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data
transfers
on
input
buffers
and
signal
if
the
device
the
for
transfer
PIA
a
enabled
when
the
proper
*
Reset(RES)
The
active
Low
RES
logical
PIA
to
a
and
master
reset
a
as
se1e
*PIA
Chip
These
three
input
kr:
Uifvln
rn1~|a{-
an/4
PC
ma--
-t
and
nigh
e-2
transfers
then
are
lines
The
chip
select
*
Register
PIA
Select(RSO
The
two
register
the
These
PIA.
two
Registers
to
select
The
register
and
while
of
the
E
pulse
*
Request(IRQA
Interrupt
active
The
Low
Interrupt
either
the
directly
MPU
lines
drain(no
are
open
tied
lines
be
est
to
1.6
mA
to
curret
up
bits
that
rupt
flag
bit
is
associated
enable
four
interrupt
inhibit
to
particular
a
Servicing
interrupt
an
routine
that,on
a
control
registers
two
The
interrupt
flags
Peripheral
Data
Operation
these
lines
used
are
from
the
inactive
occur
condition
input
signal
to
has
been
enabled
conditioned,the
interrupt
of
the
interrupt
*
PIA
PERIPHERAL
INTERFACE
The
PIA
provides
interrupt/control
*
Section
A
Peripheral
Each
of
the
peripheraldata
input
output.
or
Direction
ing
Data
O
in
bit
of
A
a
peripheraldata
line
Operation,
the
data
directly
appears
Output
The
d a t a i n
programmed
to
are
will
High
cause
a
the
Data
Bus.
A
Low
data
is
transferred
has
been
selected.
of
data
the
to
and
address
line
is
used
to
This
line
Low.
zero
during
system
signals
used
to
are
Ha
m11c+-
Tr\v.1
Fnr
mu-.
be
ao"
lor
performed
under
the
must
be
stable
and
RS1)
lines
used
to
are
lines
in
used
are
particular
register
a
lines
chip
select
in
the
read
or
and
IRQB)
lines(IRQA
Request
interrupt
through
or
load
device)
in
wire
together
a
from
outside.
gagh
the
IRQ
can
cause
with
particular
a
bits
provided
are
interrupt
from
the
by
MPU
may
prioritized
basis,seqentially
in
each
PIA
for
cleared(zeroed)
are
of
the
corresponding
interrupt
inputs
as
the
edge
to
the
edge
sense
and
the
edge
sense
will
flag
input
pin.
LINES
8
bit
bi-directional
two
lines
for
interfacing
Data(PA'~PA7)
lines
can
This
is
accomplished
Register
bit
for
the
Data
Direction
to
act
aninput.
as
the
peripheral
on
the
corresponding
on
Register
will
A
be
logical
outputs.
A
the
corresponding
on
T3
the
line
state
PIA
on
the
the
from
MPU
to
the
R/W
A
High
on
The
bus.
PIA
output
the
enable
the
and
reset
all
register
be
used
can
as
a
power
operation.
select
the
CS
PIA.
devgce. Dat;
cc1c>/
of
the
-election
control
the
of
E
duration
for
the
of
select
the
various
with
internal
conjunction
that
is
to
be
should
be
for
stable
write
cycle.
and
IRQB)
priority
circuitry.
This
permits
all
.
QR_configuration
line
has
IRQ
two
line
Each
to
Low.
go
peripheral
interrupt
in
the
which
PIA
device.
peripheral
a
be
accomplished
reads
and
bits
interrupt
flag
result
of
as
a
data
register.
at
least
E
one
active
of
these
edge
network.
If
the
circuit
has
been
properly
be
set
the
next
on
data
bused
and
devices.
peripheral
to
be
programmed
to
setting
l
in
by
a
those
lines
which
are
Register
the
causes
During
MPU
Read
an
lines
programmed
lines.
MPU
Data
Bus
the
data
appear
on
l
written
into
data
line
while
enables
the
the
PIA
E
on
line
sets
up
buffers
are
present
pulse
E
are
bits
in
the
reset
on
and
CS
R/W
and
signals.
the
E
pulse.
inside
registers
Control
written
read.
or
the
duration
interrupt
act
to
These
interrupt
requ-
and
accept
internal
inter-
flag
line.
Also
be
used
may
software
by
a
the
tests
that
set.
are
MPU
Read
an
When
pulse
must
interrupt
interrupt
flag
active
transition
four
act
as
an
the
correspond-
be
to
outputs.
corresponding
Data
Peripheral
to
act
input
as
lines
that
the
register
O
results
in
a
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