RTL/2
RTL/2 is a high-level programming language used for the development of real-time systems. It is mainly used for designing and implementing time-critical applications such as control systems, embedded systems, and robotics.
Hello, world code example:
TITLE Goodbye World;
LET NL=10;
EXT PROC(REF ARRAY BYTE) TWRT;
ENT PROC INT RRJOB();
TWRT("Hello world!#NL#");
RETURN(1);
ENDPROC;
Popularity: Less than 1% of developers are using or have used this language.*
*According to StackOverflow's 2023 survey.