YES/NO Test

Using the YES/NO Test

The Y/N test gives you an easy way to let the user control the program by answering yes or not to a question. Unlike the tests discussed previously in this chapter, the Y/N test does not compare any numeric values in the program.

The YES/NO Test

When you press [ TESTS ], you can the Y/N test into your program.
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{ Y/N } - Defines the [ F1 ] key as YES and the [ F2 ] key as NO and halts the program. This lets the user of your program responde to an alpha message you have placed in the display.

If you press { NO } in response to the Y/N test, the first instruction following the test is skipped. If you press { YES } in response to the Y/N test, execution continues in normal sequential order.

Although you could create a yes/no menu using the DFN instruction, the Y/N test has the following advantages whenever you want a program to pose a yes/no question.

You do not have to include { YES } and { NO } function key definitions.
You do not have to include a HLT instruction in the program.
You do not have to clear any function key definitions. (The calculator clears the definitions automatically.)

Example

The following program creates a loop that calculates the square roots of a sequence of numbers beginning with 1. The program uses a Y/N test to ask if you want to sum each result to data register B.

PC =	Program Mnemonics	Comments
0000	0 STO A STO B	Initializes A and B
0005	LBL AA	Begins loop
0008	INC A	Increments count
0010	RCL A	Gets current count
0012	SQR	Calculates square root
0013	PAU	Displays square root
0014	`SUM TO B?`	Creates message
0023	Y/N	YES/NO test
0024	ST+ B	{ YES } - Sum to B
0026	GTL AA	Repeats loop

Running the Example

Run the program and sum the values of the first and third square roots.

Procedure	Press	Display
Start the program	[ RUN ] { PGM }
Sum 1st number	{ YES }
Don't sum 2nd number	{ NO }
Sum 3rd number	{ YES }
Check the sum	[ RCL ] B
Clear function keys	[ 2nd ] [ F:CLR ]