Apple II manual Print Intruder Alert, Commands, Statement SYNTAX/FUNCTION Example Clear

For instance, suppose bit 1 of location 40963 is 0 when the door to Room X is closed, and 1 if the door is open. The following program will print "Intruder Alert" if the door is opened:

10	IF NOT (PEEK(40963) AND 2) THEN 10	This line will execute over and over until
		bit 1 (masked or selected by the 2)
		becomes a 1. When that happens, we go
		to line 20.
20	PRINT "INTRUDER ALERT"	Line 20 will output "INTRUDER
		ALERT."

However, we can replace statement 10 with a "WAIT" statement, which has exactly the same effect.

10 WAIT 40963,2	This line delays the execution of the
	next statement in the program until
	bit 1 of location A003 becomes 1. The
	WAIT is much faster than the equivalent
	IF statement and also takes less bytes
	of program storage.
The following is another useful way of using relational operators:
125 A=-(B>C)*B-(B<=C)*C	This statement will set the variable A
	to MAX(B,C) = the larger of the two
	variables B and C.

303 COMMANDS

A BASIC command may be entered when the cursor is displayed. This is called the "Command Level." Commands may be used as program statements. Certain commands, such as LIST, NEW, and LOAD

will terminate program execution when they finish. Each command may require one or more

arguments in addition to the command statement, as defined in the syntax/function description. An argument without parenthesis is required to be entered without parenthesis. Arguments contained within parenthesis are required to be entered with the shown parenthesis. Arguments within brackets are optional. Optional arguments, if included, must be entered with or without accompanying parenthesis, however shown.

STATEMENT	SYNTAX/FUNCTION	EXAMPLE
CLEAR	CLEAR	CLEAR
	Clears all program variables, resets "FOR"
	and "GOSUB" state, and restores data.
STATEMENT	SYNTAX/FUNCTION	EXAMPLE
CONT	CONT	CONT
	Continues program execution after the F1
	key or a STOP or INPUT statement termi-
	nates execution. You cannot continue after
	any error, after modifying your program, or
	before your program has been run. One of
	the main purposes of CONT is debugging.
	Suppose at some point after running your
	program, nothing is printed. This may be
	because your program is performing some
	time consuming calculation, but it may be
	because you have fallen into an "infinite
	loop." An infinite loop is a series of BASIC
	statements from which there is no excape.
	BASIC will keep executing the series of
	statements over and over; until you inter-
	vene or until power to the AIM 65 is
	turned off. If you suspect your program
	is in an infinite loop, press F1 until the
	BREAK message is displayed. The line
	number of the statement BASIC was
	executing will be displayed. After BASIC
	has displayed the cursor, you can use
	PRINT to type out some of the values of
	your variables.	After examining these