This is the Doc file for the AMI S50240 Top Octave Synthesizer IC.
Forrest M. Mims, Engineer's Notebook (I) 1980 Edition, Page 46.

*********
This chips outputs NEED to be either buffered with an active follower gate
(CMOS) or current limited by 100K Ohm resistors if more than one output
is to be played at once to protect the outputs!!
*********

It requires a clock source of 2.00024 MHz. It has 12 separate moduli
dividers to produce the 12 tone equally tempered scale by frequency
division of a square wave clock. The notes and divisors for its outputs
are thus:

C8   C8#  D8   D8#  E8   F8   F8#  G8   G8#  A8   A8#  B8   C9  : Notes
478  451  426  402  379  358  338  319  301  284  268  253  239 : Divisors

And these result in frequencies of:
--
IC Pin: Divisor: Note: Frequency:    Should be:
16      478      C8    4184.6025     4186.0088
4       451      C8#   4435.1220     4434.9219
5       426      D8    4695.3991     4698.6361
6       402      D8#   4975.7214     4978.0316
7       379      E8    5277.6781     5274.0408
8       358      F8    5587.2626     5587.6516
9       338      F8#   5917.8698     5919.9107
10      319      G8    6270.3448     6271.9269
11      301      G8#   6645.3156     6644.8751
12      284      A8    7043.0986     7040       <-- If A4 = 440 Hz
13      268      A8#   7463.5821     7458.6202
14      253      B8    7906.0870     7902.1329
15      239      C9    8369.2050     8372.0182
--
1   SUPPLY  +11 -> +16 VDC
2   CLOCK
3   GND
--

Copyright (c)1997 by Richard Steven Walz for Limited Public Domain
Non-Commercial Use Only - All Commercial Rights retained by the Author.
--
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