General-purpose fictional computer: MIX, MIXAL Hello World Example

TERM    EQU    19          console device no. (19 = typewriter)
        ORIG   1000        start address
START   OUT    MSG(TERM)   output data at address MSG
        HLT                halt execution
MSG     ALF    "HELLO"
        ALF    " WORL"
        ALF    "D    "
        END    START       end of program