TRN Glossary P

Parallel System: A computer that uses two to thousands of processors at once. Parallel Systems software assigns portions of individual problems to each processor then combines the results. Problems that can be broken into multiple parts, like analyzing large amounts of scientific data, can be solved much faster by Parallel Systems than by single processor systems.

Pattern Recognition: Picking out meaningful patterns from a large amount of data such as a digitized image. Pattern Recognition algorithms are the basis for speech recognition software and computer vision systems. Pattern Recognition software is also used to sort through vast amounts of scientific data.

Photolithography: The "etching with light" technique used to make integrated circuits. In this technique, a layer of silicon or other semiconductor is covered by a protective oxide layer which in turn is covered by a polymer that reacts to light. A mask outlining desired circuits is laid on top, then the masked polymer is exposed to light. The light chemically changes the exposed areas of the polymer. Chemicals are then applied to wash away the exposed polymer and the oxide underneath. The remaining polymer is washed away with other chemicals, leaving the layer of oxide in the form of the mask and the layer of silicon exposed in the pattern of the desired circuits. The exposed silicon is then "doped," or chemically altered, to become more electrically conductive. This forms the transistors and logic gates of the chip.

Photonics: Using rapid pulses of light to transmit data. Photonics underlie much of modern telecommunications and enable experiments in optical computing.

Probabilistic Reasoning: Calculating probabilities in order to make predictions or decisions based on otherwise insufficient information. Probabilistic Reasoning is used in Artificial Intelligence. Probabilistic Reasoning is particularly important to the evolution of computing because traditional computer systems are incapable of handling uncertainty, which makes them ill equipped to deal with humans or the world at large.

Programming Language: A system for writing software programs that, like human languages, has a syntax and semantics. A programming language provides a consistent framework for writing and combining algorithms.

Protocol: An agreed-upon set of rules that facilitates the exchange information between two computers or devices. Standardized protocols are used in computer networking. IP, TCP, FTP and HTTP are all network protocols.