Commodore Plus 4 - Page 109

BASIC Version 3.8 Commands, Functions, and System Variables 97
The volume set by the VOL command is relative only to other VOL com
mands. You can make one sound louder or quieter than another by changing the
VOL setting in between. The overall volume is controlled by your monitor or TV.
Example: VOL 2 Sets a low volume
WAIT Abbr. wA
WAIT location, AND value, XOR value
Pauses the execution of the BASIC program until the value of the specified bits
in the given memory location equals a designated value.
Parameters: memory address, ANDed value to be checked, XORed value
1. The memory address is the location whose contents are to be checked.
2. The computer ANDs this value, which must be between 0 and 255, to the
value in the memory location. The memory location is repeatedly checked until
the operation yields a value that is not 0. When this happens, the program
continues with the command following WAIT.
3. This parameter is optional. If it is present, this value, which must be between
0 and 255, is XORed with the memory location contents before the ANDing takes
place. In other words, this parameter can be used to invert the comparison bits.
The location checked by a WAIT command must be changed by some external
event, such as a button on the tape recorder being pressed (see Chapter 6).
Otherwise, this command results in an infinite loop that can be exited only with
the reset button. Should this occur, remember to hold down the RUN/ STOP key
when pressing the reset button if you want to keep your program intact. Exit the
monitor by typing X and RETURN.
WHILE Abbr. wH
Sets a condition for the continuation of a DO... LOOP. A WHILE clause in a
DO loop makes the loop execute as long as the condition is met. See DO.