Thus, all of the characteristics listed in Table 16.4 fall along a spectrum of design
strategies. In general, a design that falls toward the left end of the spectrum is
intended to optimize the performance of the control unit. Designs toward the
right end are more concerned with optimizing the process of microprogramming.
Indeed, microinstruction sets near the right end of the spectrum look very much
like machine instruction sets. A good example of this is the LSI-11 design, described
later in this section.Typically, when the objective is simply to implement a
control unit, the design will be near the left end of the spectrum.The IBM 3033 design,
discussed presently, is in this category. As we shall discuss later, some systems
permit a variety of users to construct different microprograms using the same microinstruction
facility. In the latter cases, the design is likely to fall near the right
end of the spectrum.