<s>
Zenith	B-Device
Cable	I-Device
Modem	I-Device
was	O
one	O
of	O
the	O
first	O
proprietary	O
cable	B-Device
modems	I-Device
.	O
</s>
<s>
The	O
Zenith	B-Device
Cable	I-Device
Modem	I-Device
was	O
originally	O
developed	O
for	O
a	O
mid-split	O
cable	B-Protocol
network	I-Protocol
in	O
the	O
mid-1980s	O
.	O
</s>
<s>
It	O
was	O
used	O
as	O
an	O
8-bit	O
full-height	O
PC/AT	B-Operating_System
-type	O
card	O
containing	O
an	O
Intel	B-Device
80186	I-Device
dedicated	O
CPU	O
,	O
connected	O
to	O
an	O
external	O
white	O
box	O
about	O
2	O
"	O
x	O
12	O
"	O
x	O
6	O
"	O
.	O
</s>
<s>
These	O
modified	O
modems	O
were	O
intended	O
to	O
support	O
the	O
Prodigy	O
Cable	B-Device
Modem	I-Device
trial	O
,	O
which	O
began	O
on	O
a	O
1500	O
homes-passed	O
fiber	O
node	O
in	O
El	O
Cajon	O
,	O
CA	O
.	O
</s>
<s>
The	O
initial	O
trial	O
consisted	O
of	O
a	O
Prodigy	O
server	O
in	O
the	O
El	O
Cajon	O
headend	O
,	O
connected	O
via	O
the	O
Microchannel-based	O
cable	B-Device
modem	I-Device
to	O
an	O
Olsen	O
Frequency	O
Translator	O
.	O
</s>
<s>
One	O
card	O
was	O
installed	O
in	O
rackmount	B-Application
PC	O
in	O
the	O
Federal	O
headend	O
,	O
another	O
in	O
the	O
El	O
Cajon	O
headend	O
.	O
</s>
<s>
The	O
new	O
design	O
used	O
the	O
same	O
size	O
external	O
case	O
,	O
added	O
LEDs	O
to	O
indicate	O
power/TX/RX/activity	O
and	O
replaced	O
the	O
full	O
sized	O
8-bit	O
ISA	O
card	O
with	O
a	O
smaller	O
16-bit	B-Device
version	O
.	O
</s>
<s>
The	O
modem	O
connected	O
to	O
the	O
card	O
used	O
a	O
15-pin	O
D-shell	B-Protocol
connector	O
—	O
which	O
exactly	O
matched	O
the	O
PC	O
's	O
game	O
connector	O
.	O
</s>
<s>
Nor	O
was	O
the	O
MAC	O
address	O
printed	O
in	O
a	O
machine	B-General_Concept
readable	I-General_Concept
(	O
bar	O
code	O
)	O
format	O
.	O
</s>
<s>
Cox	O
added	O
these	O
to	O
the	O
CM	O
prior	O
to	O
installation	O
,	O
and	O
tracked	O
the	O
subscriber	O
to	O
modem	O
MAC	O
address	O
in	O
an	O
Excel	B-Application
spreadsheet	I-Application
,	O
as	O
the	O
MAC	O
address	O
contained	O
too	O
many	O
digits	O
to	O
fit	O
into	O
any	O
fields	O
within	O
the	O
customer	O
billing	O
system	O
.	O
</s>
<s>
HW	O
revision	O
C	O
:	O
introduced	O
a	O
two	O
board	O
model	O
and	O
4	O
"	O
tall	O
case	O
that	O
would	O
allow	O
use	O
with	O
a	O
traditional	O
Ethernet	B-Protocol
10BASE-T	I-Protocol
connection	O
instead	O
of	O
an	O
internal	O
PC	B-Architecture
card	I-Architecture
.	O
</s>
<s>
The	O
external	O
models	O
used	O
an	O
RJ-14	O
style	O
phone	B-Protocol
jack	I-Protocol
for	O
serial	O
control	O
,	O
configuration	O
,	O
and	O
management	O
using	O
a	O
Zenith	O
supplied	O
utility	O
application	O
.	O
</s>
<s>
HW	O
revision	O
E	O
:	O
introduced	O
dual	O
10BaseT	B-Protocol
interface	O
for	O
University	O
of	O
California	O
San	O
Diego	O
,	O
and	O
other	O
customers	O
.	O
</s>
<s>
The	O
initial	O
Zenith	O
"	O
Headend	O
"	O
design	O
was	O
to	O
use	O
a	O
residential	O
cable	B-Device
modem	I-Device
inside	O
a	O
server	O
,	O
and	O
a	O
frequency	O
translator	O
to	O
convert	O
the	O
upstream	O
transmit	O
frequency	O
to	O
the	O
downstream	O
receive	O
frequency	O
.	O
</s>
<s>
These	O
plus	O
three	O
other	O
Channelmizers	O
were	O
interconnected	O
to	O
an	O
8	O
port	O
Cisco	O
Catalyst	O
1200	O
Ethernet	B-Protocol
switch	I-Protocol
with	O
single	O
mode	O
FDDI	B-Protocol
uplink	O
for	O
a	O
4	O
device	O
,	O
140km	O
FDDI	B-Protocol
ring	I-Protocol
around	O
San	O
Diego	O
county	O
.	O
</s>
<s>
Prodigy	O
was	O
deployed	O
over	O
cable	B-Device
modem	I-Device
to	O
200	O
users	O
in	O
time	O
for	O
the	O
1994	O
Western	O
Cable	O
Show	O
.	O
</s>
<s>
To	O
grow	O
the	O
system	O
from	O
16	O
users	O
in	O
three	O
fiber	O
nodes	O
,	O
to	O
200	O
required	O
adding	O
what	O
became	O
64,000	O
homes	O
passed	O
,	O
making	O
the	O
Cox	O
San	O
DiegoProdigy	O
cable	B-Device
modem	I-Device
field	O
trial	O
the	O
world	O
's	O
largest	O
cable	B-Device
modem	I-Device
deployment	O
(	O
by	O
service	O
area	O
)	O
at	O
the	O
time	O
.	O
</s>
<s>
Activity	O
is	O
defined	O
as	O
any	O
RF	O
energy	O
,	O
intelligible	O
or	O
not	O
,	O
at	O
an	O
absolute	O
amplitude	B-Application
of	O
-25	O
dBmV	O
into	O
the	O
device	O
receive	O
port	O
within	O
a	O
1MHz	O
or	O
6MHz	O
passband	O
(	O
500kbit/s	O
or	O
4	O
Mbit/s	O
respectively	O
.	O
)	O
</s>
<s>
If	O
the	O
CM	O
were	O
able	O
to	O
decode	O
its	O
own	O
burst	O
,	O
and	O
correctly	O
compare	O
a	O
checksum	B-Algorithm
of	O
the	O
first	O
17	O
bytes	O
of	O
the	O
packet	B-Protocol
,	O
it	O
would	O
declare	O
no-collision	O
,	O
and	O
continue	O
.	O
</s>
<s>
If	O
there	O
was	O
a	O
checksum	B-Algorithm
error	O
,	O
it	O
would	O
declare	O
a	O
collision	O
,	O
and	O
stop	O
transmitting	O
after	O
the	O
19th	O
byte	O
.	O
</s>
<s>
This	O
was	O
easily	O
and	O
directly	O
measured	O
using	O
Novell	O
LANalyzer	O
software	O
on	O
a	O
dedicated	O
Windows	B-Application
3.1	I-Application
for	O
Workgroups	O
PC	O
.	O
</s>
<s>
By	O
November	O
20	O
,	O
1996	O
,	O
Zenith	O
released	O
SNMP	B-Protocol
MIBs	O
and	O
management	O
for	O
their	O
Channelmizer	O
under	O
software	O
release	O
9.32	O
,	O
under	O
the	O
title	O
"	O
Node	O
Data	O
Controller	O
SNMP	B-Protocol
"	O
.	O
</s>
<s>
The	O
physical	O
possession	O
of	O
a	O
properly	O
installed	O
modem	O
connected	O
the	O
subscriber	O
to	O
the	O
network	O
,	O
and	O
the	O
use	O
of	O
this	O
modem	O
with	O
a	O
packet	B-Protocol
sniffer	I-Protocol
would	O
enable	O
full	O
viewing	O
of	O
all	O
transmitted	O
and	O
received	O
packets	O
from	O
every	O
user	O
sharing	O
that	O
frequency	O
translator	O
.	O
</s>
<s>
While	O
not	O
directly	O
competing	O
against	O
an	O
existing	O
product	O
—	O
residential	O
ISDN	B-Protocol
penetration	O
was	O
sub	O
0.1	O
%	O
,	O
the	O
technology	O
had	O
severe	O
growing	O
pains	O
:	O
</s>
<s>
Channelmizer	O
lock	B-General_Concept
up	I-General_Concept
,	O
cell	O
phone	O
used	O
near	O
headend	O
cable	B-Device
modem	I-Device
,	O
PLL	O
unlocked	O
.	O
</s>
<s>
Return	O
path	O
alignment	O
and	O
headend	O
combining	O
:	O
Independently	O
develop	O
the	O
"	O
X-point	O
"	O
return	O
path	O
alignment	O
and	O
amplitude	B-Application
compensation	O
process	O
.	O
</s>
<s>
Due	O
to	O
the	O
Amplitude	B-Device
Modulation	I-Device
(	O
AM	O
)	O
format	O
of	O
the	O
return	O
path	O
FP	O
lasers	O
,	O
a	O
+25	O
dBmV	O
CW	O
tone	O
injected	O
at	O
the	O
fiber	O
node	O
status	O
monitoring	O
module	O
would	O
not	O
arrive	O
at	O
the	O
headend	O
with	O
constant	O
amplitude	B-Application
.	O
</s>
<s>
Downstream	O
input	O
to	O
each	O
cable	B-Device
modem	I-Device
of	O
+5	O
dBmV	O
±	O
2dB	O
.	O
</s>
<s>
In	O
comparison	O
,	O
a	O
2003	O
DOCSIS	B-Protocol
2.0	O
compliant	O
CMTS	O
operating	O
at	O
0.5	O
to	O
1dB	O
from	O
theory	O
dprovide	O
both	O
16QAM	B-Device
and	O
64	O
QAM	B-Device
in	O
6.4MHz	O
at	O
25dB	O
C/noise	O
,	O
and	O
in	O
some	O
cases	O
negative	O
C/I	O
.	O
</s>
<s>
Add	O
to	O
that	O
a	O
comb	B-Algorithm
generator	I-Algorithm
with	O
46	O
CW	O
tones	O
,	O
an	O
HP	O
Calan	O
1776	O
"	O
portable	O
"	O
spectrum	O
analyzer	O
.	O
</s>
<s>
Not	O
all	O
amplifiers	O
contained	O
a	O
good	O
return-path	O
test	O
point	O
,	O
so	O
the	O
repair	O
lab	O
was	O
asked	O
to	O
modify	O
some	O
line	O
extender	O
diplex	O
filters	O
to	O
pass	O
the	O
forward	O
,	O
and	O
divert	O
the	O
return	O
path	O
to	O
an	O
F	B-Protocol
connector	I-Protocol
.	O
</s>
<s>
Any	O
signal	O
entering	O
an	O
amplifier	O
with	O
an	O
amplitude	B-Application
above	O
-45	O
dBmV	O
was	O
located	O
and	O
fixed	O
.	O
</s>
<s>
Modeled	O
after	O
the	O
University	O
of	O
California	O
,	O
San	O
Diego	O
Telecommunications	O
NOC	O
at	O
the	O
Central	O
Utilities	O
Building	O
,	O
Novell	O
LANalyzer	O
software	O
w/	O
internal	O
cable	B-Device
modem	I-Device
,	O
and	O
a	O
technician	O
to	O
manually	O
move	O
the	O
test	O
connection	O
between	O
frequency	O
translators	O
.	O
</s>
<s>
HP	B-Application
OpenView	I-Application
(	O
HPOV	O
)	O
and	O
a	O
24	O
port	O
HP	O
AdvanceStack	O
Ethernet	B-Protocol
HUB	I-Protocol
with	O
AUI	O
"	O
uplink	O
"	O
was	O
available	O
.	O
</s>
<s>
This	O
combination	O
allowed	O
the	O
AdvanceStack	O
hub	B-Protocol
to	O
send	O
out	O
IPX	O
diagnostic	O
packets	O
to	O
the	O
NDIS	O
driver	O
in	O
each	O
PC	O
.	O
</s>
<s>
Assuming	O
the	O
PC	O
was	O
running	O
the	O
driver	O
at	O
all	O
times	O
,	O
the	O
HP	B-Application
OpenView	I-Application
application	O
would	O
display	O
the	O
NetWare	B-Operating_System
device	O
ID	O
–	O
00000	O
,	O
mac-address	O
as	O
there	O
was	O
no	O
real	O
NetWare	B-Operating_System
serverrouter	O
.	O
</s>
<s>
The	O
management	O
software	O
would	O
generate	O
NDIS	O
"	O
diagnostic	O
pings	O
"	O
from	O
the	O
hub	B-Protocol
,	O
and	O
report	O
the	O
number	O
of	O
successful	O
responses	O
.	O
</s>
<s>
Rebooting	O
the	O
PC	O
,	O
loading	O
and	O
unloading	O
the	O
driver	O
,	O
or	O
experiencing	O
RF	O
faults	O
would	O
cause	O
each	O
cable	B-Device
modem	I-Device
to	O
transition	O
from	O
active	O
to	O
inactive	O
hundreds	O
of	O
times	O
per	O
day	O
.	O
</s>
<s>
HPOV	O
could	O
export	O
the	O
log	O
file	O
to	O
a	O
Paradox	B-Application
database	I-Application
for	O
later	O
analysis	O
and	O
trending	O
.	O
</s>
<s>
Eventually	O
,	O
this	O
technique	O
became	O
mandatory	O
in	O
DOCSIS	B-Protocol
3.0	I-Protocol
,	O
although	O
it	O
was	O
rejected	O
and	O
ignored	O
for	O
three	O
years	O
as	O
a	O
"	O
proprietary	O
extension	O
to	O
DOCSIS	B-Protocol
"	O
by	O
@Home	O
and	O
copied	O
by	O
every	O
DOCSIS	B-Protocol
CMTS	O
vendor	O
.	O
</s>
<s>
By	O
September	O
1994	O
,	O
the	O
NOC	O
was	O
expanded	O
with	O
the	O
introduction	O
of	O
two	O
@	O
Cisco	O
Catalyst	O
1200	O
Ethernet	O
to	O
FDDI	B-Protocol
switches	O
,	O
and	O
two	O
@	O
Cabletron	O
MMAC-three	O
FNB	O
hubs	B-Protocol
(	O
six	O
Ethernet	O
plus	O
two	O
FDDI	B-Protocol
)	O
,	O
constructing	O
a	O
reliable	O
path	O
from	O
the	O
Federal	O
Headend	O
to	O
the	O
El	O
Cajon	O
headend	O
,	O
and	O
eliminating	O
one	O
unreliable	O
path	O
between	O
the	O
AdvanceStack	O
hub	B-Protocol
and	O
the	O
various	O
Channelmizers	O
and	O
frequency	O
translators	O
.	O
</s>
<s>
CUs-SeeMe	B-Protocol
and	O
Apple	B-Application
QuickTime	I-Application
Conferencing	O
1.0	O
beta	O
ran	O
over	O
the	O
Zenith	O
and	O
Lancity	O
proprietary	O
cable	B-Device
modems	I-Device
when	O
the	O
RF	O
path	O
was	O
sufficiently	O
clean	O
.	O
</s>
<s>
These	O
modems	O
were	O
able	O
to	O
interoperate	O
on	O
the	O
same	O
RF	O
fiber	O
nodes	O
using	O
Frequency	B-Protocol
Division	I-Protocol
Multiplexing	I-Protocol
,	O
using	O
an	O
Ethernet	B-Protocol
switch	I-Protocol
to	O
join	O
the	O
otherwise	O
incompatible	O
networks	O
.	O
</s>
<s>
Late	O
in	O
the	O
beta	O
,	O
160	O
x	O
120	O
pixel	O
video	O
was	O
increased	O
to	O
320	O
x	O
240	O
,	O
and	O
the	O
audio	O
quality	O
greatly	O
improved	O
on	O
the	O
Apple	O
Power	B-Device
Macintosh	I-Device
7100	I-Device
AV	O
.	O
</s>
<s>
Cogeco	O
in	O
Canada	O
launched	O
with	O
the	O
4	O
Mbit/s	O
,	O
external	O
Rev	O
D	O
cable	B-Device
modem	I-Device
in	O
roughly	O
1996	O
,	O
and	O
by	O
August	O
1997	O
had	O
2500	O
subscribers	O
.	O
</s>
<s>
It	O
has	O
no	O
understanding	O
of	O
the	O
Layer-3	B-Application
ARP	O
protocol	O
.	O
</s>
<s>
Thus	O
ARP	O
storms	O
through	O
the	O
layer-2	B-Protocol
switches	O
used	O
in	O
the	O
first	O
headend	O
designs	O
would	O
clog	O
the	O
network	O
.	O
</s>
<s>
The	O
Layer-2	B-Protocol
switches	O
and	O
Layer-3	B-Application
routers	B-Protocol
of	O
the	O
time	O
did	O
not	O
perform	O
any	O
QOS	O
or	O
rate	O
limiting	O
,	O
thus	O
a	O
4	O
Mbit/s	O
input	O
port	O
on	O
the	O
Channelmizer	O
could	O
be	O
flooded	O
with	O
up	O
to	O
10	O
Mbit/s	O
of	O
traffic	O
bursts	O
.	O
</s>
<s>
This	O
amplifier	O
contained	O
a	O
design	O
defect	O
whereby	O
the	O
pad	O
and	O
equalizer	O
plug-in	B-Application
modules	O
would	O
literally	O
fall	O
off	O
the	O
circuit	O
board	O
when	O
the	O
device	O
was	O
opened	O
.	O
</s>
<s>
This	O
fault	O
was	O
documented	O
and	O
proven	O
as	O
a	O
result	O
of	O
Cogeco	O
's	O
first	O
DOCSIS	B-Protocol
deployment	O
with	O
the	O
Cisco	O
uBR7246	O
,	O
MC11-FPGA	O
linecard	O
,	O
and	O
IOS	O
11.3(4 )	O
NA	O
,	O
which	O
contained	O
the	O
"	O
flap	O
list.	O
"	O
</s>
