Information Technology Reference
In-Depth Information
Physical Characteristics of the CPU
Most CPUs are collections of digital circuits imprinted on silicon wafers, or chips, each no
bigger than the tip of a pencil eraser. To turn a digital circuit on or off within the CPU,
electrical current must flow through a medium (usually silicon) from point A to point B.
The speed the current travels between points can be increased by reducing the distance be-
tween the points or reducing the resistance of the medium to the electrical current.
Reducing the distance between points has resulted in ever smaller chips, with the circuits
packed closer together. In the 1960s, shortly after patenting the integrated circuit, Gordon
Moore, former chairman of the board of Intel (the largest microprocessor chip maker), hy-
pothesized that progress in chip manufacturing ought to make it possible to double the
number of transistors (the microscopic on/off switches) on a chip roughly every two years.
When actual results bore out his idea, the doubling of transistor densities on a single chip
every two years became known as Moore's Law , and this “rule of thumb” has become a goal
that chip manufacturers have met for over four decades. As shown in Figure 3.3, the number
of transistors on a chip continues to climb.
Moore's Law
A hypothesis stating that transistor
densities on a single chip double
every two years.
Figure 3.3
Moore's Law
Transistor densities on a single chip
double about every two years.
(Source: Intel Web site Moore's Law:
Made Real by Intel Innovation,
www.intel.com/technology/
mooreslaw/?iid=search, accessed
January 9, 2008.)
In what Gordon Moore touted as “the biggest change in transistor technology in 40
years,” 5 Intel created its next generation 45-nanometer (one-billionth of a meter) Penryn
chip—so small that more than 2 million such transistors can fit in the period at the end of
this sentence. The new Core 2 processor chips enable extremely high processing speeds at
very low power usage. The design is based on a new material called “high-k.” The material
replaces the thin layer of silicon dioxide insulation that electrically isolates the transistor's
gate from the channel through which current flows when the transistor is on. 6 Intel is on
track to deliver a 32-nanometer chip in 2009.
Moore's Law enables chip makers to improve performance by putting more transistors
on the same size chip and at the same time reduce the amount of power required to get work
done. Furthermore, since the chips are smaller, chip manufacturers can cut more chips from
a single silicon wafer and thus reduce the cost per chip. As silicon-based components and
computers gain in performance, they become cheaper to produce, and therefore more plen-
tiful, more powerful, and more a part of our everyday lives.
Intel has defined a new manufacturing strategy to introduce chips and manufacturing
technologies every two years. Intel refers to this as their “tick-tock” strategy, which will drive
Intel to make smaller changes to its chip designs more frequently. Intel needs this kind of
continuous improvement effort to avoid getting caught off guard as it did early in the twenty-
first century when AMD introduced a new chip architecture that yielded significant
improvement and power efficiency over Intel chips. 7
 
 
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