Filter
Top Products
KEY
CXNCEP'IS
The
Interface
Processor
provides
a
process
addressing
environment
within
the
432 system which
supports
the
operation
of
the
I/O
controller
in
the
432
system.
This
environment
is
embodied
as
a
set
of
system
objects
that
·"are
used
and
manipulated
by
the
IP.
At any
t~e,
the
I/O
controller
is
represented
in
432
memory
by
IP
process
obj
ects
am
associated
context
obj
ects.
Like
a
GOP,
the
IP
itself
is
represented
by a
processor
object.
Representing
the
IP
and
its
controlling
software
like
this
creates
an
execution
environment
that
is
analogous
to
the
environment
of
a
process
running
on a
GOP.
This
environment
provides
a
standard
framework
for
addressing,
protection
and
conmunication
within
the
432
system.
Like
a
GOP,
an
IP
suworts
multiple
process
environments.
The
I/O
controller
selects
the
environment
in
which a
function
is
to
be
executed.
This
permits,
for
example,
the
establishment
of
separate
environments
corresponding
to
individual
device
processes
in
the
Peripheral
Subsystem.
If
an
error
occurs
while
the
IP
controller
is
executing
a
function
on
behalf
of
one
device
task
of
the
I/O
controller,
that
error
is
confined
to
the
associated
process,
and
processes
associated
with
other
device
tasks
are
not
affected.
Every
transfer
of
data
between
the
432
system
and a
Peripheral
Subsystem
is
performed
via
an
IP
window. A window
defines
a
correspondence,
or
mapping, between a
subrange
of
consecutive
Peripheral
Subsystem
memory
addresses
(within
the
range
of
addresses
occupied
by
the
IP) and
an
object
of
system
type
data
segment
in
432
system
memory
(see
figure
1-5).
When
an
agent
in
the
Peripheral
Subsystem
(e.
g • ,
the
IP
controller)
reads
a windowed
address,
it
obtains
data
from
the
associated
object;
writing
into
a windowed
address
transfers
data
from
the
Peripheral
Subsystem
to
the
windowed
object.
The
action
of
the
IP,
in
mapping
the
Peripheral
Subsystem
address
to
the
system
object,
is
transparent
to
the
agent
making
the
reference.
As
far
as
it
is
concerned,
it
is
simply
reading
or
writing
menory.
1-11