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and more about Sharp
PC-1500
at http://www.PC-1500.info
2-3. Functions
14
2-3-1. Timer
The
tinttcr
is
a
9-bit
polynorninal
counter.
·rhc
counter
value
can
be
set
by
the AMO or
AM
I
instr
uction
of
the
C
P
U.
S
hown
in ..
POLI NOMINAI. CO
UN'rE
R
..
is
the
list
o
f
hcxadccin1
al
data of
counter \vith dccin1al count
nurnbcr.
TI1
e
ti1ner
operates continuously
at
alJ
tirncs.
\\ihcn
the
counter
va lue
reaches
11
=-i-:H.
it
issues
interrupt request
to
the
CPU.
If
IE
(lntcnupt Enable)
flag
is
active
at that
poim.
the
Cl)U
j
un1ps
to the
tin1cr interrupt
processing
routine
\vhosc
high
order
byte
address
is
represe
nted
by
the
contents
of
the address F
FFAH
a
nd
low
order
by1c
address
by
the
contents of
the
address
FFFl3H
.
TI1c
timer
has
10
be
set
to
OOOH
whe
n it
is
not
used.
Since
it
counts
in
synchroni1;·
1 1
ion \Vith
the
clock
<l>F.
each
one
cycle
or <J>
F
incr~ntcnts
the
counter
one
step.
L . _ _
D
_
iv
_
id
_
,e
_r
_
_,I
-
<I>
F
\ Vhen
chc
4rvtH
z
crystal
oscillator
is
in
connection.
the
tin1er
is
incren1ented
at
C(lch
32µ
scc.
because <PF is
3
I
.25k
Hz.
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not
sale
this PDF!!!
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