Commodore Plus 4 - Page 186

174 Some Programming Techniques
Random Numbers BASIC has a built-in random number function that returns
a floating point number between 0 and 1. When called with a negative argument,
the RND function reseeds the random number generator with the value specified
and returns the first value from this seed. When called with a zero argument, the
RND function reseeds the random number generator from a hardware clock and
returns the first value from this seed. When called with a positive argument, the
next value in the random sequence is returned. To have a different random
number sequence every time the program is run, call RND at zero first, then at 1
(or any positive number) thereafter. To have the same sequence each time, call
RND at a constant negative seed value first, then at 1 (or any positive number)
thereafter.
When a random floating point number between L and H is needed, use
(H-L)*RND(1)+L
When a random integer between L% and H% (inclusive) is needed, use
INT((H%-L%+1)*RND(1)+L%)
Programming Sound and Music
The computer has two voices that can play music and a voice setting that can
create noise. Only two commands, VOL and SOUND, are required to play music
and sound effects.
The VOL Command
The VOL command sets the volume level for tones played by the SOUND
command. The volume level can be from 0 (off) to 8 (highest volume). You must
be sure that the volume selector on your TV or monitor is turned up. The level of
volume set by the VOL command is relative to other VOL settings. The absolute
sound level is set by the volume selector on your TV or monitor.
The volume level remains at the last level set at the end of a program. If you do
not turn the volume off at the end of the program or reset its value, the next
SOUND command plays at the volume last set, even if the next SOUND
command is in a different program.
You must execute a VOL command before the SOUND command, or you will
not be able to hear any sound.
The SOUND Command
The SOUND command selects the tone to be played. The SOUND command has
three parameters: