noun: (electronics) Initialism of printed circuit board. [(electronics) A flat board that holds chips and other electronic components in layers that interconnect via copper pathways, often called traces.]
noun: (organic chemistry) Initialism of polychlorinated biphenyl. [(organic chemistry) Any of a class of aromatic organic compounds formed by the chlorination of the hydrocarbon biphenyl; they have many industrial applications but are now considered persistent organic pollutants.]
noun: (informatics) Initialism of program control block.
noun: (electronics) Initialism of physically changeable bit.