Transistors to Supercomputers
Electronic engineers are exceptionally good at making hardware devices which are designed to operate in 2 distinct states - on and off (or high and low or polarized and not polarized or magnetized and not magnetized). Because of this, Modern computers store numbers using the binary number system. This numbering system uses just 2 symbols (usually "0" and "1") to represent the individual digits of a number. For example, the number 13 is written as 1101 in binary. One such binary device, which is at the foundation of all modern computers is the transistor.
Conceptually, the transistor is a simple device - it can be thought of as an electronic version of a water tap. A water tap has 3 essential connections - the input pipe, the output nozzle and the volume control. Similarly - the transistor has a "collector" (input pipe), an "emitter" (output nozzle), and a "base" (volume control). Instead of controlling the flow of water molecules, a transistor controls the flow of electrons.
Transistors can be configured to electronically turn the "tap" (base) ON or OFF very quickly, and indirectly represent a single binary digit. It takes millions of transistors wired together in intricate patterns to form the heart of a computer or "Central Processing Unit" (CPU).
A Pentium 4 contains about 55 000 000 transistors and
executes almost 2 billion instructions per second.
"Supercomputers" are built by using a parallel architecture - wherein thousands of individual processors are processing numbers in parallel. At the time of this writing (2003) the fastest supercomputer in the world is Japan's "Earth Simulator". It has the processing power of 20 000 Pentium 4 machines.
NEC's "Earth Simulator" supercomputer
Computer systems fall broadly into 4 architectures
- Scalar - an ordinary single - CPU machine
- Super-Scalar - a CPU which can execute more than 1 instruction at a time under some circumstances
- Vector - a CPU which can execute the same instruction on many simulatenous numbers
- Parallel - a series of CPUs which operate on different instructions at the same time.
The "Earth Simulator" uses a vector based architecture - an approach which American computer manufacturers had abandoned more than a decade ago.