An isolinear subprocessor was a computer core subsection containing isolinear optical chips. A better term for it would be a processor block.

At one point in 2367, Worf and Riker are working inside of a Jefferies tube on an isolinear subprocessor that included panel J-14 Baker. This panel connected to Science Station Two, and functioned as part of the USS Enterprise-D's life support system. (TNG: "Brothers")