of Microprocessors

SIGNAL ROUTING 273
COMPUTER
Fig. 8-1. Type 1 manually patched system
Manually Patched Computer-Controlled System
As mentioned previously, the manually patched system is really nothing
more than a box of DACs added to an otherwise conventional synthesizer
as shown in Fig. 8-1. Since use ofstandard off-the-shelf components (including
the computer system) is one of the attractions of this organization, most
comments will be made with this in mind. This, of course, should not
discourage home construction of the needed modules (which can easily cost
one-quarter as much as purchased modules), but most hobbyists would probably
be interested in one of the more sophisticated organizations.
The synthesizer is obviously an important part of the system. In many
cases, one must make do with an existing available sy~thesizer. If a synthesizer
or a collection of modules is being purchased for the system, however,
attention to a few key characteristics will insure success with a minimum of
effort.
Synthesizer Requirements
Overall quality of the modules should be moderate to high. One should
not accept poorer performance from a synthesizer that is to be computer
controlled than would be acceptable for manual control. In fact, the computer
is usually much less able to correct for deficiencies in the analog
modules than a human player is. For example, a person using a ribbon
controller or other proportional control device hears the sounds as they are