Each time the program executes a GOSUB, the line number and position in the program line are saved in a special area called the "stack," which takes up 256 bytes of your memory. This limits the amount of data that can be stored in the stack. Therefore, the number of subroutine return addresses that can be stored is limited, and care should be taken to make sure every GOSUB hits the corresponding RETURN, or else you'll run out of memory even though you have plenty of bytes free.

GOTO

Action: This statement allows the BASIC program to execute lines out of numerical order. The word GOTO followed by a number will make the program jump to the line with that number. GOTO NOT followed by a number equals GOTO 0. It must have the line number after the word GOTO.

It is possible to create loops with GOTO that will never end. The simplest example of this is a line that GOes TO itself, like 10 GOTO 10. These loops can be stopped using the <RUN/STOP> key on the keyboard.

   GOTO 100
   10 GO TO 50
   20 GOTO 999

IF...THEN...

Action: This is the statement that gives BASIC most of its "intelligence," the ability to evaluate conditions and take different actions depending on the outcome.