Each line is read, translated into machine language, than executed. For compiled language, entire text file is read and translated, then stored. Compiled programs are faster. Compiled programs don't need compiler to run. Interpreter shipped along with AmigaDOS 2.0 and above.
Port allows messages to and from a program.
Commands and status through port. Automate complex text operations with Final Writer. Arbitrarily long sequence of events tied to one button or icon. Automate operations across multiple files or images. Tie programs from different authors together.