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Atari 2600 Sound Values

--------------------------ATARI 2600 VCS PRECISE SOUND VALUES-------------------
------------------------------AND DISTORTION BREAKDOWN--------------------------
--------------------------------------------------------------------------------
---------------------------------BY GLENN SAUNDERS------------------------------
-------------------------------LAST REVISION  4/2/97----------------------------
--------------------------------------------------------------------------------

The Atari 2600 (and the Atari 8-bit) produces tones based on polynomial
counters.  Because of this, a great many of the notes are "out of tune" 
(although it's a lot worse on the 2600 than the 8-bit, which is why 7800
Ballblazer has POKEY on board, for instance.) N ot only that, but there
are some intervals between notes in all of the distortions at the upper-
register which will make slim pickings up there, and some of the notes are
spread between two different distortions like a jigsaw puzzle.  These
charts were created for programmers to consult so that they can compose
music that only uses notes that are in tune.  To my ears, this means no
more than 10 "cents" off perfect pitch (relative to other notes). 

One important thing I have to add is octave values, but I don't have a
keyboard and no way of knowing what "C1" is so this will have to wait
unless someone else would like to revise it. 

The process by which music can be composed is tricky.  It will require you
to build additional charts off this one that group notes based on how "in
tune"  they are in relation to eachother.  For instance, you could sort
out all the notes that are between +40 and +50 cents out of tune.  Then
you will figure out which group of notes provides you with the largest
variety of notes.  Then you will attempt to take your standard notation
and transpose it as best you can to conform it to the available notes
without resulting in "unattainable" notes.  The only analogy I can think
of is a DULCIMER, which is fretted so that only the major diatonic scale
can be played, which limits you to only one key.  You can't play a
chromatic scale with a dulcimer, and you aren't likely to be able to play
many well-tempered notes close to eachother on the 2600 either. 

Another thing that makes it tricky is the crossover between X# -50 and X
+50.  Just be aware that the two notes in this example are VERY close in
pitch when sorting and building new charts.  If you do build a chart that
crosses over like this, you'll probably have to convert one to the other
in order to make workable music. 

Music that will translate well to the 2600 will probably use lots of
octaves and fifths, since there are plenty of those (in tune) in all
pitches. 

REVISION HISTORY

4-1-97 First revision.  There is a good chance some of the notes may be off due
       to the chromatic tuner returning the value of overtones and not the
       fundemental.  I did the best I could with it.  There is some room for
       improvement as well as picking some more notes out of the bassy "rumble"
       areas.


--Glenn Saunders <krishna@primenet.com>

-------------------------------------------------------------------------------
CHART KEY----------------------------------------------------------------------

COLUMNS=Distortion value (decimal) and variation from perfect pitch in CENTs.
        Values containing ? = unknown.  Values qualified with an additional ?
	means best-guess.

ROWS=Note values (decimal).

===========================THE 2600 NOTE CHART=================================

		  
 NOTE       1       1 CENT  2          2 CENT     3          3 CENT     
 ---------- ------- ------- ---------- ---------- ---------- ---------- 
 00         C       -5      C#         -50        C#         -50        
 01         C       -5      C#         -50?       C#         -50?       
 02         F       -5      F#         -50?       F#         -50?       
 03         C       0       C#         -50?       C#         -50?       
 04         G#      +11     B          -50?       B          -50?       
 05         F       -5      D#         ?          D#         ?          
 06         D       +30     C#         -50?       C#         -50?       
 07         C       0       B?         ?          B          ?          
 08         A#      -8      C#         -50?       C#         -50?       
 09         G#      +10     MED RUMBLE            G#         +40? 
 10         F#      +50     RUMBLE                G          0?         
 11         F       -5      RUMBLE                F          0?         
 12         E       -50     RUMBLE                E          -40?       
 13         D       +30     RUMBLE                D          +30?       
 14         C#      +10     RUMBLE                C#         +50?       
 15         C       0       RUMBLE                C#         -50?       
 16         B       -10     RUMBLE                B          +25?       
 17         A#      -10     RUMBLE                A#         +10?       
 18         A       0       RUMBLE                A          +30        
 19         G#      +10     RUMBLE                G#         +40        
 20         G       +30     RUMBLE                G          +50        
 21         F#      +50     RUMBLE                G          -20        
 22         F#      -30     RUMBLE                F#         0          
 23         F       -5      RUMBLE                F          +20?       
 24         E       +30     RUMBLE                F          -50?       
 25         E       -50     RUMBLE                E          -30?       
 26         D#      -10     RUMBLE                D#         -20?       
 27         D       +35     RUMBLE                D          +30        
 28         D       -32     RUMBLE                D          0?         
 29         C#      +10     RUMBLE                C#         0?         
 30         C#      -50     LOW RUMBLE            C#         -30?       
 31         C1?     0       C#?        -50?       C#         -50?       


 NOTE       4 AND 5    4&5 CENTS  6 AND 10   6&10 CENTS  7 AND 9    8          
 ---------- ---------- ---------- ---------- ---------- ---------- ---------- 
 00         SILENT                B          +40        SAME AS 6  WHITE NOISE 
 01         B          ?          B          +40        DIFF DIST  HIGH       
 02         E          ?          E          +40                   HIGH       
 03         B          ?          B          +40                   HIGH       
 04         G          ?          G#         -50                   HIGH       
 05         E          ?          E          +40                   HIGH       
 06         C#         ?          D          -30                   HIGH       
 07         B          ?          B          +40                   HIGH       
 08         A          ?          A          +40                   HIGH       
 09         G          ?          G#         +40                   HIGH       
 10         F          +50        F#         -10                   MED        
 11         E          -20        E          +40                   MED        
 12         D          0          D#         0?                    MED        
 13         C#         +20        D          -40                   MED        
 14         C          -5         C#         -40?                  MED        
 15         B          -15        B          +40?                  MED        
 16         A#         -20        A#         +50?                  MED        
 17         A          -20        A          +50?                  MED        
 18         G#         -15        G#         +50                   MED        
 19         G          0          G#         -50?                  LOW        
 20         F#         +15        G          -40?                  LOW        
 21         F          +40        F#         -20?                  LOW        
 22         F          -50        F          0?                    LOW        
 23         E          -20        E          +30                   LOW        
 24         D#         +15        E          -50?                  LOW        
 25         D          +50        D#         -20?                  LOW        
 26         D          -20        D          +30?                  LOW        
 27         C#         +20        D          0?                    LOW        
 28         C#         -50        C#         +30                   LOW        
 29         C          0          C#         -20?                  LOW        
 30         B          +50        B          0?                    LOW        
 31         B          -15        B          +40                   LOW        


 NOTE       12 AND 13  12&13 CNTS 14         14 CENT    15         
 ---------- ---------- ---------- ---------- ---------- ---------- 
 00         A          -20?       E          +40        SAME AS 14 
 01         E          -40?       E          +40        DIFF DIST  
 02         A          -20        A          +40                   
 03         E          -10?       E          +40                   
 04         C          0?         C#         -50                   
 05         A          -40        A          +40                   
 06         F#         +10        G          -50?                  
 07         E          -20        E          +40                   
 08         D          -20        D          +50?                  
 09         C          0          C#         -50                   
 10         A#         +30        B          0?                    
 11         A          -20        A          0?                    
 12         G          +50        G#         0?                    
 13         F#         +20        G          -20                   
 14         F          0?         F          +20?                  
 15         E          -20        MED BUZZ                         
 16         D#         -20        BUZZ                             
 17         D          -20        BUZZ                             
 18         C#         -15        BUZZ                             
 19         C          0          BUZZ                             
 20         B          +15        BUZZ                             
 21         A#         +32        BUZZ                             
 22         A#         -50        BUZZ                             
 23         A          -20        BUZZ                             
 24         G#         +10        BUZZ                             
 25         G          +50        BUZZ                             
 26         G          -25        BUZZ                             
 27         F#         +15        BUZZ                             
 28         F#         -50        BUZZ                             
 29         F          0          BUZZ                             
 30         E          +50        BUZZ                             
 31         E          -20        LOW BUZZ                         


ATARI 2600 VCS DISTORTION DESCRIPTIONS (XX & YY = exactly the same notes&dist.)
--------------------------------------

DECIMAL
DISTORTION
VALUE		WHAT IT SOUNDS LIKE
----------	---------------------
00 & 11 	TOTALLY SILENT
01		Buzzy tones
02		Carries distortion 1 downward into a rumble.
03		Flangy wavering tones, like a UFO
04 & 05		Pure tones
06 & 10		Inbetween pure tone and buzzy tones (Adventure death uses this)
			Maybe filters off the highs here
07 & 09		Reedy tones, much brighter, down to Enduro car rumble
08		White noise/explosions/lightning, jet/spacecraft engine
12 & 13		Pure tones, goes much lower in pitch than 04 & 05.
14		Electronic tones, mostly lows, extends to rumble.
15		Electronic tones, mostly highs, extends to rumble.
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