MASER

The MASER (an acronym for "Microwave Amplification and Stimulated Emission of Radiation") was a weapon acting like a particle disseminator — that is, it was able to disseminate even subatomic particles, including gravitons, quarks and tau mesons.

The Valeyard built one in the Matrix, with the aim to kill everyone watching it. Melanie Bush incorrectly called it a 'megabyte modem'. (TV: The Ultimate Foe)