MULTIPORT
MEMORY
SYSTEM
The system has growth
capabi
Ii
ty of
up
to 6 ports per
memory unit. A memory unit may
contain
16K
or32K words.
This
architecture
allows
flexibility
in growth patterns
and provides high memory bandwidth, essential to
multi-
proc essor systems.
MANUAL
PARTITIONING
CAPABILITY
Manual
partitioning
capabi lity
is
afforded for
all
system
units. Thus, besides
the
primary
advantage
of increased
throughput, a secondary
advantage
of a multiprocessor
system
is
the
"fail-soft"
abi I ity.
Given
a
duplicate
unit,
any unit
can
be partitioned by
selectively
disabling
it
from
the system buses. Depending on
the
type of fai ling unit,
the system
wi
II
be
operable,
with some degree of degraded
performance.
An
alternate
processor bus with dual system
capabilities
can
be provided.
MULTIPROCESSOR
CONTROL
FUNCTION
A multiprocessor control function is provided on
all
multi-
processor systems. This function provides these basic features:
1.
Control of
the
External Direct
Input/Output
bus (Ex-
ternal DIO), used for controlling system maintenance
and special purpose units such as analog
to
digital
converters.
2. Central control of system partitioning.
3.
Centralized
interrupt system, providing
capability
for
the operating system to use interrupts
to
schedule tasks
independently of
the
number of basic processors
pres-
ent
in a system.
4.
Processor
to
processor communication
via
processor
buses.
SHARED
INPUT/OUTPUT
In a multiprocessor system, any basic processor may
direct
I/o
actions
to any
I/O
processor.
Specifically,
any
basic
processor
can
issue
an
SIO,
no,
TDV, or HIO
instruc-
tion to begin, test, or stop
any
I/O
process. However,
the
"end-action
ll
sequence
of
the
I/O
process is
directed
to
one of
the
basic processors in
the
system by
the
System
Control Processor. This
feature
(accomplished by setting
a pair of configuration control switches) allows
dedicating
I/o
end-action
tasks to a single processor and avoids
con-
flict
resolution problems.
Multiprocessor Features 7
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