1960
Developed in 1949 for transmitting radar signals by Jack Harrington’s group at the Air Force Cambridge Research Center (AFCRC) near Boston, the modem modulates digital data into sounds, and demodulates received sounds into digital data (MODulation + DEModulation = MODEM). Modems will be adapted to computers in 1953 for the upcoming SAGE system, and commercialized by Bell Telephone in 1958. By letting computers use normal voice telephone lines, they offer greater coverage and lower costs than dedicated telegraph or leased data lines.
The advent of MOSFET technology, integrated circuit chips and shift register MOS memory led to the application of solid-state microelectronic semiconductor technology and digital circuitry to the implementation of digital multi-channel modems. This enabled advantages such as a very small size, light weight, stability, high reliability, low cost, and freedom from adjustment.
Links:
AT&T Tech Channel