of Microprocessors

632
MUSICAL ApPLICATIONS OF MICROPROCESSORS
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12356791011 21 30 41 ~
HARMONIC NUMBER
61 71 79
(E)
Fig. 17-24. Effect of symmetry logic on waveform and harmonic spectrum
(cont.). (E) Waveform with odd symmetry followed by even symmetry
and spectrum.
8-bit prescaler counter built with 7415161 counters. The "15" version is
necessary because a timing anomaly of the standard 74161 prevenrs operation
at high clock frequencies. An eight-input multiplexor (74151) selects one of
the eight divided outputs under the control of three frequency control bits.
The multiplexor output is strobed by a D-type flip-flop to suppress glitches
when the frequency control register is changed.
The prescaler output clocks both the accumulator and the postdivider.
The latter is enabled to count only when the adder in the accumulator divider
generates a carry output. Note that the frequency and mode control registers