PL/M

PL/M is a high-level programming language used primarily for embedded systems and microcontrollers, known for its simplicity and efficiency. It is commonly used in industrial automation, telecommunications, and other low-level programming applications.

Hello, world code example:

100H:
   /* CP/M BDOS SYSTEM CALL */
   BDOS: PROCEDURE( FN, ARG ); DECLARE FN BYTE, ARG ADDRESS; GOTO 5; END;
   /* PRINT A $ TERMINATED STRING */
   PRINT$STRING: PROCEDURE( S ); DECLARE S ADDRESS; CALL BDOS( 9, S ); END;
   /* HELLO, WORLD! IN MIXED CASE */
   DECLARE HELLO$WORLD ( 14 ) BYTE
           INITIAL( 'H', 65H, 6CH, 6CH, 6FH, ',', ' '
                  , 'W', 6FH, 72H, 6CH, 64H, 21H, '$'
                  );
   CALL PRINT$STRING( .HELLO$WORLD );
EOF

Popularity: Less than 1% of developers are using or have used this language.*
*According to StackOverflow's 2023 survey.

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