Kentongan and smoke signals have long been used for communication in some communities. Epigraphy on Palmyra palms also served as an early messaging system. Modern communication tools include the telephone (invented in 1876), television (1883), telegraph (1840s), pagers, satellite phones, and the internet (originating from early computer networks developed starting in the 1960s). Calculation tools evolved from using body parts to knots, ropes, and early mechanical computers in the 1800s-1900s. This led to the development of programmable electronic digital computers across three generations from the 1940s-1960s.