<s>
Apple	B-Protocol
Attachment	I-Protocol
Unit	I-Protocol
Interface	I-Protocol
(	O
AAUI	B-Protocol
)	O
is	O
a	O
mechanical	O
re-design	O
by	O
Apple	O
of	O
the	O
standard	O
Attachment	B-Protocol
Unit	I-Protocol
Interface	I-Protocol
(	O
AUI	O
)	O
used	O
to	O
connect	O
Ethernet	O
transceivers	O
to	O
computer	O
equipment	O
.	O
</s>
<s>
AUI	O
was	O
popular	O
in	O
the	O
era	O
before	O
the	O
dominance	O
of	O
10BASE-T	B-Protocol
networking	O
that	O
started	O
in	O
the	O
early	O
1990s	O
;	O
AAUI	B-Protocol
was	O
an	O
attempt	O
to	O
make	O
the	O
connector	O
much	O
smaller	O
and	O
more	O
user	O
friendly	O
,	O
though	O
the	O
proprietary	O
nature	O
of	O
the	O
interface	O
was	O
also	O
criticized	O
.	O
</s>
<s>
AAUI	B-Protocol
is	O
part	O
of	O
a	O
system	O
of	O
Ethernet	O
peripherals	O
intended	O
to	O
make	O
connecting	O
over	O
Ethernet	O
much	O
easier	O
.	O
</s>
<s>
At	O
the	O
time	O
of	O
the	O
introduction	O
of	O
AAUI	B-Protocol
,	O
Ethernet	O
systems	O
usually	O
were	O
10BASE2	O
,	O
also	O
known	O
as	O
thinnet	O
.	O
</s>
<s>
Instead	O
of	O
a	O
single	O
BNC	B-Protocol
connector	I-Protocol
that	O
is	O
inserted	O
into	O
a	O
T-connector	O
placed	O
inline	O
,	O
the	O
FriendlyNet	O
transceiver	O
has	O
two	O
BNC	B-Protocol
connectors	I-Protocol
,	O
one	O
on	O
each	O
side	O
,	O
to	O
which	O
the	O
cables	O
are	O
attached	O
.	O
</s>
<s>
FriendlyNet	O
equipment	O
was	O
quite	O
expensive	O
and	O
even	O
third-party	O
AAUI	B-Protocol
transceivers	O
were	O
rather	O
expensive	O
.	O
</s>
<s>
Additionally	O
,	O
AAUI	B-Protocol
held	O
no	O
advantage	O
for	O
any	O
system	O
other	O
than	O
10BASE2	O
and	O
thus	O
as	O
10BASE-T	B-Protocol
became	O
ubiquitous	O
it	O
became	O
impossible	O
to	O
justify	O
the	O
cost	O
of	O
an	O
external	O
transceiver	O
at	O
all	O
.	O
</s>
<s>
Macintosh	B-Device
Quadra	I-Device
,	O
Centris	B-Device
,	O
PowerBook	B-Device
500	I-Device
,	O
Duo	O
Dock	O
II	O
(	O
for	O
PowerBook	B-Device
Duo	I-Device
)	O
and	O
early	O
Power	B-Device
Macintoshes	I-Device
have	O
AAUI	B-Protocol
ports	O
,	O
which	O
require	O
external	O
transceivers	O
.	O
</s>
<s>
By	O
the	O
time	O
AAUI	B-Protocol
was	O
nearing	O
the	O
end	O
of	O
its	O
life	O
,	O
an	O
AAUI	B-Protocol
transceiver	O
could	O
cost	O
even	O
more	O
than	O
an	O
inexpensive	O
Ethernet	O
card	O
on	O
a	O
PC	O
—	O
a	O
disproportionate	O
amount	O
—	O
as	O
network	O
cards	O
for	O
PCs	O
did	O
not	O
become	O
commodity	O
items	O
until	O
the	O
spread	O
of	O
high-speed	O
access	O
to	O
the	O
Internet	O
in	O
the	O
early	O
21st	O
century	O
.	O
</s>
<s>
Later	O
models	O
include	O
both	O
AAUI	B-Protocol
and	O
modular	O
connector	O
ports	O
for	O
directly	O
connecting	O
10BASE-T	B-Protocol
;	O
either	O
can	O
be	O
used	O
,	O
but	O
not	O
both	O
at	O
the	O
same	O
time	O
.	O
</s>
<s>
AAUI	B-Protocol
connectors	O
are	O
also	O
present	O
on	O
some	O
Processor	B-Device
Direct	I-Device
Slot	I-Device
Ethernet	O
adapter	O
cards	O
used	O
in	O
Macintosh	B-Device
LC	I-Device
and	O
Performa	B-Device
machines	O
.	O
</s>
<s>
AAUI	B-Protocol
had	O
disappeared	O
by	O
the	O
late	O
1990s	O
,	O
when	O
new	O
Apple	O
machines	O
,	O
starting	O
with	O
the	O
beige	O
Power	B-Device
Macintosh	I-Device
G3	I-Device
series	O
,	O
include	O
RJ-45	O
jacks	O
instead	O
of	O
both	O
.	O
</s>
<s>
Many	O
third	O
parties	O
also	O
created	O
AAUI	B-Protocol
transceivers	O
.	O
</s>
<s>
AUI	O
uses	O
a	O
full-sized	O
15-pin	B-Protocol
D	I-Protocol
connector	I-Protocol
(	O
model	O
DA-15	B-Protocol
)	O
that	O
uses	O
a	O
sliding	O
clip	O
for	O
mechanical	O
connections	O
in	O
place	O
of	O
thumbscrews	O
.	O
</s>
<s>
AAUI	B-Protocol
replaces	O
these	O
with	O
a	O
small	O
14-position	O
,	O
0.05-inch-spaced	O
ribbon	O
contact	O
connector	O
.	O
</s>
<s>
The	O
connector	O
may	O
have	O
been	O
changed	O
to	O
avoid	O
confusion	O
with	O
the	O
monitor	O
port	O
on	O
early	O
Macintoshes	B-Device
,	O
which	O
also	O
uses	O
a	O
15-pin	B-Protocol
D	I-Protocol
connector	I-Protocol
.	O
</s>
<s>
The	O
connector	O
locks	O
into	O
position	O
using	O
two	O
clips	O
or	O
hooks	O
on	O
the	O
sides	O
of	O
the	O
connector	O
outside	O
of	O
the	O
D	O
shell	O
(	O
where	O
screws	O
often	O
are	O
on	O
D	B-Protocol
subs	I-Protocol
)	O
which	O
automatically	O
clicks	O
on	O
when	O
plugged	O
in	O
,	O
and	O
can	O
be	O
removed	O
by	O
pulling	O
back	O
on	O
a	O
sliding	O
sheath	O
over	O
the	O
body	O
of	O
the	O
connector	O
,	O
disengaging	O
the	O
hooks	O
.	O
</s>
<s>
Third-party	O
AAUI	B-Protocol
devices	O
often	O
omit	O
this	O
sheath	O
,	O
requiring	O
the	O
user	O
to	O
directly	O
squeeze	O
small	O
tabs	O
on	O
the	O
sides	O
of	O
the	O
plug	O
housing	O
to	O
detach	O
the	O
hooks	O
.	O
</s>
<s>
AAUI	B-Protocol
signals	O
have	O
the	O
same	O
description	O
,	O
function	O
,	O
and	O
electrical	O
requirements	O
as	O
the	O
Attachment	B-Protocol
Unit	I-Protocol
Interface	I-Protocol
(	O
AUI	O
)	O
signals	O
of	O
the	O
same	O
name	O
,	O
as	O
detailed	O
in	O
IEEE	O
802.3-1990	O
CSMA/CD	O
Standard	O
,	O
section	O
7	O
,	O
with	O
the	O
exception	O
that	O
most	O
hosts	O
provide	O
only	O
5	O
volts	O
of	O
power	O
rather	O
than	O
the	O
12	O
volts	O
required	O
for	O
most	O
AUI	O
transceivers	O
.	O
</s>
<s>
An	O
adapter	O
containing	O
a	O
power	O
supply	O
to	O
provide	O
the	O
required	O
12	O
volts	O
was	O
available	O
from	O
Apple	O
to	O
permit	O
connection	O
of	O
standard	O
AUI	O
transceivers	O
to	O
an	O
AAUI	B-Protocol
port	O
—	O
this	O
facilitated	O
direct	O
connection	O
to	O
10BASE-F	O
(	O
fibre	B-Architecture
optic	I-Architecture
)	O
and	O
10BASE5	O
(	O
ThickNet	O
)	O
Ethernet	O
networks	O
,	O
for	O
which	O
AAUI	B-Protocol
transceivers	O
are	O
not	O
available	O
.	O
</s>
