NOISE -- Precise control of the beeper for music & sound effects
SIZE: 299 bytes.

(“MUSIC” program = 712 bytes;
"TUNEUP" program = 340 bytes;
“MARYLAMB” = 62 byte string saved in a DATA file;
“PHASER” = 360 byte string saved in a DATA file;
“WTELL” = 1824 byte string saved in a DATA file)

NOISE is similar to the NOISE statement that HP put into the HP-75
I/O ROM and then didn’t mention in the owner’s manual. Given a
string containing encoded frequencies and durations, NOISE plays it
as music (or noise). Does not use the operating system’s BEEP
subroutines, but drives the beeper directly, resulting in a much
wider frequency range than the BEEP function has. Timing is also
much more precise. Comes with a BASIC program called MUSIC that
allows you to write music on the keyboard, listen to it, save it in
a file, and play back files thus saved. Three sample music files are
available on card, tape or disc: MARYLAMB (Mary Had a Little Lamb),
PHASER (spine-tingling red-alert type of sound), and WTELL (about
two minutes of the William Tell Overture).

Attempting to play stereo music on two HP-71's using NOISE only
works if their clock speeds are identical, which never happens.
To compensate, run the TUNEUP program, which modifies the NOISE
lexfile to match the actual clock speed of the host HP-71, thus
enabling two HP-71's with different clock speeds to play
synchronized music.


*** NOISE ***
(31898) File Header
(3190E) 5F/01 NOISE
(31B12) Next File Header