Hayes Smartmodem 300

Modem, 1981, Hayes Microcomputer Products. The Smartmodem 300 was the first modem that could be controlled entirely by commands sent from the computer over the serial line, the "AT" command set invented by Dale Heatherington and Dennis Hayes: dialling, answering and hanging up no longer needed switches or an acoustic coupler. The flat aluminium case with a row of LEDs became the model for external modems for the next fifteen years, and the Hayes command set is still used today.