Msg: 68 *Conference*

06-09-91 13:17:17

From: FRANK MCJUNKINS

To : CHARLES STEVENS

Subj: 102 TONES

Thanks for the 'basic' info, Charles.  I didn't get the end of you message 
though.   In the meanwhile, I'm getting a little soured by the lack of response
to inquiries about this machine.  In a way its good, as its forced me to spend
a whole lot more time than I anticipated learning the machine and its in's and
outs.  I discovered the answer to my own question which is answered here for
anyone else who wants to make the 102 create a specific tone frequency OTHER
than the musical notes: Fa = Desired audio tone.   Fs=SOUND number.  4915200
(Clock xtal freq.) Formula is:  4915200/Fa=N    N/2=Fs Example.  You want to
make the machine create a 1000 cycle (hertz) tone. 4915200/1000=4915.2
4915.2/2=2457.6    SOUND=2457.6 The stability will depend on the actual crystal
frequency and the ambient temperature of the machine.  I found the tone that
results when I use this formula is within a few cycles of what I really want,
so if your use is critical, you may need to play with the numbers a bit to
compensate for the crystal being off frequency, and also remember that the
temperature of the computer will affect the crystal frequency and thus the 
resulting SOUND number.   Now the next project is to discover where I can get
the actual audio frequency output from the machine, and find a way to make a
sine wave out of the apparent square wave audio tone that the SOUND number
creates.