<s>
PACX	B-Device
(	O
Private	O
Automatic	O
Computer	O
eXchange	O
)	O
was	O
a	O
name	O
given	O
by	O
Gandalf	O
Technologies	O
to	O
their	O
family	O
of	O
data	B-Protocol
switching	I-Protocol
products	O
.	O
</s>
<s>
The	O
PACX	B-Device
was	O
a	O
centralized	O
switch	O
that	O
allowed	O
serial	O
connections	O
from	O
end	O
users	O
to	O
be	O
connected	O
to	O
any	O
one	O
of	O
a	O
number	O
of	O
computers	O
,	O
typically	O
mainframes	B-Architecture
.	O
</s>
<s>
Users	O
were	O
equipped	O
with	O
small	O
boxes	O
with	O
two	O
thumbwheels	O
on	O
them	O
,	O
and	O
by	O
rolling	O
the	O
wheels	O
to	O
a	O
given	O
two-digit	O
number	O
they	O
could	O
select	O
among	O
the	O
machines	O
connected	O
to	O
the	O
PACX	B-Device
.	O
</s>
<s>
In	O
typical	O
setups	O
,	O
the	O
PACX	B-Device
would	O
be	O
connected	O
to	O
computer	B-General_Concept
terminals	I-General_Concept
or	O
modems	B-Application
.	O
</s>
<s>
The	O
system	O
was	O
not	O
unlike	O
the	O
telephone	O
network	O
,	O
and	O
the	O
name	O
PACX	B-Device
was	O
deliberately	O
chosen	O
to	O
suggest	O
a	O
computer-side	O
analog	O
of	O
the	O
PABX	O
market	O
.	O
</s>
<s>
The	O
PACX	B-Device
,	O
with	O
its	O
mainframe	B-Architecture
utility	O
,	O
was	O
part	O
of	O
an	O
era	O
in	O
which	O
enterprise	O
data	O
services	O
were	O
seen	O
to	O
the	O
province	O
of	O
an	O
Office	B-Device
Controller	I-Device
.	O
</s>
<s>
The	O
Office	B-Device
Controller	I-Device
was	O
envisaged	O
as	O
a	O
central	O
switch	O
which	O
would	O
interconnect	O
and	O
create	O
all	O
applications	O
and	O
make	O
them	O
available	O
to	O
users	O
.	O
</s>
<s>
PABX	O
manufacturers	O
of	O
that	O
era	O
(	O
the	O
1980s	O
)	O
created	O
suites	O
of	O
data	O
applications	O
for	O
the	O
connection	O
of	O
users	O
to	O
mainframe	B-Architecture
applications	O
.	O
</s>
<s>
There	O
were	O
even	O
magazine	O
articles	O
touting	O
the	O
victory	O
of	O
the	O
PABX	O
as	O
an	O
Office	B-Device
Controller	I-Device
over	O
its	O
LAN	B-General_Concept
rivals	O
.	O
</s>
<s>
The	O
PACX	B-Device
was	O
a	O
data	O
PABX	O
without	O
the	O
voice	O
capability	O
.	O
</s>
<s>
With	O
the	O
development	O
of	O
LANs	B-General_Concept
and	O
cheap	O
PCs	O
with	O
their	O
attendant	O
client/server	O
applications	O
,	O
the	O
Office	B-Device
Controller	I-Device
vision	O
faded	O
away	O
.	O
</s>
<s>
It	O
is	O
being	O
re-established	O
in	O
new	O
guises	O
with	O
the	O
development	O
of	O
SIP	B-Application
with	O
Session	B-Protocol
Border	I-Protocol
Controllers	I-Protocol
and	O
Service	O
Oriented	O
Architectures	O
.	O
</s>
