<s>
Multibus	B-Protocol
is	O
a	O
computer	B-General_Concept
bus	I-General_Concept
standard	O
used	O
in	O
industrial	O
systems	O
.	O
</s>
<s>
The	O
Multibus	B-Protocol
specification	O
was	O
important	O
because	O
it	O
was	O
a	O
robust	O
,	O
well-thought	O
out	O
industry	O
standard	O
with	O
a	O
relatively	O
large	O
form	O
factor	O
,	O
so	O
complex	O
devices	O
could	O
be	O
designed	O
on	O
it	O
.	O
</s>
<s>
Because	O
it	O
was	O
a	O
well-defined	O
and	O
well-documented	O
industry	O
standard	O
,	O
it	O
allowed	O
a	O
Multibus-compatible	O
industry	O
to	O
grow	O
around	O
it	O
,	O
with	O
many	O
companies	O
making	O
card	O
cages	O
and	O
enclosures	O
for	O
it	O
.	O
</s>
<s>
Many	O
others	O
made	O
CPU	B-Device
,	O
memory	O
,	O
and	O
other	O
peripheral	O
boards	O
.	O
</s>
<s>
In	O
1982	O
there	O
were	O
over	O
100	O
Multibus	B-Protocol
board	O
and	O
systems	O
manufacturers	O
.	O
</s>
<s>
This	O
allowed	O
complex	O
systems	O
to	O
be	O
built	O
from	O
commercial	O
off-the-shelf	O
hardware	O
,	O
and	O
also	O
allowed	O
companies	O
to	O
innovate	O
by	O
designing	O
a	O
proprietary	O
Multibus	B-Protocol
board	O
and	O
then	O
integrating	O
it	O
with	O
other	O
vendors	O
 '	O
hardware	O
to	O
create	O
a	O
system	O
.	O
</s>
<s>
A	O
good	O
example	O
of	O
this	O
was	O
Sun	O
Microsystems	O
with	O
their	O
Sun-1	B-Device
and	O
Sun-2	B-Device
workstations	B-Device
.	O
</s>
<s>
Sun	O
built	O
custom-designed	O
CPU	B-Device
,	O
memory	O
,	O
SCSI	B-Architecture
,	O
and	O
video	O
display	O
boards	O
,	O
and	O
then	O
added	O
3Com	O
Ethernet	O
networking	O
boards	O
,	O
Xylogics	B-Architecture
SMD	O
disk	B-General_Concept
controllers	I-General_Concept
,	O
Ciprico	O
Tapemaster	O
1/2inch	O
tape	O
controllers	O
,	O
Sky	O
Floating	B-General_Concept
Point	I-General_Concept
Processor	I-General_Concept
,	O
and	O
Systech	O
16-port	O
Terminal	O
Interfaces	O
in	O
order	O
to	O
configure	O
the	O
system	O
as	O
a	O
workstation	B-Device
or	O
a	O
file	B-Application
server	I-Application
.	O
</s>
<s>
Other	O
workstation	B-Device
vendors	O
who	O
used	O
Multibus-based	O
designs	O
included	O
HP/Apollo	O
and	O
Silicon	O
Graphics	O
.	O
</s>
<s>
Multibus	B-Protocol
is	O
an	O
asynchronous	B-General_Concept
bus	I-General_Concept
that	O
accommodates	O
devices	O
with	O
various	O
transfer	O
rates	O
while	O
maintaining	O
maximum	O
throughput	O
.	O
</s>
<s>
It	O
had	O
20	O
address	O
lines	O
so	O
it	O
could	O
address	O
up	O
to	O
1	O
Mb	O
of	O
Multibus	B-Protocol
memory	O
and	O
1	O
Mb	O
of	O
I/O	O
locations	O
.	O
</s>
<s>
Most	O
Multibus	B-Protocol
I/O	O
devices	O
only	O
decoded	O
the	O
first	O
64	O
Kb	O
of	O
address	O
space	O
.	O
</s>
<s>
Multibus	B-Protocol
supported	O
multi-master	B-Architecture
functionality	O
that	O
allowed	O
it	O
to	O
share	O
the	O
Multibus	B-Protocol
with	O
multiple	O
processors	O
and	O
other	O
DMA	B-General_Concept
devices	O
.	O
</s>
<s>
The	O
standard	O
Multibus	B-Protocol
form	O
factor	O
was	O
a	O
,	O
circuit	O
board	O
with	O
two	O
ejection	O
levers	O
on	O
the	O
front	O
edge	O
.	O
</s>
<s>
The	O
wider	O
P1	O
bus	O
which	O
pin	O
assignment	O
was	O
defined	O
by	O
the	O
Multibus	B-Protocol
specification	O
.	O
</s>
<s>
Multibus	B-Protocol
includes	O
the	O
following	O
buses	O
:	O
</s>
<s>
Companies	O
like	O
Northwest	O
Technical	O
still	O
provide	O
"	O
End	O
of	O
Life	O
"	O
products	O
for	O
Multibus	B-Protocol
I	O
.	O
</s>
<s>
It	O
uses	O
TTL	O
(	O
"	O
Fast	O
"	O
series	O
)	O
gates	O
for	O
drivers	O
and	O
the	O
Backplane	O
Connectors	O
are	O
DIN	O
41612	O
type	O
C	O
.	O
Multibus	B-Protocol
II	O
is	O
not	O
yet	O
considered	O
obsolete	O
,	O
but	O
considered	O
mature	O
;	O
however	O
it	O
is	O
not	O
recommended	O
for	O
new	O
designs	O
.	O
</s>
<s>
IEEE-STD-1296	O
:	O
High-performance	O
synchronous	O
32-bit	O
bus	O
:	O
Multibus	B-Protocol
II	O
,	O
released	O
in	O
1987	O
,	O
and	O
1994	O
.	O
</s>
<s>
Multibus-II	O
hardware	O
running	O
the	O
iRMX	B-Operating_System
operating	O
system	O
is	O
used	O
in	O
the	O
majority	O
of	O
the	O
core	O
Automatic	O
Train	O
Supervision	O
subsystems	O
on	O
CLSCS	O
,	O
the	O
London	O
Underground	O
Central	O
line	O
Signals	O
Control	O
System	O
.	O
</s>
<s>
The	O
Automatic	O
Train	O
Supervision	O
elements	O
use	O
a	O
mixture	O
of	O
iRMX	B-Operating_System
on	O
Multibus	B-Protocol
,	O
and	O
Solaris	B-Application
on	O
SPARC	B-Architecture
computers	O
.	O
</s>
<s>
Sixteen	O
Multibus-based	O
Local	O
Site	O
Computers	O
are	O
distributed	O
along	O
the	O
line	O
together	O
with	O
six	O
central	O
Multibus-based	O
subsystems	O
in	O
the	O
control	O
centre	O
.	O
</s>
<s>
Real	B-General_Concept
time	I-General_Concept
control	O
and	O
communications	O
functions	O
are	O
provided	O
by	O
the	O
Multibus-based	O
processors	O
and	O
Sun	O
workstations	B-Device
provide	O
database	O
functions	O
and	O
the	O
operator	O
consoles	O
in	O
the	O
control	O
room	O
.	O
</s>
<s>
The	O
safety-critical	B-Application
Automatic	O
Train	O
Protection	O
component	O
is	O
provided	O
by	O
trackside	O
and	O
train-borne	O
equipment	O
that	O
does	O
not	O
use	O
Multibus	B-Protocol
.	O
</s>
<s>
In	O
the	O
control	O
centre	O
,	O
Westinghouse	O
also	O
provided	O
a	O
cut-down	O
mimic	O
of	O
the	O
system	O
for	O
staff	O
training	O
and	O
software	O
test	O
purposes	O
using	O
much	O
of	O
the	O
same	O
hardware	O
and	O
software	O
as	O
the	O
full	O
ATS	O
system	O
,	O
but	O
connected	O
to	O
a	O
computer	O
(	O
also	O
Multibus-II	O
and	O
Sun	O
based	O
)	O
to	O
simulate	O
train	O
movements	O
and	O
signalling	O
behaviour	O
.	O
</s>
<s>
Oslo	O
Metro	O
or	O
Oslo	O
Tunnelbane	O
uses	O
a	O
similar	O
,	O
although	O
less	O
complex	O
Westinghouse-supplied	O
Multibus	B-Protocol
hardware	O
control	O
system	O
through	O
the	O
central	O
Common	O
Tunnel	O
or	O
Fellestunnelen	O
tracks	O
,	O
but	O
was	O
expected	O
to	O
be	O
decommissioned	O
in	O
2011	O
.	O
</s>
