Z89340 Datasheet, PDF (18/30 Pages) Zilog, Inc. – Digital Wavetable Engine

Z89340
Digital Wavetable Engine
FUNCTIONAL DESCRIPTION (Continued)
Tape Loop Oscillator
The Tape Loop Oscillator takes its input from an input reg-
ister, an effects channel, or a submix register. It then reads
a sample from wave RAM, and writes the scaled input val-
ue plus the scaled and filtered sample from wave RAM
back to the same location in wave RAM. It behaves very
much like a tape recorder with a loop of tape, hence the
name “Tape Loop.” Echo and single-delay reverberation
can be accomplished with the Tape Loop Oscillator. The
amount of delay is set with the Wave Loop Length regis-
ters, and can be more than a second if you are willing to
dedicate the necessary RAM. This oscillator can also be
used to transfer input from a ADC that is connected to one
of the input registers. In this way the input can be buffered
in RAM for later use by the CPU host, or processing can
be done by the Z89340 before sending the signal to a ste-
reo submix register pair or one or more output channels.
The Tape Loop Oscillator can also perform the function of
the comb filter component of reverb algorithms (Figure
12).
Figure 12. The Tape Loop Oscillator Address Map
1-18
PRELIMINARY
DS96DSP0201