Turing Machine—which has a finite number of
discrete states, uses a finite alphabet, and is fed by an infinitely long tape (see
Figure 1-3
)—is
strikingly similar to that of the translation of RNA to proteins. Turing theorized that his machine could
execute any mathematically defined algorithm, and later proved his hypothesis by creating one of the
first digital electronic computers.
Figure 1-3. The Turing Machine. The Turing Machine, which can simulate
any computing system, consists of three basic elements: a control unit, a
tape, and a read-write head. The read-write head moves along the tape and
transmits information to and from the control unit.
By the early 1940s, synthetic antibiotics, FM radio, broadcast TV, and the electronic analog computer
were in use. The state of the art in computing, the electronic Differential Analyzer occupied several
rooms and required several workers to watch over the 2,000 vacuum tubes, thousands of relays, and
other components of the system. Not surprisingly, for several years, computers remained commercial
curiosities, with most of the R&D activity occurring in academia and most practical applications
limited to classified military work. For example, the first documented use of an electronic analog
computer was as an antiaircraft-gun director built by Western Electric Company. Similarly, the first
