Page 155 - Electrical Engineering Dictionary

complex amplitude transmittance One of the benefits of a CISC is that the
transmittance of the complex amplitude, code tends to be very compact. When mem-
square root of the intensity transmission. ory was an expensive commodity, this was a
substantial benefit. Today, speed of execu-
complex beam parameter See beam tion rather than compactness of code is the
parameter. dominant force.
See also microprogramming, reduced
complex envelope a low-pass complex instruction set computer processor.
valued signal used to represent a real band-
pass signal. The complex envelope is ob- complex number a number consisting
tained from the analytic signal with center of a real part and an imaginary part, usually
frequency ω c by multiplying the analytic sig- expressed in the form a +bi, where the “i”is
nal by e −jω c t . used to distinguish that b represents the com-
plex part of the number. i is mathematically
complex exponential signal a signal of defined as the positive root of −1.
the form x(t) = C exp jωt, where C is a
constant and ω is the frequency in radians complex power a complex number that
per second. represents electric power flow for an AC cir-
cuit. When expressed in rectangular form its
complex frequency a complex number real part is average power P in watts and its
used to characterize exponential and damped imaginary part is reactive power Q in reac-
sinusoidal motion in the same way that an tive volt-amperes. When expressed in polar
ordinary frequency characterizes simple har- form its magnitude is apparent power S in
monic motion; designated by the constant s volt-amperes and its angle is the power fac-
corresponding to a motion whose amplitude tor angle (the same angle as the impedance
st
is given by Ae , where A is a constant and t angle for a passive load). See also apparent
is time, and s = σ + jω where σ is the real power.
part of s and ω is the imaginary part of s. ω
is also known as the real angular frequency. complex process (system) term used
rather colloquially to denote controlled pro-
complex instruction set computer (CISC) cess(controlsystem)possessingsuchcharac-
a processor with a large quantity of instruc- teristic features which, separately or jointly,
tions, some of which may be quite compli- allow to treat this process (system) as a com-
cated, as well as a large quantity of different plex entity; the features worth consideration
addressing modes, instruction and data for- are:
mats, and other attributes. The designation 1. The process is large in a physical sense
was put forth to distinguish CPUs such as — it occupies large space and there are large
those in the Motorola M68000 family and the distances among its different elements,
Intel Pentium from another approach to CPU 2. The model of the process is compli-
design that emphasized a simplified instruc- cated and involves many variables, in partic-
tion set with fewer but possibly faster exe- ular control inputs,
cuting instructions, called RISC processors. 3. The process is composed of several in-
One CISC processor, the Digital VAX, has teracting subprocesses and there are identifi-
over 300 instructions, 16 addressing modes, ablelocalobjectivesandlocalsetsofdecision
and its instruction formats may take up 1 to variables,
51 bytes. 4. The control problem is seen as compli-
A CISC processor usually has a relatively cated due to the nature of the control objec-
complicated control unit. Most CISC pro- tives and the way by which free inputs are
cessors are microprogrammed. formed and influence the controlled process

c
2000 by CRC Press LLC