<s>
Apollo	O
Computer	O
Inc.	O
,	O
founded	O
in	O
1980	O
in	O
Chelmsford	O
,	O
Massachusetts	O
,	O
by	O
William	O
Poduska	O
(	O
a	O
founder	O
of	O
Prime	O
Computer	O
)	O
and	O
others	O
,	O
developed	O
and	O
produced	O
Apollo/Domain	B-Device
workstations	B-Device
in	O
the	O
1980s	O
.	O
</s>
<s>
Along	O
with	O
Symbolics	O
and	O
Sun	O
Microsystems	O
,	O
Apollo	O
was	O
one	O
of	O
the	O
first	O
vendors	O
of	O
graphical	O
workstations	B-Device
in	O
the	O
1980s	O
.	O
</s>
<s>
Like	O
computer	O
companies	O
at	O
the	O
time	O
and	O
unlike	O
manufacturers	O
of	O
IBM	B-Device
PC	I-Device
compatibles	O
,	O
Apollo	O
produced	O
much	O
of	O
its	O
own	O
hardware	O
and	O
software	O
.	O
</s>
<s>
The	O
brand	O
(	O
as	O
"	O
HP	O
Apollo	O
"	O
)	O
was	O
resurrected	O
in	O
2014	O
as	O
part	O
of	O
HP	O
's	O
high-performance	B-Architecture
computing	I-Architecture
portfolio	O
.	O
</s>
<s>
In	O
1981	O
,	O
the	O
company	O
unveiled	O
the	O
DN100	O
workstation	B-Device
,	O
which	O
used	O
the	O
Motorola	B-Device
68000	I-Device
microprocessor	I-Device
.	O
</s>
<s>
Apollo	O
workstations	B-Device
ran	O
Aegis	O
(	O
later	O
replaced	O
by	O
Domain/OS	B-Application
)	O
,	O
a	O
proprietary	O
operating	B-General_Concept
system	I-General_Concept
with	O
a	O
POSIX-compliant	O
Unix	B-Application
alternative	O
shell	B-Operating_System
.	O
</s>
<s>
Apollo	O
's	O
networking	O
was	O
particularly	O
elegant	O
,	O
among	O
the	O
first	O
to	O
allow	O
demand	B-General_Concept
paging	I-General_Concept
over	O
the	O
network	O
,	O
and	O
allowing	O
a	O
degree	O
of	O
network	O
transparency	O
and	O
low	O
sysadmin-to-machine	O
ratio	O
.	O
</s>
<s>
From	O
1980	O
to	O
1987	O
,	O
Apollo	O
was	O
the	O
largest	O
manufacturer	O
of	O
network	O
workstations	B-Device
.	O
</s>
<s>
Its	O
quarterly	O
sales	O
exceeded	O
$100	O
million	O
for	O
the	O
first	O
time	O
in	O
late	O
1986	O
,	O
and	O
by	O
the	O
end	O
of	O
that	O
year	O
,	O
it	O
had	O
the	O
largest	O
worldwide	O
share	O
of	O
the	O
engineering	O
workstations	B-Device
market	O
,	O
at	O
twice	O
the	O
market	O
share	O
of	O
the	O
number	O
two	O
,	O
Sun	O
Microsystems	O
.	O
</s>
<s>
But	O
after	O
acquiring	O
Apollo	O
Computer	O
in	O
1989	O
,	O
HP	O
integrated	O
a	O
lot	O
of	O
Apollo	O
technology	O
into	O
their	O
own	O
HP	B-Device
9000	I-Device
series	O
of	O
workstations	B-Device
and	O
servers	O
.	O
</s>
<s>
The	O
Apollo	O
engineering	O
center	O
took	O
over	O
PA-RISC	O
workstation	B-Device
development	O
and	O
Apollo	O
became	O
an	O
HP	O
workstation	B-Device
brand	O
name	O
(	O
HP	O
Apollo	O
9000	O
)	O
for	O
a	O
while	O
.	O
</s>
<s>
Apollo	O
also	O
invented	O
the	O
revision	B-Architecture
control	I-Architecture
system	I-Architecture
DSEE	O
(	O
Domain	B-Protocol
Software	I-Protocol
Engineering	I-Protocol
Environment	I-Protocol
)	O
which	O
inspired	O
IBM	B-Protocol
Rational	I-Protocol
ClearCase	I-Protocol
.	O
</s>
<s>
Apollo	O
machines	O
used	O
a	O
proprietary	O
operating	B-General_Concept
system	I-General_Concept
,	O
Aegis	O
,	O
because	O
of	O
the	O
excessive	O
cost	O
of	O
single-CPU	O
Unix	B-Application
licenses	O
at	O
the	O
time	O
of	O
system	O
definition	O
.	O
</s>
<s>
Aegis	O
,	O
like	O
Unix	B-Application
,	O
was	O
based	O
on	O
concepts	O
from	O
the	O
Multics	B-Application
time-sharing	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
It	O
used	O
the	O
concepts	O
of	O
shell	B-Operating_System
programming	O
( à	O
la	O
Stephen	O
Bourne	O
)	O
,	O
single-level	B-Device
store	I-Device
,	O
and	O
object-oriented	B-Application
design	I-Application
.	O
</s>
<s>
Aegis	O
was	O
written	O
in	O
a	O
proprietary	O
version	O
of	O
Pascal	B-Application
.	O
</s>
<s>
The	O
dual	O
68000	B-Device
processor	O
configuration	O
was	O
designed	O
to	O
provide	O
automatic	O
page	B-General_Concept
fault	I-General_Concept
switching	O
,	O
with	O
the	O
main	O
processor	O
executing	O
the	O
OS	O
and	O
program	O
instructions	O
,	O
and	O
the	O
"	O
fixer	O
"	O
processor	O
satisfying	O
the	O
page	B-General_Concept
faults	I-General_Concept
.	O
</s>
<s>
When	O
a	O
page	B-General_Concept
fault	I-General_Concept
was	O
raised	O
,	O
the	O
main	O
CPU	O
was	O
halted	O
in	O
mid	O
(	O
memory	O
)	O
cycle	O
while	O
the	O
fixer	O
CPU	O
would	O
bring	O
the	O
page	O
into	O
memory	O
and	O
then	O
allow	O
the	O
main	O
CPU	O
to	O
continue	O
,	O
unaware	O
of	O
the	O
page	B-General_Concept
fault	I-General_Concept
.	O
</s>
<s>
Later	O
improvements	O
in	O
the	O
Motorola	B-Device
68010	I-Device
processor	O
obviated	O
the	O
need	O
for	O
the	O
dual-processor	O
design	O
.	O
</s>
<s>
With	O
this	O
arrangement	O
,	O
a	O
page	B-General_Concept
fault	I-General_Concept
could	O
take	O
place	O
across	O
the	O
network	O
as	O
well	O
as	O
on	O
the	O
individual	O
computer	O
and	O
Aegis	O
file	O
system	O
was	O
a	O
single	O
system	O
of	O
memory	B-General_Concept
mapped	I-General_Concept
files	I-General_Concept
across	O
the	O
entire	O
network	O
.	O
</s>
<s>
The	O
namespace	O
of	O
the	O
network	O
was	O
self	O
discovering	O
as	O
new	O
nodes	O
(	O
workstations	B-Device
)	O
were	O
added	O
.	O
</s>
<s>
Domain/OS	B-Application
(	O
Distributed	O
On-line	O
Multi-access	O
Interactive	O
Network/Operating	O
System	O
)	O
was	O
initially	O
a	O
layer	O
over	O
Aegis	O
and	O
was	O
not	O
built	O
on	O
a	O
Unix	B-Application
kernel	O
.	O
</s>
<s>
Release	O
10	O
incorporated	O
large	O
parts	O
of	O
Unix	B-Application
but	O
the	O
burden	O
of	O
backwards	O
compatibility	O
with	O
previous	O
releases	O
led	O
to	O
a	O
system	O
that	O
was	O
larger	O
and	O
significantly	O
slower	O
than	O
the	O
previous	O
ones	O
.	O
</s>
<s>
In	O
the	O
end	O
,	O
Hewlett	O
Packard	O
shut	O
down	O
the	O
Domain/OS	B-Application
line	O
.	O
</s>
<s>
Release	O
10	O
came	O
out	O
as	O
competitors	O
were	O
gaining	O
ground	O
in	O
the	O
area	O
of	O
graphics	O
and	O
windowing	O
systems	O
,	O
particularly	O
with	O
the	O
trend	O
to	O
open	B-Operating_System
systems	I-Operating_System
and	O
the	O
X	B-Operating_System
Window	I-Operating_System
System	I-Operating_System
.	O
</s>
<s>
Another	O
feature	O
was	O
its	O
proprietary	O
token	B-Protocol
ring	I-Protocol
network	O
,	O
which	O
was	O
originally	O
designed	O
to	O
support	O
relatively	O
small	O
networks	O
of	O
,	O
at	O
most	O
,	O
dozens	O
of	O
computers	O
in	O
an	O
office	O
environment	O
.	O
</s>
<s>
It	O
was	O
a	O
superb	O
design	O
,	O
allowing	O
direct	B-General_Concept
memory	I-General_Concept
access	I-General_Concept
page	O
faulting	O
from	O
any	O
hard	B-Device
drive	I-Device
on	O
the	O
network	O
,	O
but	O
it	O
did	O
not	O
inter-operate	O
with	O
any	O
other	O
existing	O
network	O
hardware	O
or	O
software	O
.	O
</s>
<s>
The	O
industry	O
widely	O
adopted	O
Ethernet	O
and	O
TCP/IP	B-Protocol
,	O
a	O
more	O
universal	O
,	O
albeit	O
much	O
slower	O
network	O
.	O
</s>
<s>
Apollo	O
later	O
added	O
support	O
for	O
these	O
industry	O
standards	O
while	O
continuing	O
to	O
support	O
its	O
own	O
Domain	B-Device
networking	O
using	O
both	O
Ethernet	O
and	O
token	B-Protocol
ring	I-Protocol
.	O
</s>
<s>
The	O
Domain	B-Device
network	O
routing	O
was	O
modeled	O
after	O
Xerox	B-Protocol
Network	I-Protocol
Systems	I-Protocol
.	O
</s>
<s>
The	O
company	O
moved	O
from	O
a	O
proprietary	O
data	O
bus	O
architecture	O
in	O
favor	O
of	O
IBM	O
's	O
AT-bus	B-Architecture
,	O
as	O
used	O
in	O
the	O
second	O
generation	O
of	O
IBM	B-Device
PCs	I-Device
,	O
and	O
was	O
simultaneously	O
embracing	O
RISC	B-Architecture
technology	O
moving	O
towards	O
high-end	O
processors	O
,	O
eventually	O
producing	O
the	O
PRISM	B-General_Concept
line	O
.	O
</s>
<s>
The	O
workstation	B-Device
industry	O
in	O
general	O
experienced	O
hard	O
times	O
in	O
the	O
second	O
half	O
of	O
the	O
1980s	O
,	O
as	O
IBM	B-Device
Personal	I-Device
Computers	I-Device
and	O
IBM	B-Device
PC	I-Device
compatibles	O
began	O
making	O
inroads	O
on	O
their	O
customer	O
base	O
.	O
</s>
<s>
Earlier	O
that	O
year	O
,	O
Sun	O
had	O
already	O
offered	O
discounts	O
on	O
its	O
systems	O
for	O
customers	O
trading	O
in	O
their	O
Apollo	O
machines	O
;	O
HP	O
responded	O
the	O
next	O
winter	O
with	O
a	O
trade-in	O
program	O
of	O
its	O
own	O
,	O
that	O
also	O
allowed	O
trading	O
in	O
hardware	O
from	O
Sun	O
and	O
other	O
vendors	O
in	O
return	O
for	O
a	O
discount	O
on	O
HP	O
workstations	B-Device
.	O
</s>
