IBM 2741

[1] Compared to the teletypewriter machines that were commonly used as printing terminals at the time, the 2741 offers 50% higher speed, much higher quality printing, quieter operation, interchangeable type fonts, and both upper and lower case letters.

In contrast to serial terminals employing ASCII code, the most significant data bit of each character is sent first.

The machine was packaged into its own small desk, giving the appearance of square tabletop with a Selectric typewriter partly sunken into the surface, with the electronics in a vertically oriented chassis at the rear.

The two varieties of IBM 2741 use different character codes on the serial interface as well, so software in the host computer needed to have a way to distinguish which type of machine each user had.

One way this was accomplished was by having the user type a unique character such as # , 9 [6] or a standard command such as "login" immediately after connecting.

Upon receipt of the "circle C" the local 2741 unlocks its keyboard and the operator can send another input to the system.

ATS is an interactive, multi-user text editing and storage system implemented in the mid-1960s using IBM System/360 assembly language.

As originally proposed by Dr. Kenneth Iverson, APL required a large variety of special characters.

The "shifted" keystroke characters provided many of the special symbols with the remainder being handled by overstrike.

Some later IBM Selectric-based machines, such as the Communicating Magnetic Card Selectric Typewriter, can emulate the 2741 and be used in its place.

IBM sold the underlying Selectric mechanism to other manufacturers, who produced 2741 clones at lower cost.

For example, a 2741-type mechanism formed the principal user interface for a series of machines from the 1960s and 1970s built in the United Kingdom by Business Computers Ltd.