Teletype Model 35ASR

The Teletype Model 33 ASR is an electro-mechanical teleprinter designed for light-duty office use as an input (typing), output (printing), and storage (paper tape) device. As a teleprinter, the Teletype Model 33 ASR can be used to send and receive messages through communication channels reached through its 110 Baud modem. The ASR in the name stands for Automatic Send and Receive because with this model does not need an operator to aid in receiving messages during transmissions as long as the connection remained unbroken.

The Teletype Corporation introduced this model version and two others in 1967 as more refined and less expensive than earlier Teletype machines. Prior to 1967, the Teletype Model 33 was a non-commercial product designed for use in the US Navy.

This one had a built in 8-level punched tape reader and tape punch and was one of the first products to use the American Standard Code for Information Interchange (ASCII) based on a character-encoding scheme. It had hammer keys for impact printing, a fixed sized font with fully formed letters. The Model 33 was very popular in the industry due to its low price of about $700, use of ASCII code, and compatibility to use with early minicomputers. Over 600,000 models were sold. The design of this model was geared to fit in small offices, match with other office equipment, and operated for light duty use (around 2 hours a day on average). At max speed the Model 33 operate at about 100 words per minute.

The introduction of integrated circuits and semiconductor memory phased out the Teletype Model 33 and its production ceased in 1981.