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Electronic devices are everywhere,
and they are getting smaller and smarter each year. The basic electronics
found in products like sprinkler timers, VCRs, and electric wristwatches
can be traced back to 1948 when the transistor was invented. The
beginnings of miniature, compact electronic intelligence really began in
1971 when Intel Corporation integrated a number of transistors to build
the first microprocessor. It was the brain of a desktop electronic
calculator, and it had over 2000 transistors.
At right is an example
of how integrated circuits become more compact, yet more capable.
The microprocessors in today's
electronics are usually single-chip integrated circuits mounted directly
on a circuit board (embedded). When a microprocessor chip is complete with
it's own memory, it is called a micro-controller. Both 'micro' devices are
integrated circuits that contain many thousands or even millions of
transistors and perform typical computer operations or instructions. When
incorporating them in medical devices, we have the choice of using
micro-controller chips alone, or combining them with the complex
circuitry of another class of programmable logic device called a
Field Programmable Gate Array (FPGA). FPGAs can allow great reduction in
circuit board size when used in place of circuits that are not easily
modeled in a micro-controller.
The information contained in program
memory guides the controller through a list of steps and decision points
one at a time. These "steps" are the language of the digital
world. Today's chips can
process each step very quickly, sometimes at the rate of millions of
instructions per second.
Speedier micro-controllers allow
programmers to write sophisticated software instructions that previous
embedded devices would have taken too long to perform. This increase in
calculation power has allowed us to engineer products that were not
previously possible. Real-time speaking valve performance assessment by
the lung simulator we built, and data collection systems in development at
Omnica, are only possible because of high-speed processors.
Small physical size sometimes masks the
complexity of today's electronics. New technologies have given us more
design and engineering latitude. Flex
circuits and surface mount electronic parts, smaller more powerful
embedded micro-controllers, and programmable logic devices make the
possibility of "stuffing 10 pounds of components into a one pound
box" a reality.
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