of Microprocessors

17
DigitalHardware
At this point, we are ready to start discussing actual implementation and use
of some of the digital sound synthesis and modification techniques that have
been described. There is, however, a natural division between hardware and
software implementation techniques. Either can perform any of the functions
that have been studied. A hardware approach performs the data movement
and calculations considerably faster than software. In fact, the usual goal of
hardware implementation is real-time operation. Software, on the other
hand, is cheaper, easier, and more flexible but much slower. Finally, the $5
MOS microprocessor and high-speed bipolar microprocessors make possible a
third category that behaves in a system like a hardware implementation but
is designed, and for the most parr, built like a software implementation.
Hardware implementation and real-time operation seem to be of
greatest interest to most people at this time. Digital synthesis hardware can
be integrated into an overall computer-controlled system in several ways,
however. At the lowest level, one can build modules that on the outside act
just like analog modules but offer greater precision, more flexibility, and
perform functions impossible to do with analog hardware. Along the same
lines, the voice-per-board method of system organization can be done entirely
with digital hardware and with the same advantages. One may define
and construct a modular digital synthesizer that conceptually acts like a
modular voltage-controlled synthesizer but is all digital, including the
signal-routing system. It is also practical to consider an actual programmable
"computer" specialized for ultra-high-speed execution of synthesis algorithms
in an effort to combine the flexibility of software with the speed
necessary for real-time operation. Special-purpose "black boxes" that perform
cerrain useful but time-consuming operations such as the FFT can also be
added as a peripheral to general-purpose computers in order to enhance the
speed of software-based synthesis.
U nforrunately, a complete discussion of all of these options is well
beyond the scope of this chapter. However, those suitable for implementation
by individuals will be described in detail, while the others will only be
surveyed.
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