<s>
QuickRing	B-Architecture
was	O
a	O
gigabit-rate	O
interconnect	B-General_Concept
that	O
combined	O
the	O
functions	O
of	O
a	O
computer	B-General_Concept
bus	I-General_Concept
and	O
a	O
network	B-Architecture
.	O
</s>
<s>
It	O
was	O
designed	O
at	O
Apple	O
Computer	O
as	O
a	O
multimedia	O
system	O
to	O
run	O
"	O
on	O
top	O
"	O
of	O
existing	O
local	B-Architecture
bus	I-Architecture
systems	O
inside	O
a	O
computer	O
,	O
but	O
was	O
later	O
taken	O
over	O
by	O
National	O
Semiconductor	O
and	O
repositioned	O
as	O
an	O
interconnect	B-General_Concept
for	O
parallel	O
computing	O
.	O
</s>
<s>
However	O
it	O
appears	O
to	O
have	O
been	O
an	O
inspiration	O
for	O
other	O
more	O
recent	O
technologies	O
,	O
such	O
as	O
HyperTransport	B-Device
.	O
</s>
<s>
QuickRing	B-Architecture
started	O
as	O
an	O
offshoot	O
of	O
the	O
fabled	O
Futurebus	B-Architecture
project	O
,	O
which	O
started	O
in	O
the	O
late	O
1970s	O
under	O
the	O
aegis	O
of	O
the	O
IEEE	O
.	O
</s>
<s>
The	O
Futurebus	B-Architecture
process	O
quickly	O
bogged	O
down	O
,	O
and	O
concluding	O
it	O
was	O
doomed	O
,	O
several	O
of	O
the	O
main	O
designers	O
left	O
the	O
effort	O
in	O
1987	O
to	O
try	O
again	O
on	O
smaller	O
projects	O
,	O
leading	O
to	O
both	O
QuickRing	B-Architecture
and	O
SCI	B-General_Concept
.	O
</s>
<s>
In	O
the	O
case	O
of	O
QuickRing	B-Architecture
the	O
main	O
proponent	O
was	O
Paul	O
Sweazey	O
of	O
National	O
Semiconductor	O
,	O
who	O
had	O
hosted	O
Futurebus	B-Architecture
's	O
cache	B-General_Concept
coherency	I-General_Concept
group	O
.	O
</s>
<s>
The	O
system	O
was	O
first	O
announced	O
publicly	O
at	O
the	O
1992	O
Worldwide	O
Developers	O
Conference	O
,	O
positioned	O
primarily	O
as	O
a	O
secondary	O
bus	O
for	O
computer	O
systems	O
to	O
carry	O
multiple	O
streams	O
of	O
digital	O
video	O
without	O
using	O
the	O
existing	O
backplane	B-Architecture
bus	O
.	O
</s>
<s>
Apple	O
was	O
particularly	O
interested	O
in	O
this	O
role	O
due	O
to	O
the	O
limitations	O
of	O
their	O
current	O
NuBus	B-Device
systems	O
in	O
terms	O
of	O
speed	O
.	O
</s>
<s>
They	O
envisioned	O
various	O
video	O
cards	O
using	O
a	O
second	O
connector	O
located	O
near	O
the	O
top	O
of	O
the	O
card	O
,	O
opposite	O
the	O
NuBus	B-Device
connector	O
on	O
the	O
bottom	O
,	O
to	O
talk	O
to	O
each	O
other	O
.	O
</s>
<s>
Optionally	O
,	O
one	O
of	O
the	O
cards	O
would	O
produce	O
compressed	O
output	O
,	O
which	O
could	O
be	O
sent	O
over	O
the	O
NuBus	B-Device
for	O
storage	O
or	O
display	O
.	O
</s>
<s>
Before	O
any	O
commercial	O
use	O
of	O
QuickRing	B-Architecture
,	O
newer	O
versions	O
of	O
PCI	B-Protocol
started	O
appearing	O
that	O
offered	O
performance	O
close	O
enough	O
to	O
QuickRing	B-Architecture
to	O
make	O
its	O
role	O
redundant	O
.	O
</s>
<s>
Apple	O
switched	O
to	O
an	O
all-PCI	O
based	O
computer	O
lineup	O
starting	O
in	O
1995	O
,	O
and	O
in	O
one	O
of	O
their	O
general	O
downsizings	O
in	O
the	O
early	O
90s	O
,	O
Apple	O
dropped	O
their	O
funding	O
for	O
QuickRing	B-Architecture
.	O
</s>
<s>
Sweazey	O
moved	O
back	O
to	O
National	O
Semiconductor	O
,	O
who	O
positioned	O
QuickRing	B-Architecture
as	O
a	O
high-speed	O
interconnect	B-General_Concept
.	O
</s>
<s>
Here	O
it	O
had	O
little	O
better	O
luck	O
,	O
competing	O
against	O
SCI	B-General_Concept
on	O
one	O
hand	O
,	O
and	O
ever-faster	O
versions	O
of	O
Ethernet	O
on	O
the	O
other	O
.	O
</s>
<s>
Efforts	O
were	O
made	O
to	O
standardize	O
QuickRing	B-Architecture
inside	O
the	O
existing	O
VMEbus	B-Architecture
system	O
using	O
some	O
redundant	O
pins	O
in	O
response	O
to	O
an	O
industry	O
effort	O
to	O
standardize	O
parallel	O
processing	O
hardware	O
,	O
but	O
nothing	O
ever	O
came	O
of	O
this	O
.	O
</s>
<s>
The	O
US	O
Navy	O
announced	O
several	O
tenders	O
for	O
QuickRing	B-Architecture
products	O
for	O
sonar	B-Application
data	O
processing	O
(	O
for	O
which	O
they	O
had	O
originally	O
had	O
Futurebus+	O
developed	O
)	O
,	O
but	O
it	O
is	O
unclear	O
whether	O
or	O
not	O
it	O
was	O
actually	O
used	O
in	O
this	O
role	O
.	O
</s>
<s>
The	O
basic	O
QuickRing	B-Architecture
system	O
consisted	O
of	O
a	O
number	O
of	O
single-direction	O
1-bit	O
serial	O
links	O
carrying	O
data	O
,	O
and	O
one	O
extra	O
line	O
carrying	O
a	O
50	O
MHz	O
clock	O
signal	O
.	O
</s>
<s>
Apple	O
's	O
implementation	O
consisted	O
of	O
six	O
data	O
lines	O
and	O
the	O
clock	O
line	O
using	O
twisted-pair	O
copper	O
wiring	O
(	O
using	O
LVDS	B-Architecture
)	O
embedded	O
in	O
a	O
thin	O
plastic	O
strip	O
.	O
</s>
<s>
National	O
Semiconductor	O
offered	O
a	O
variety	O
of	O
different	O
implementations	O
with	O
up	O
to	O
32	O
data	O
lines	O
,	O
as	O
well	O
as	O
the	O
same	O
signals	O
multiplexted	O
using	O
frequency-division	B-Protocol
multiplexing	I-Protocol
in	O
a	O
single	O
fibre	B-Architecture
optic	I-Architecture
cable	O
for	O
longer	O
links	O
between	O
machines	O
.	O
</s>
<s>
This	O
was	O
only	O
slightly	O
faster	O
than	O
contemporary	O
(	O
1993	O
)	O
versions	O
of	O
PCI	B-Protocol
at	O
~	O
130	O
MB/s	O
,	O
but	O
much	O
faster	O
than	O
NuBus	B-Device
of	O
the	O
same	O
era	O
,	O
at	O
about	O
20	O
MB/s	O
.	O
</s>
<s>
Each	O
QuickRing	B-Architecture
interface	O
contained	O
two	O
such	O
links	O
,	O
one	O
for	O
"	O
upstream	O
"	O
and	O
one	O
for	O
"	O
downstream	O
"	O
connections	O
in	O
a	O
point-to-point	O
ring	O
.	O
</s>
<s>
Since	O
QuickRing	B-Architecture
was	O
built	O
in	O
a	O
ring	O
topology	O
there	O
was	O
no	O
need	O
for	O
a	O
dedicated	O
switch	O
or	O
router	O
,	O
potentially	O
making	O
the	O
system	O
lower	O
cost	O
to	O
deploy	O
.	O
</s>
<s>
QuickRing	B-Architecture
routing	O
used	O
a	O
circuit	B-Protocol
switching	I-Protocol
system	O
,	O
in	O
which	O
the	O
message	O
path	O
is	O
set	O
up	O
before	O
the	O
data	O
is	O
sent	O
,	O
and	O
once	O
set	O
up	O
the	O
connection	O
is	O
very	O
lightweight	O
.	O
</s>
<s>
This	O
is	O
as	O
opposed	O
to	O
packet	B-Protocol
switching	I-Protocol
,	O
in	O
which	O
every	O
message	O
contains	O
all	O
of	O
the	O
data	O
needed	O
to	O
reach	O
the	O
destination	O
,	O
this	O
is	O
more	O
flexible	O
,	O
but	O
adds	O
overhead	O
.	O
</s>
