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Glossary-8
8XC196NP, 80C196NU USER’S MANUAL
special-purpose memory A partition of memory used for storing the interrupt
vectors, PTS vectors, chip configuration bytes, and
several reserved locations.
standard interrupt Any maskable interrupt that is assigned to the
interrupt controller for processing by an interrupt
service routine.
state time (or state) The basic time unit of the device; the combined
period of the two internal timing signals, PH1 and
PH2. (The internal clock generator produces PH1 and
PH2 by halving the frequency of the signal on
XTAL1. The rising edges of the active-high PH1 and
PH2 signals generate CLKOUT, the output of the
internal clock generator.) Because the device can
operate at many frequencies, this manual defines time
requirements in terms of state times rather than in
specific units of time.
t Lowercase “t” represents the period of the internal
clock. For the NP, t is the reciprocal of F
XTAL1
(1/F
XTAL1
, where F
XTAL1
is the input frequency on
XTAL1). For the 80C196NU, which employs a
phased-lock loop with clock multiplier circuitry, t is
the reciprocal of either F
XTAL1
, 2F
XTAL1
, or 4F
XTAL1
.
The multiplier depends on the clock mode, which is
controlled by the PLLEN1 and PLLEN2 input pins.
(Figure 2-4 on page 2-8 illustrates the clock circuitry
of the 80C196NU.)
UART Universal asynchronous receiver and transmitter. A
part of the serial I/O port.
WDT See watchdog timer.
word Any 16-bit unit of data.
WORD An unsigned, 16-bit variable with values from 0
through 2
16
–1.
zero extension A method for converting data to a larger format by
filling the upper bit positions with zeros.