numbered. These LINE NUMBERS let the computer know which mode you are in and are very important. We'll explain them in detail later in the chapter. RTN - THE ACTION KEY! PLAYING WITH IMMEDIATE MODE The I RTN I key is the key that makes things happen. (RTN is short for Return.) In Immediate Type in this line: PRINT n"HELLO" Mode, it tells Aquarius· to exe· cute the command you just gave. In Programmed Mode. it tells Aquarius·· to store the statement you just typed, so that it can be executed when you are finished writing your program. IF YOU DON'T PRESS THE I RTN I KEY AFTER TYPING IN EVERY COM· ....., BYTHEWAY ....... The symbol n means SPACE. When you see this symbol. press the SPACE key.
We will only use this symbol when there is an impor· tant reason to include a space. COMMAND IN IMMEDIATE MODE MAND OR STATEMENT, NOTHING WILL HAPPEN. The I RTN I key also sends the cursor to the beginning of the next line, so you're ready to type your next command or state· ment. Now press the I RTN I key to enter the command. Did Aquarius print HELLO? Press I RTN I again to drop down another line. Then type this: PRINT 2 + 4 and press RTN. Did Aquarius print 6? Key[[] is also marked RETURN on the overlay, but this is another animal altogether. Don't confuse the two keys or you will end up confusing yourself. STATEMENT IN PROGRAMMED MODE