It was used primarily with the IBM System/360 series of computers, but
was used with other IBM and non-IBM systems where its combination of
higher speed and letter-quality output was desirable.[2][3][4] It was
influential in the development and popularity of the APL programming
language

The IBM 2741 combines a ruggedized Selectric typewriter mechanism with
IBM SLT electronics and an RS-232-C serial interface. It operates at
about 14.1 characters per second with a data rate of 134.5 bits/second
(one start bit, six data bits, an odd parity bit, and one and a half
stop bits). In contrast to serial terminals employing ASCII code, the
most significant data bit of each character is sent first.

The IBM 2741 came in two different varieties, one using "correspondence
coding" and the other using either "PTT/BCD coding" or "PTT/EBCD
coding".

Similar to APL, ALGOL 68 was defined with a large number of special
characters. Many of them ( ∨, ∧, ¬, ≠, ≤, ≥, ×, ÷, ⌷, ↑, ↓, ⌊, ⌈ and ⊥ )
were available on the APL Selectric typeball, so this element was used
to prepare the ALGOL 68 programming language standard Final Report
(August 1968), even though APL and ALGOL have no direct relationship. 

The APL version had only 26 alphabet characters (upper case), and
instead of lower case, symbols with shift for APL use were defined.
These version use special selectric typeball.

Note. The communication was using 6 bits of data. Extra characters were
supported by sending special shift in or shift out codes to almost
double code space. The shifting functionality was briefly considered
during developement of ASCII, but it was decided that plain 7-bit
encoding would be better for reliability.