Overall Functional Block Diagrams
Overall functional block diagrams will show the
functional areas of the computer and the supporting
functions, such as power, cooling, and control of the
computer. They will also show the types of signals
exchanged between the functional areas and the
supporting functions and the direction of signal flow.
Figure 2-1 is an example of an overall functional block
diagram of a computer.
Overall functional block diagrams are very useful
when you perform corrective maintenance. After you
have identified and elaborated on a problem, you can
use the overall block diagram for the “listing of
probable faulty functions.” This will help you in your
next step in the troubleshooting process— “localizing
the faulty function.” The overall functional block
diagram can help you stay in the right area when
troubleshooting.
Individual Functional Block Diagrams
Once an overall description has been presented, the
technical manual will give a general description of each
functional area separately. These will include the major
functional areas (CPU, I/O, and memory); the
supporting functional areas (power supply and any
special cooling requirements); and control of the
computer (maintenance console/panel or display
control unit and remote console/panel). When each
functional area is described individually, an
accompanying functional block diagram of that area
will follow. Individual functional block diagrams can
help you in your troubleshooting once you have
“localized the faulty function.” They provide a more
detailed analysis of how that specific area of the
computer operates. See figure 2-2 as an example of an
individual functional block diagram of a CPU.
FUNCTIONAL LAYOUTS OF
COMPUTERS
Functional layouts will show the major functional
areas of the computer—CPU, I/O, and memory. Figure
2-3 is an example of an individual functional layout for
a basic single cabinet configuration.
Systems that use a multiple configuration with
more than one computer will also be depicted using an
Figure 2-1.—Example of an overall functional block diagram
2-2
