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CBJECl'S
AND
OPERATORS
2-
2.
CBJECl'
ADDRESSING
AND
GLCBAL
SIDRAGE
MANAGEMENT
Object
addressing
on
the
IP
follows
the
same
three
level
sequence
as
on a
GOP.
The
steps
taken
to
address
an
object
are:
1.
Given an
access
descriptor,
a
processor
uses
the
directory
index
field
to
index
the
object
table
directory
and
gain
a
storage
descr
iptor
for
the
o~ect
table
which
contains
an
object
reference
for
the
desir
#
object.
2.
With
the
storage
descriptor
for
the
object
table
and
the
segment
index
field
of
the
access
descriptor,
the
processor
locates
a
storage
descriptor
for
the
requested
object.
3.
The
storage
descriptor
for
the
object
contains
the
base
and
length
information
required
to
locate
the
object
in
432
:mennry.
An
IP
can
he
directed
to
manipulate
objects
in
432 memory,
just
as
other
432
processors,
hut
lacks
any
facility
to
create
objects.
All
original
objects
used
by
an
IP
rust
be
predefined
and
loaded
into
432
memory
at
system
initialization
time.
Additional
objects,
which
may
be
required,
must
be
created
by a
GOP
process
(e.g.
the
storage
manager) •
A 432
operating
system
type
manager
might
maintain
a
template
for
a
prototype
IP
process.
When
i t
received
a
request
for
a
new
IP
process
from
the
I/O
oontroller
the
GOP
would
build
one
using
the
prototype
and
then
return
it
via
the
standard
communication
port
mechanism.
2-
3.
CBJECl'S
FOR
PROGRAM
ENVIRCNMENTS
The
IP
suW'rts
the
same program environment
hierarchy
(process,
context,
domain)
as
a
GOP
but
implements
each
level
differently.
The
IP
does
not
require
that
a domain
object
be
implemented
but
the
oontext
object
contains
a
slot
for
an
access
descriptor
for
a domain
object
should
one
be
required.
When
implemented,
IP
domains
do
not
contain
instruction
segments
(since
the
IP
does
not
fetch
instructions)
or
operand
stack
segments. The
danain
may
be
used
to
store
same
static
information
which
may
be
required
by
a
process.
An
IP
context
is
a
refinement
of
an
IP
process
object.
Each
IP
process
is
bound
to
a
single
context
for
the
lifet~
of
the
process.
An
environment
is
changed
by
invoking
the
ENTER
ACCE'SS
SEG1ENT
or
ENTER
GLCBAL
AOCESS
SEGfENr
functions.
2-7