The Pennywhistle was an early acoustic coupler modem originally designed and built by Lee Felsenstein in 1973, and later commercialized and offered for sale in 1976. It was one of the earliest modems available for hobbyist computer users.[1] Like most acoustic coupler modems, the Pennywhistle was replaced by the Hayes Smartmodem and similar models from the early 1980s.
- ^ Roy Allan, "A History of the Personal Computer: The People and the Technology", Allan Publishing, 2001, pg. 17