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rnAPTER 2
CBJOCTS
AND
OPERA'lORS
This
chapter
describes
the
432 environment
as
it
appears
to
the
I/O
controller
software.
It
:r;x:>ints
out
what
the
I/O
controller
can,
and
cannot,
do
in
the
432
system.
The
first
section
broadly
compares
the
facilities
provided
by
the
Interface
Processor
to
those
available
on
the
General
Data
Processor.
The
remaining
sections
describe
Interface
Processor
facilities
provided
for:
o
addressing
and
protection;
o
objects
for
program
environments;
o .
facil
it
ies
for
asynchronous
cannunication;
o
processes
and
storage
resource
management;
o
facilities
for
process
scheduling
and
dispatching.
Because a
great
many
facilities
are
common
to
both
pr.ocessors,
this
chapter
aoopts
the
approach
of
describing
IP
facilities
that
are
different
or
unique,
and
referring
the
reader
to
the
iAPX
432
General
Data
Processor
Architecture
Reference
Manual, (Order
Number
l7l860-00~for
descriptions
of
identical
features.
2-1.
SUMMARY
OF
IP
FACILITIES
This
section
surveys
the
Interface
Processor
by
comparing
it
to
the
General
Data
Processor.
When
reading
this
section,
it
is
useful
to
recall
the
notion,
introduced
in
chapter
1,
of
the
AP/IP
pair
co-operating
as
a
logical
I/O
processor.
In
this
arrangement,
the
Attached
Processor
fetches
instructions,
provides
arithmetic,
logical,
and
flCM-of-control
operations,
and
generates
Peripheral
Subsystem
address
references.
The
Interface
Processor
completes
the
logical
I/O
processor
by
supplying
the
faci.li
ties
for
operation
within
the
432
system,
plus
the
window mechanism
for
transferring
data
between
the
two
systems.
Windows
are
discussed
in
detail
in
chapter
3.
2-1