<s>
The	O
PDP-11	B-Device
is	O
a	O
series	O
of	O
16-bit	B-Device
minicomputers	B-Architecture
sold	O
by	O
Digital	O
Equipment	O
Corporation	O
(	O
DEC	O
)	O
from	O
1970	O
into	O
the	O
late	O
1990s	O
,	O
one	O
of	O
a	O
set	O
of	O
products	O
in	O
the	O
Programmed	B-Device
Data	I-Device
Processor	I-Device
(	O
PDP	O
)	O
series	O
.	O
</s>
<s>
In	O
total	O
,	O
around	O
600,000	O
PDP-11s	B-Device
of	O
all	O
models	O
were	O
sold	O
,	O
making	O
it	O
one	O
of	O
DEC	O
's	O
most	O
successful	O
product	O
lines	O
.	O
</s>
<s>
The	O
PDP-11	B-Device
is	O
considered	O
by	O
some	O
experts	O
to	O
be	O
the	O
most	O
popular	O
minicomputer	B-Architecture
.	O
</s>
<s>
The	O
PDP-11	B-Device
included	O
a	O
number	O
of	O
innovative	O
features	O
in	O
its	O
instruction	B-General_Concept
set	I-General_Concept
and	O
additional	O
general-purpose	O
registers	B-General_Concept
that	O
made	O
it	O
easier	O
to	O
program	O
than	O
earlier	O
models	O
in	O
the	O
PDP	O
series	O
.	O
</s>
<s>
Further	O
,	O
the	O
innovative	O
Unibus	B-Device
system	O
allowed	O
external	O
devices	O
to	O
be	O
more	O
easily	O
interfaced	O
to	O
the	O
system	O
using	O
direct	B-General_Concept
memory	I-General_Concept
access	I-General_Concept
,	O
opening	O
the	O
system	O
to	O
a	O
wide	O
variety	O
of	O
peripherals	O
.	O
</s>
<s>
The	O
PDP-11	B-Device
replaced	O
the	O
PDP-8	B-Device
in	O
many	O
real-time	B-General_Concept
computing	I-General_Concept
applications	O
,	O
although	O
both	O
product	O
lines	O
lived	O
in	O
parallel	O
for	O
more	O
than	O
10	O
years	O
.	O
</s>
<s>
The	O
ease	O
of	O
programming	O
of	O
the	O
PDP-11	B-Device
made	O
it	O
popular	O
for	O
general-purpose	O
computing	O
.	O
</s>
<s>
The	O
design	O
of	O
the	O
PDP-11	B-Device
inspired	O
the	O
design	O
of	O
late-1970s	O
microprocessors	B-Architecture
including	O
the	O
Intel	B-Operating_System
x86	I-Operating_System
and	O
the	O
Motorola	B-Device
68000	I-Device
.	O
</s>
<s>
The	O
design	O
features	O
of	O
PDP-11	B-Device
operating	B-General_Concept
systems	I-General_Concept
,	O
and	O
other	O
operating	B-General_Concept
systems	I-General_Concept
from	O
Digital	O
Equipment	O
,	O
influenced	O
the	O
design	O
of	O
operating	B-General_Concept
systems	I-General_Concept
such	O
as	O
CP/M	B-Application
and	O
hence	O
also	O
MS-DOS	B-Application
.	O
</s>
<s>
The	O
first	O
officially	O
named	O
version	O
of	O
Unix	B-Application
ran	O
on	O
the	O
PDP-11/20	O
in	O
1970	O
.	O
</s>
<s>
It	O
is	O
commonly	O
stated	O
that	O
the	O
C	B-Language
programming	I-Language
language	I-Language
took	O
advantage	O
of	O
several	O
low-level	O
PDP-11	B-Device
–	O
dependent	O
programming	O
features	O
,	O
albeit	O
not	O
originally	O
by	O
design	O
.	O
</s>
<s>
An	O
effort	O
to	O
expand	O
the	O
PDP-11	B-Device
from	O
16	O
-	O
to	O
32-bit	O
addressing	O
led	O
to	O
the	O
VAX-11	B-Device
design	O
,	O
which	O
took	O
part	O
of	O
its	O
name	O
from	O
the	O
PDP-11	B-Device
.	O
</s>
<s>
In	O
1963	O
,	O
DEC	O
introduced	O
what	O
is	O
considered	O
to	O
be	O
the	O
first	O
commercial	O
minicomputer	B-Architecture
in	O
the	O
form	O
of	O
the	O
PDP-5	B-Device
.	O
</s>
<s>
This	O
was	O
a	O
12-bit	O
design	O
adapted	O
from	O
the	O
1962	O
LINC	B-Device
machine	O
that	O
was	O
intended	O
to	O
be	O
used	O
in	O
a	O
lab	O
setting	O
.	O
</s>
<s>
DEC	O
slightly	O
simplified	O
the	O
LINC	B-Device
system	O
and	O
instruction	B-General_Concept
set	I-General_Concept
,	O
aiming	O
the	O
PDP-5	B-Device
at	O
smaller	O
settings	O
that	O
did	O
not	O
need	O
the	O
power	O
of	O
their	O
larger	O
18-bit	O
PDP-4	B-Device
.	O
</s>
<s>
The	O
PDP-5	B-Device
was	O
a	O
success	O
,	O
ultimately	O
selling	O
about	O
1,000	O
machines	O
.	O
</s>
<s>
This	O
led	O
to	O
the	O
PDP-8	B-Device
,	O
a	O
further	O
cost-reduced	O
12-bit	O
model	O
that	O
sold	O
about	O
50,000	O
units	O
.	O
</s>
<s>
During	O
this	O
period	O
,	O
the	O
computer	O
market	O
was	O
moving	O
from	O
computer	O
word	O
lengths	O
based	O
on	O
units	O
of	O
6	O
bits	O
to	O
units	O
of	O
8	O
bits	O
,	O
following	O
the	O
introduction	O
of	O
the	O
7-bit	B-Protocol
ASCII	I-Protocol
standard	O
.	O
</s>
<s>
In	O
1967	O
–	O
1968	O
,	O
DEC	O
engineers	O
designed	O
a	O
16-bit	B-Device
machine	O
,	O
the	O
PDP-X	O
,	O
but	O
management	O
ultimately	O
canceled	O
the	O
project	O
as	O
it	O
did	O
not	O
appear	O
to	O
offer	O
a	O
significant	O
advantage	O
over	O
their	O
existing	O
12	O
-	O
and	O
18-bit	O
platforms	O
.	O
</s>
<s>
The	O
next	O
year	O
they	O
introduced	O
the	O
16-bit	B-Device
Data	B-Device
General	I-Device
Nova	I-Device
.	O
</s>
<s>
Ken	O
Olsen	O
,	O
president	O
and	O
founder	O
of	O
DEC	O
,	O
was	O
more	O
interested	O
in	O
a	O
small	O
8-bit	O
machine	O
than	O
the	O
larger	O
16-bit	B-Device
system	O
.	O
</s>
<s>
Before	O
long	O
,	O
it	O
became	O
clear	O
that	O
the	O
entire	O
market	O
was	O
moving	O
to	O
16-bit	B-Device
,	O
and	O
the	O
Desk	O
Calculator	O
began	O
a	O
16-bit	B-Device
design	O
as	O
well	O
.	O
</s>
<s>
Larry	O
McGowan	O
coded	O
a	O
series	O
of	O
assembly	B-Language
language	I-Language
programs	O
using	O
the	O
instruction	B-General_Concept
sets	I-General_Concept
of	O
various	O
existing	O
platforms	O
and	O
examined	O
how	O
much	O
memory	O
would	O
be	O
exchanged	O
to	O
execute	O
them	O
.	O
</s>
<s>
Harold	O
McFarland	O
joined	O
the	O
effort	O
and	O
had	O
already	O
written	O
a	O
very	O
complex	O
instruction	B-General_Concept
set	I-General_Concept
that	O
the	O
team	O
rejected	O
,	O
but	O
a	O
second	O
one	O
was	O
simpler	O
and	O
would	O
ultimately	O
form	O
the	O
basis	O
for	O
the	O
PDP-11	B-Device
.	O
</s>
<s>
Much	O
of	O
the	O
system	O
was	O
developed	O
using	O
a	O
PDP-10	B-Device
where	O
the	O
SIM-11	O
simulated	O
what	O
would	O
become	O
the	O
PDP-11/20	O
and	O
Bob	O
Bowers	O
wrote	O
an	O
assembler	B-Language
for	O
it	O
.	O
</s>
<s>
When	O
McGowan	O
stated	O
this	O
would	O
mean	O
an	O
assembler	B-Language
could	O
not	O
run	O
on	O
the	O
system	O
,	O
the	O
minimum	O
was	O
expanded	O
to	O
4K	O
.	O
</s>
<s>
The	O
marketing	O
team	O
also	O
wanted	O
to	O
use	O
the	O
forward	O
slash	O
character	O
for	O
comments	O
in	O
the	O
assembler	B-Language
code	I-Language
,	O
as	O
was	O
the	O
case	O
in	O
the	O
PDP-8	B-Device
assembler	B-Language
.	O
</s>
<s>
The	O
PDP-11	B-Device
family	O
was	O
announced	O
in	O
January	O
1970	O
and	O
shipments	O
began	O
early	O
that	O
year	O
.	O
</s>
<s>
DEC	O
sold	O
over	O
170,000	O
PDP-11s	B-Device
in	O
the	O
1970s	O
.	O
</s>
<s>
Initially	O
manufactured	O
of	O
small-scale	O
transistor	B-General_Concept
–	I-General_Concept
transistor	I-General_Concept
logic	I-General_Concept
,	O
a	O
single-board	O
large	O
scale	O
integration	O
version	O
of	O
the	O
processor	O
was	O
developed	O
in	O
1975	O
.	O
</s>
<s>
A	O
two	O
-	O
or	O
three-chip	O
processor	O
,	O
the	O
J-11	B-Device
was	O
developed	O
in	O
1979	O
.	O
</s>
<s>
The	O
last	O
models	O
of	O
the	O
PDP-11	B-Device
line	O
were	O
the	O
single	O
board	O
PDP-11/94	O
and	O
PDP-11/93	O
introduced	O
in	O
1990	O
.	O
</s>
<s>
The	O
PDP-11	B-Device
processor	O
architecture	O
has	O
a	O
mostly	O
orthogonal	B-General_Concept
instruction	I-General_Concept
set	I-General_Concept
.	O
</s>
<s>
For	O
example	O
,	O
instead	O
of	O
instructions	O
such	O
as	O
load	O
and	O
store	O
,	O
the	O
PDP-11	B-Device
has	O
a	O
move	O
instruction	O
for	O
which	O
either	O
operand	O
(	O
source	O
and	O
destination	O
)	O
can	O
be	O
memory	O
or	O
register	O
.	O
</s>
<s>
There	O
are	O
no	O
specific	O
input	O
or	O
output	O
instructions	O
;	O
the	O
PDP-11	B-Device
uses	O
memory-mapped	B-Architecture
I/O	I-Architecture
and	O
so	O
the	O
same	O
move	O
instruction	O
is	O
used	O
;	O
orthogonality	O
even	O
enables	O
moving	O
data	O
directly	O
from	O
an	O
input	O
device	O
to	O
an	O
output	O
device	O
.	O
</s>
<s>
Most	O
operands	O
can	O
apply	O
any	O
of	O
eight	O
addressing	O
modes	O
to	O
eight	O
registers	B-General_Concept
.	O
</s>
<s>
Use	O
of	O
relative	O
addressing	O
lets	O
a	O
machine-language	O
program	O
be	O
position-independent	B-Operating_System
.	O
</s>
<s>
Early	O
models	O
of	O
the	O
PDP-11	B-Device
had	O
no	O
dedicated	O
bus	B-General_Concept
for	O
input/output	B-General_Concept
,	O
but	O
only	O
a	O
system	B-Architecture
bus	I-Architecture
called	O
the	O
Unibus	B-Device
,	O
as	O
input	B-General_Concept
and	I-General_Concept
output	I-General_Concept
devices	O
were	O
mapped	O
to	O
memory	O
addresses	O
.	O
</s>
<s>
An	O
input/output	B-General_Concept
device	I-General_Concept
determined	O
the	O
memory	O
addresses	O
to	O
which	O
it	O
would	O
respond	O
,	O
and	O
specified	O
its	O
own	O
interrupt	B-General_Concept
vector	I-General_Concept
and	O
interrupt	B-Operating_System
priority	I-Operating_System
.	O
</s>
<s>
This	O
flexible	O
framework	O
provided	O
by	O
the	O
processor	O
architecture	O
made	O
it	O
unusually	O
easy	O
to	O
invent	O
new	O
bus	B-General_Concept
devices	O
,	O
including	O
devices	O
to	O
control	O
hardware	O
that	O
had	O
not	O
been	O
contemplated	O
when	O
the	O
processor	O
was	O
originally	O
designed	O
.	O
</s>
<s>
DEC	O
openly	O
published	O
the	O
basic	O
Unibus	B-Device
specifications	O
,	O
even	O
offering	O
prototyping	O
bus	B-General_Concept
interface	O
circuit	O
boards	O
,	O
and	O
encouraging	O
customers	O
to	O
develop	O
their	O
own	O
Unibus-compatible	O
hardware	O
.	O
</s>
<s>
The	O
Unibus	B-Device
made	O
the	O
PDP-11	B-Device
suitable	O
for	O
custom	O
peripherals	O
.	O
</s>
<s>
One	O
of	O
the	O
predecessors	O
of	O
Alcatel-Lucent	O
,	O
the	O
Bell	O
Telephone	O
Manufacturing	O
Company	O
,	O
developed	O
the	O
BTMC	O
DPS-1500	O
packet-switching	O
(	O
X.25	B-Protocol
)	O
network	O
and	O
used	O
PDP-11s	B-Device
in	O
the	O
regional	O
and	O
national	O
network	O
management	O
system	O
,	O
with	O
the	O
Unibus	B-Device
directly	O
connected	O
to	O
the	O
DPS-1500	O
hardware	O
.	O
</s>
<s>
Higher-performance	O
members	O
of	O
the	O
PDP-11	B-Device
family	O
departed	O
from	O
the	O
single-bus	O
approach	O
.	O
</s>
<s>
The	O
PDP-11/45	B-Device
had	O
a	O
dedicated	O
data	O
path	O
within	O
the	O
CPU	B-General_Concept
,	O
connecting	O
semiconductor	O
memory	O
to	O
the	O
processor	O
,	O
with	O
core	O
memory	O
and	O
I/O	B-General_Concept
devices	I-General_Concept
connected	O
via	O
the	O
Unibus	B-Device
.	O
</s>
<s>
In	O
the	O
PDP-11/70	B-Device
,	O
this	O
was	O
taken	O
a	O
step	O
further	O
,	O
with	O
the	O
addition	O
of	O
a	O
dedicated	O
interface	O
between	O
disks	O
and	O
tapes	O
and	O
memory	O
,	O
via	O
the	O
Massbus	B-Architecture
.	O
</s>
<s>
Although	O
input/output	B-General_Concept
devices	I-General_Concept
continued	O
to	O
be	O
mapped	O
into	O
memory	O
addresses	O
,	O
some	O
additional	O
programming	O
was	O
necessary	O
to	O
set	O
up	O
the	O
added	O
bus	B-General_Concept
interfaces	O
.	O
</s>
<s>
The	O
PDP-11	B-Device
supports	O
hardware	O
interrupts	B-Application
at	O
four	O
priority	O
levels	O
.	O
</s>
<s>
Interrupts	B-Application
are	O
serviced	O
by	O
software	O
service	O
routines	O
,	O
which	O
could	O
specify	O
whether	O
they	O
themselves	O
could	O
be	O
interrupted	O
(	O
achieving	O
interrupt	B-Application
nesting	B-General_Concept
)	O
.	O
</s>
<s>
The	O
event	O
that	O
causes	O
the	O
interrupt	B-Application
is	O
indicated	O
by	O
the	O
device	O
itself	O
,	O
as	O
it	O
informs	O
the	O
processor	O
of	O
the	O
address	O
of	O
its	O
own	O
interrupt	B-General_Concept
vector	I-General_Concept
.	O
</s>
<s>
Interrupt	B-General_Concept
vectors	I-General_Concept
are	O
blocks	O
of	O
two	O
16-bit	B-Device
words	O
in	O
low	O
kernel	O
address	O
space	O
(	O
which	O
normally	O
corresponded	O
to	O
low	O
physical	O
memory	O
)	O
between	O
0	O
and	O
776	O
.	O
</s>
<s>
The	O
first	O
word	O
of	O
the	O
interrupt	B-General_Concept
vector	I-General_Concept
contains	O
the	O
address	O
of	O
the	O
interrupt	B-Application
service	O
routine	O
and	O
the	O
second	O
word	O
the	O
value	O
to	O
be	O
loaded	O
into	O
the	O
PSW	O
(	O
priority	O
level	O
)	O
on	O
entry	O
to	O
the	O
service	O
routine	O
.	O
</s>
<s>
The	O
PDP-11	B-Device
was	O
designed	O
for	O
ease	O
of	O
manufacture	O
by	O
semiskilled	O
labor	O
.	O
</s>
<s>
It	O
used	O
a	O
wire-wrapped	O
backplane	B-Architecture
.	O
</s>
<s>
The	O
LSI-11	O
(	O
PDP-11/03	O
)	O
,	O
introduced	O
in	O
February	O
1975	O
is	O
the	O
first	O
PDP-11	B-Device
model	O
produced	O
using	O
large-scale	O
integration	O
;	O
the	O
entire	O
CPU	B-General_Concept
is	O
contained	O
on	O
four	O
LSI	O
chips	O
made	O
by	O
Western	O
Digital	O
(	O
the	O
MCP-1600	B-General_Concept
chip	O
set	O
;	O
a	O
fifth	O
chip	O
can	O
be	O
added	O
to	O
extend	O
the	O
instruction	B-General_Concept
set	I-General_Concept
)	O
.	O
</s>
<s>
It	O
uses	O
a	O
bus	B-General_Concept
which	O
is	O
a	O
close	O
variant	O
of	O
the	O
Unibus	B-Device
called	O
the	O
LSI	O
Bus	B-General_Concept
or	O
Q-Bus	B-Architecture
;	O
it	O
differs	O
from	O
the	O
Unibus	B-Device
primarily	O
in	O
that	O
addresses	O
and	O
data	O
are	O
multiplexed	O
onto	O
a	O
shared	O
set	O
of	O
wires	O
rather	O
than	O
having	O
separate	O
sets	O
of	O
wires	O
.	O
</s>
<s>
It	O
also	O
differs	O
slightly	O
in	O
how	O
it	O
addresses	O
I/O	B-General_Concept
devices	I-General_Concept
and	O
it	O
eventually	O
allowed	O
a	O
22-bit	O
physical	O
address	O
(	O
whereas	O
the	O
Unibus	B-Device
only	O
allows	O
an	O
18-bit	O
physical	O
address	O
)	O
and	O
block-mode	O
operations	O
for	O
significantly	O
improved	O
bandwidth	O
(	O
which	O
the	O
Unibus	B-Device
does	O
not	O
support	O
)	O
.	O
</s>
<s>
The	O
CPU	B-General_Concept
microcode	B-Device
includes	O
a	O
debugger	B-Application
:	O
firmware	O
with	O
a	O
direct	O
serial	B-Protocol
interface	I-Protocol
(	O
RS-232	O
or	O
current	O
loop	O
)	O
to	O
a	O
terminal	B-General_Concept
.	O
</s>
<s>
The	O
operator	O
can	O
thus	O
examine	O
and	O
modify	O
the	O
computer	O
's	O
registers	B-General_Concept
,	O
memory	O
,	O
and	O
input/output	B-General_Concept
devices	I-General_Concept
,	O
diagnosing	O
and	O
perhaps	O
correcting	O
failures	O
in	O
software	O
and	O
peripherals	O
(	O
unless	O
a	O
failure	O
disables	O
the	O
microcode	B-Device
itself	O
)	O
.	O
</s>
<s>
The	O
operator	O
can	O
also	O
specify	O
which	O
disk	O
to	O
boot	B-Operating_System
from	O
.	O
</s>
<s>
This	O
option	O
allowed	O
programming	O
of	O
the	O
internal	O
8-bit	O
micromachine	O
to	O
create	O
application-specific	O
extensions	O
to	O
the	O
PDP-11	B-Device
instruction	B-General_Concept
set	I-General_Concept
.	O
</s>
<s>
The	O
WCS	O
is	O
a	O
quad	O
Q-Bus	B-Architecture
board	O
with	O
a	O
ribbon	O
cable	O
connecting	O
to	O
the	O
third	O
microcode	B-Device
ROM	O
socket	O
.	O
</s>
<s>
The	O
source	O
code	O
for	O
EIS/FIS	O
microcode	B-Device
was	O
included	O
so	O
these	O
instructions	O
,	O
normally	O
located	O
in	O
the	O
third	O
MICROM	O
,	O
could	O
be	O
loaded	O
in	O
the	O
WCS	O
,	O
if	O
desired	O
.	O
</s>
<s>
Later	O
Q-Bus	B-Architecture
based	O
systems	O
such	O
as	O
the	O
LSI-11/23	O
,	O
/73	O
,	O
and	O
/83	O
are	O
based	O
upon	O
chip	O
sets	O
designed	O
in	O
house	O
by	O
Digital	O
Equipment	O
Corporation	O
.	O
</s>
<s>
Later	O
PDP-11	B-Device
Unibus	B-Device
systems	O
were	O
designed	O
to	O
use	O
similar	O
Q-Bus	B-Architecture
processor	O
cards	O
,	O
using	O
a	O
Unibus	B-Device
adapter	O
to	O
support	O
existing	O
Unibus	B-Device
peripherals	O
,	O
sometimes	O
with	O
a	O
special	O
memory	O
bus	B-General_Concept
for	O
improved	O
speed	O
.	O
</s>
<s>
There	O
were	O
other	O
significant	O
innovations	O
in	O
the	O
Q-Bus	B-Architecture
lineup	O
.	O
</s>
<s>
For	O
example	O
,	O
a	O
system	O
variant	O
of	O
the	O
PDP-11/03	O
introduced	O
full	O
system	O
power-on	B-Device
self-test	I-Device
(	O
POST	O
)	O
.	O
</s>
<s>
The	O
basic	O
design	O
of	O
the	O
PDP-11	B-Device
was	O
flexible	O
,	O
and	O
was	O
continually	O
updated	O
to	O
use	O
newer	O
technologies	O
.	O
</s>
<s>
However	O
,	O
the	O
limited	O
throughput	O
of	O
the	O
Unibus	B-Device
and	O
Q-Bus	B-Architecture
started	O
to	O
become	O
a	O
system-performance	O
bottleneck	O
,	O
and	O
the	O
16-bit	B-Device
logical	O
address	O
limitation	O
hampered	O
the	O
development	O
of	O
larger	O
software	O
applications	O
.	O
</s>
<s>
The	O
article	O
on	O
PDP-11	B-Device
architecture	O
describes	O
the	O
hardware	O
and	O
software	O
techniques	O
used	O
to	O
work	O
around	O
address-space	O
limitations	O
.	O
</s>
<s>
DEC	O
's	O
32-bit	O
successor	O
to	O
the	O
PDP-11	B-Device
,	O
the	O
VAX-11	B-Device
(	O
for	O
"	O
Virtual	O
Address	O
eXtension	O
"	O
)	O
overcame	O
the	O
16-bit	B-Device
limitation	O
,	O
but	O
was	O
initially	O
a	O
superminicomputer	B-Device
aimed	O
at	O
the	O
high-end	O
time-sharing	B-General_Concept
market	O
.	O
</s>
<s>
The	O
early	O
VAX	B-Device
CPUs	O
provided	O
a	O
PDP-11	B-Device
compatibility	B-Application
mode	I-Application
under	O
which	O
much	O
existing	O
software	O
could	O
be	O
immediately	O
used	O
,	O
in	O
parallel	O
with	O
newer	O
32-bit	O
software	O
,	O
but	O
this	O
capability	O
was	O
dropped	O
with	O
the	O
first	O
MicroVAX	B-Device
.	O
</s>
<s>
For	O
a	O
decade	O
,	O
the	O
PDP-11	B-Device
was	O
the	O
smallest	O
system	O
that	O
could	O
run	O
Unix	B-Application
,	O
but	O
in	O
the	O
1980s	O
,	O
the	O
IBM	B-Device
PC	I-Device
and	O
its	O
clones	O
largely	O
took	O
over	O
the	O
small	O
computer	O
market	O
;	O
BYTE	O
in	O
1984	O
reported	O
that	O
the	O
PC	O
's	O
Intel	B-Device
8088	I-Device
microprocessor	B-Architecture
could	O
outperform	O
the	O
PDP-11/23	O
when	O
running	O
Unix	B-Application
.	O
</s>
<s>
Newer	O
microprocessors	B-Architecture
such	O
as	O
the	O
Motorola	B-Device
68000	I-Device
(	O
1979	O
)	O
and	O
Intel	B-General_Concept
80386	I-General_Concept
(	O
1985	O
)	O
also	O
included	O
32-bit	O
logical	O
addressing	O
.	O
</s>
<s>
The	O
68000	B-Device
in	O
particular	O
facilitated	O
the	O
emergence	O
of	O
a	O
market	O
of	O
increasingly	O
powerful	O
scientific	O
and	O
technical	O
workstations	B-Device
that	O
would	O
often	O
run	O
Unix	B-Application
variants	O
.	O
</s>
<s>
These	O
included	O
the	O
HP	B-Device
9000	I-Device
series	O
200	O
(	O
starting	O
with	O
the	O
HP	O
9826A	O
in	O
1981	O
)	O
and	O
300/400	O
,	O
with	O
the	O
HP-UX	B-Application
system	O
being	O
ported	O
to	O
the	O
68000	B-Device
in	O
1984	O
;	O
Sun	O
Microsystems	O
workstations	B-Device
running	O
SunOS	B-Operating_System
,	O
starting	O
with	O
the	O
Sun-1	B-Device
in	O
1982	O
;	O
Apollo/Domain	B-Device
workstations	B-Device
starting	O
with	O
the	O
DN100	O
in	O
1981	O
running	O
Domain/OS	B-Application
,	O
which	O
was	O
proprietary	O
but	O
offered	O
a	O
degree	O
of	O
Unix	B-Application
compatibility	O
;	O
and	O
the	O
Silicon	O
Graphics	O
IRIS	B-Device
range	O
,	O
which	O
developed	O
into	O
Unix-based	O
workstations	B-Device
by	O
1985	O
(	O
IRIS	B-Device
2000	O
)	O
.	O
</s>
<s>
Personal	O
computers	O
based	O
on	O
the	O
68000	B-Device
such	O
as	O
the	O
Apple	B-Device
Lisa	I-Device
and	O
Macintosh	B-Device
,	O
the	O
Atari	B-Device
ST	I-Device
,	O
and	O
the	O
Commodore	B-Device
Amiga	I-Device
arguably	O
constituted	O
less	O
of	O
a	O
threat	O
to	O
DEC	O
's	O
business	O
,	O
although	O
technically	O
these	O
systems	O
could	O
also	O
run	O
Unix	B-Application
derivatives	O
.	O
</s>
<s>
In	O
the	O
early	O
years	O
,	O
in	O
particular	O
,	O
Microsoft	O
's	O
Xenix	B-Application
was	O
ported	O
to	O
systems	O
like	O
the	O
TRS-80	O
Model	O
16	O
(	O
with	O
up	O
to	O
1	O
MB	O
of	O
memory	O
)	O
in	O
1983	O
,	O
and	O
to	O
the	O
Apple	B-Device
Lisa	I-Device
,	O
with	O
up	O
to	O
2	O
MB	O
of	O
installed	O
RAM	O
,	O
in	O
1984	O
.	O
</s>
<s>
The	O
mass-production	O
of	O
those	O
chips	O
eliminated	O
any	O
cost	O
advantage	O
for	O
the	O
16-bit	B-Device
PDP-11	B-Device
.	O
</s>
<s>
A	O
line	O
of	O
personal	O
computers	O
based	O
on	O
the	O
PDP-11	B-Device
,	O
the	O
DEC	B-Device
Professional	I-Device
series	I-Device
,	O
failed	O
commercially	O
,	O
along	O
with	O
other	O
non-PDP-11	O
PC	O
offerings	O
from	O
DEC	O
.	O
</s>
<s>
In	O
1994	O
,	O
DEC	O
sold	O
the	O
PDP-11	B-Device
system-software	O
rights	O
to	O
Mentec	O
Inc.	O
,	O
an	O
Irish	O
producer	O
of	O
LSI-11	O
based	O
boards	O
for	O
Q-Bus	B-Architecture
and	O
ISA	O
architecture	O
personal	O
computers	O
,	O
and	O
in	O
1997	O
discontinued	O
PDP-11	B-Device
production	O
.	O
</s>
<s>
For	O
several	O
years	O
,	O
Mentec	O
produced	O
new	O
PDP-11	B-Device
processors	O
.	O
</s>
<s>
Other	O
companies	O
found	O
a	O
niche	O
market	O
for	O
replacements	O
for	O
legacy	O
PDP-11	B-Device
processors	O
,	O
disk	B-Device
subsystems	I-Device
,	O
etc	O
.	O
</s>
<s>
At	O
the	O
same	O
time	O
,	O
free	O
implementations	O
of	O
Unix	B-Application
for	O
the	O
PC	O
based	O
on	O
BSD	B-Operating_System
or	O
Linux	B-Application
became	O
available	O
.	O
</s>
<s>
By	O
the	O
late	O
1990s	O
,	O
not	O
only	O
DEC	O
but	O
most	O
of	O
the	O
New	O
England	O
computer	O
industry	O
which	O
had	O
been	O
built	O
around	O
minicomputers	B-Architecture
similar	O
to	O
the	O
PDP-11	B-Device
collapsed	O
in	O
the	O
face	O
of	O
microcomputer-based	O
workstations	B-Device
and	O
servers	O
.	O
</s>
<s>
The	O
PDP-11	B-Device
processors	O
tend	O
to	O
fall	O
into	O
several	O
natural	O
groups	O
depending	O
on	O
the	O
original	O
design	O
upon	O
which	O
they	O
are	O
based	O
and	O
which	O
I/O	B-General_Concept
bus	I-General_Concept
they	O
use	O
.	O
</s>
<s>
Although	O
all	O
models	O
share	O
the	O
same	O
instruction	B-General_Concept
set	I-General_Concept
,	O
later	O
models	O
added	O
new	O
instructions	O
and	O
interpreted	O
certain	O
instructions	O
slightly	O
differently	O
.	O
</s>
<s>
As	O
the	O
architecture	O
evolved	O
,	O
there	O
were	O
also	O
variations	O
in	O
handling	O
of	O
some	O
processor	O
status	O
and	O
control	O
registers	B-General_Concept
.	O
</s>
<s>
The	O
following	O
models	O
use	O
the	O
Unibus	B-Device
as	O
their	O
principal	O
bus	B-General_Concept
:	O
</s>
<s>
PDP-11/20	O
and	O
PDP-11/15	O
–	O
1970	O
.	O
</s>
<s>
Floating	B-Algorithm
point	I-Algorithm
is	O
supported	O
by	O
peripheral	O
options	O
using	O
various	O
data	O
formats	O
.	O
</s>
<s>
The	O
11/20	O
lacks	O
any	O
kind	O
of	O
memory	B-General_Concept
protection	I-General_Concept
hardware	O
unless	O
retrofitted	O
with	O
a	O
KS-11	O
memory	B-Architecture
mapping	I-Architecture
add-on	O
.	O
</s>
<s>
PDP-11/45	B-Device
(	O
1972	O
)	O
,	O
PDP-11/50	O
(	O
1975	O
)	O
,	O
and	O
PDP-11/55	O
(	O
1976	O
)	O
–	O
A	O
much	O
faster	O
microprogrammed	O
processor	O
that	O
can	O
use	O
up	O
to	O
256KB	O
of	O
semiconductor	O
memory	O
instead	O
of	O
or	O
in	O
addition	O
to	O
core	O
memory	O
and	O
support	O
memory	B-Architecture
mapping	I-Architecture
and	O
protection	O
.	O
</s>
<s>
It	O
was	O
the	O
first	O
model	O
to	O
support	O
an	O
optional	O
FP11	O
floating-point	B-Algorithm
coprocessor	B-General_Concept
,	O
which	O
established	O
the	O
format	O
used	O
in	O
later	O
models	O
.	O
</s>
<s>
PDP-11/35	O
and	O
PDP-11/40	B-Device
–	O
1973	O
.	O
</s>
<s>
Microprogrammed	O
successors	O
to	O
the	O
PDP-11/20	O
;	O
the	O
design	O
team	O
was	O
led	O
by	O
Jim	O
O'Loughlin	O
.	O
</s>
<s>
PDP-11/05	O
and	O
PDP-11/10	O
–	O
1972	O
.	O
</s>
<s>
A	O
cost-reduced	O
successor	O
to	O
the	O
PDP-11/20	O
.	O
</s>
<s>
DEC	O
Datasystem	O
350	O
models	O
from	O
1975	O
include	O
the	O
PDP-11/10	O
.	O
</s>
<s>
PDP-11/70	B-Device
–	O
1975	O
.	O
</s>
<s>
The	O
11/45	O
architecture	O
expanded	O
to	O
allow	O
4MB	O
of	O
physical	O
memory	O
segregated	O
onto	O
a	O
private	O
memory	O
bus	B-General_Concept
,	O
2KB	O
of	O
cache	B-General_Concept
memory	I-General_Concept
,	O
and	O
much	O
faster	O
I/O	B-General_Concept
devices	I-General_Concept
connected	O
via	O
the	O
Massbus	B-Architecture
.	O
</s>
<s>
PDP-11/34	O
(	O
1976	O
)	O
and	O
PDP-11/04	O
(	O
1975	O
)	O
–	O
Cost-reduced	O
follow-on	O
products	O
to	O
the	O
11/35	O
and	O
11/05	O
;	O
the	O
PDP-11/34	O
concept	O
was	O
created	O
by	O
Bob	O
Armstrong	O
.	O
</s>
<s>
The	O
11/34	O
supports	O
up	O
to	O
256kB	O
of	O
Unibus	B-Device
memory	O
.	O
</s>
<s>
The	O
PDP-11/34a	O
(	O
1978	O
)	O
supports	O
a	O
fast	O
floating-point	B-Algorithm
option	O
,	O
and	O
the	O
11/34c	O
(	O
same	O
year	O
)	O
supported	O
a	O
cache	B-General_Concept
memory	I-General_Concept
option	O
.	O
</s>
<s>
PDP-11/60	O
–	O
1977	O
.	O
</s>
<s>
A	O
PDP-11	B-Device
with	O
user-writable	O
microcontrol	O
store	O
;	O
this	O
was	O
designed	O
by	O
another	O
team	O
led	O
by	O
Jim	O
O'Loughlin	O
.	O
</s>
<s>
PDP-11/44	B-Device
–	O
1979	O
.	O
</s>
<s>
A	O
replacement	O
for	O
the	O
11/45	O
and	O
11/70	O
,	O
introduced	O
in	O
1980	O
,	O
that	O
supports	O
optional	O
(	O
though	O
apparently	O
always	O
included	O
)	O
cache	B-General_Concept
memory	I-General_Concept
,	O
optional	O
FP-11	O
floating-point	B-General_Concept
processor	I-General_Concept
(	O
one	O
circuit	O
board	O
,	O
using	O
sixteen	O
AMD	B-General_Concept
Am2901	I-General_Concept
bit	O
slice	O
processors	O
)	O
,	O
and	O
optional	O
commercial	O
instruction	B-General_Concept
set	I-General_Concept
(	O
CIS	O
,	O
two	O
boards	O
)	O
.	O
</s>
<s>
This	O
was	O
the	O
last	O
PDP-11	B-Device
processor	O
to	O
be	O
constructed	O
using	O
discrete	O
logic	O
gates	O
;	O
later	O
models	O
were	O
all	O
microprocessor-based	O
.	O
</s>
<s>
It	O
was	O
also	O
the	O
last	O
PDP-11	B-Device
system	O
architecture	O
created	O
by	O
Digital	O
Equipment	O
Corporation	O
,	O
later	O
models	O
were	O
VLSI	O
chip	O
realizations	O
of	O
the	O
existing	O
system	O
architectures	O
.	O
</s>
<s>
PDP-11/24	O
–	O
1979	O
.	O
</s>
<s>
First	O
VLSI	O
PDP-11	B-Device
for	O
Unibus	B-Device
,	O
using	O
the	O
"	O
Fonz-11	O
"	O
(	O
F11	O
)	O
chip	O
set	O
with	O
a	O
Unibus	B-Device
adapter	O
.	O
</s>
<s>
PDP-11/84	O
–	O
1985-1986	O
.	O
</s>
<s>
Using	O
the	O
VLSI	O
"	B-Device
Jaws-11	I-Device
"	I-Device
(	O
J11	O
)	O
chip	O
set	O
with	O
a	O
Unibus	B-Device
adapter	O
.	O
</s>
<s>
PDP-11/94	O
–	O
1990	O
.	O
</s>
<s>
The	O
following	O
models	O
use	O
the	O
Q-Bus	B-Architecture
as	O
their	O
principal	O
bus	B-General_Concept
:	O
</s>
<s>
PDP-11/03	O
(	O
also	O
known	O
as	O
the	O
LSI-11/03	O
)	O
–	O
The	O
first	O
PDP-11	B-Device
implemented	O
with	O
large-scale	O
integration	O
ICs	O
,	O
this	O
system	O
uses	O
a	O
four-package	O
MCP-1600	B-General_Concept
chipset	O
from	O
Western	O
Digital	O
and	O
supports	O
60KB	O
of	O
memory	O
.	O
</s>
<s>
PDP-11/23	O
+	O
/MicroPDP-11/23	O
–	O
Improved	O
11/23	O
with	O
more	O
functions	O
on	O
the	O
(	O
larger	O
)	O
processor	O
card	O
.	O
</s>
<s>
MicroPDP-11/73	B-Device
–	O
The	O
third	O
generation	O
LSI-11	O
,	O
this	O
system	O
uses	O
the	O
faster	O
"	B-Device
Jaws-11	I-Device
"	I-Device
(	O
J-11	B-Device
)	O
chip	O
set	O
and	O
supports	O
up	O
to	O
4MB	O
of	O
memory	O
.	O
</s>
<s>
MicroPDP-11/83	O
–	O
Faster	O
11/73	O
with	O
PMI	O
(	O
private	O
memory	O
interconnect	B-General_Concept
)	O
.	O
</s>
<s>
MicroPDP-11/93	O
–	O
Faster	O
11/83	O
;	O
final	O
DEC	O
Q-Bus	B-Architecture
PDP-11	B-Device
model	O
.	O
</s>
<s>
KXJ11	O
–	O
Q-Bus	B-Architecture
card	O
(	O
M7616	O
)	O
with	O
PDP-11	B-Device
based	O
peripheral	O
processor	O
and	O
DMA	B-General_Concept
controller	I-General_Concept
.	O
</s>
<s>
Based	O
on	O
a	O
J11	O
CPU	B-General_Concept
equipped	O
with	O
512KB	O
of	O
RAM	O
,	O
64KB	O
of	O
ROM	O
,	O
and	O
parallel	O
and	O
serial	B-Protocol
interfaces	I-Protocol
.	O
</s>
<s>
Mentec	O
M100	O
–	O
Mentec	O
redesign	O
of	O
the	O
11/93	O
,	O
with	O
J-11	B-Device
chipset	O
at	O
19.66MHz	O
,	O
four	O
on-board	O
serial	B-Protocol
ports	I-Protocol
,	O
1-4MB	O
of	O
on-board	O
memory	O
,	O
and	O
optional	O
FPU	B-General_Concept
.	O
</s>
<s>
Mentec	O
M11	O
–	O
Processor	O
upgrade	O
board	O
;	O
microcode	B-Device
implementation	O
of	O
PDP-11	B-Device
instruction	B-General_Concept
set	I-General_Concept
by	O
Mentec	O
,	O
using	O
the	O
TI	O
8832	O
ALU	O
and	O
TI	O
8818	O
microsequencer	O
from	O
Texas	O
Instruments	O
.	O
</s>
<s>
Mentec	O
M1	O
–	O
Processor	O
upgrade	O
board	O
;	O
microcode	B-Device
implementation	O
of	O
PDP-11	B-Device
instruction	B-General_Concept
set	I-General_Concept
by	O
Mentec	O
,	O
using	O
Atmel	O
0.35μm	O
ASIC	O
.	O
</s>
<s>
Quickware	O
QED-993	O
–	O
High	O
performance	O
PDP-11/93	O
processor	O
upgrade	O
board	O
.	O
</s>
<s>
The	O
PDT	O
series	O
were	O
desktop	B-General_Concept
systems	I-General_Concept
marketed	O
as	O
"	O
smart	O
terminals	O
"	O
.	O
</s>
<s>
The	O
/110	O
and	O
/130	O
were	O
housed	O
in	O
a	O
VT100	B-Device
terminal	B-General_Concept
enclosure	O
.	O
</s>
<s>
The	O
/150	O
was	O
housed	O
in	O
a	O
table-top	O
unit	O
which	O
included	O
two	O
8-inch	B-Device
floppy	I-Device
drives	O
,	O
three	O
asynchronous	O
serial	B-Protocol
ports	I-Protocol
,	O
one	O
printer	O
port	O
,	O
one	O
modem	O
port	O
and	O
one	O
synchronous	O
serial	B-Protocol
port	I-Protocol
and	O
required	O
an	O
external	O
terminal	B-General_Concept
.	O
</s>
<s>
The	O
/150	O
in	O
combination	O
with	O
a	O
VT105	O
terminal	B-General_Concept
was	O
also	O
sold	O
as	O
MiniMINC	O
,	O
a	O
budget	O
version	O
of	O
the	O
MINC-11	O
.	O
</s>
<s>
The	O
DEC	B-Device
Professional	I-Device
series	I-Device
are	O
desktop	O
PCs	O
intended	O
to	O
compete	O
with	O
IBM	O
's	O
earlier	O
8088	B-Device
and	O
80286	B-General_Concept
based	O
personal	O
computers	O
.	O
</s>
<s>
The	O
models	O
are	O
equipped	O
with	O
5	O
inch	O
floppy	B-Device
disk	I-Device
drives	I-Device
and	O
hard	B-Device
disks	I-Device
,	O
except	O
the	O
325	O
which	O
has	O
no	O
hard	B-Device
disk	I-Device
.	O
</s>
<s>
The	O
original	O
operating	B-General_Concept
system	I-General_Concept
was	O
P/OS	B-Application
,	O
which	O
was	O
essentially	O
RSX-11M	B-Application
+	O
with	O
a	O
menu	O
system	O
on	O
top	O
.	O
</s>
<s>
As	O
the	O
design	O
was	O
intended	O
to	O
avoid	O
software	O
exchange	O
with	O
existing	O
PDP-11	B-Device
models	O
,	O
the	O
poor	O
market	O
response	O
was	O
unsurprising	O
.	O
</s>
<s>
The	O
RT-11	B-Operating_System
operating	B-General_Concept
system	I-General_Concept
was	O
eventually	O
ported	O
to	O
the	O
PRO	O
series	O
.	O
</s>
<s>
A	O
port	O
of	O
the	O
RSTS/E	B-Operating_System
operating	B-General_Concept
system	I-General_Concept
to	O
the	O
PRO	O
series	O
was	O
also	O
done	O
internal	O
to	O
DEC	O
,	O
but	O
it	O
was	O
not	O
released	O
.	O
</s>
<s>
The	O
PRO-325	B-Device
and	O
-350	O
units	O
are	O
based	O
on	O
the	O
DCF-11	O
(	O
"	O
Fonz	O
"	O
)	O
chipset	O
,	O
the	O
same	O
as	O
found	O
in	O
the	O
11/23	O
,	O
11/23	O
+	O
and	O
11/24	O
.	O
</s>
<s>
The	O
PRO-380	B-Device
is	O
based	O
on	O
the	O
DCJ-11	O
(	O
"	O
Jaws	O
"	O
)	O
chipset	O
,	O
the	O
same	O
as	O
found	O
in	O
the	O
11/53	O
,	O
73	O
,	O
83	O
and	O
others	O
,	O
though	O
running	O
only	O
at	O
10MHz	O
because	O
of	O
limitations	O
in	O
the	O
support	O
chipset	O
.	O
</s>
<s>
PDP-11/27	O
–	O
A	O
Jaws-11	O
implementation	O
that	O
would	O
have	O
used	O
the	O
VAXBI	B-Architecture
Bus	I-Architecture
as	O
its	O
principal	O
I/O	B-General_Concept
bus	I-General_Concept
.	O
</s>
<s>
PDP-11/68	O
–	O
A	O
follow-on	O
to	O
the	O
PDP-11/60	O
that	O
would	O
have	O
supported	O
4MB	O
of	O
physical	O
memory	O
.	O
</s>
<s>
PDP-11/74	O
–	O
A	O
PDP-11/70	B-Device
that	O
was	O
extended	O
to	O
contain	O
multiprocessing	O
features	O
.	O
</s>
<s>
Another	O
variation	O
on	O
the	O
11/74	O
contained	O
both	O
the	O
multiprocessing	O
features	O
and	O
the	O
Commercial	O
Instruction	B-General_Concept
Set	I-General_Concept
.	O
</s>
<s>
A	O
four	O
processor	O
system	O
was	O
maintained	O
by	O
the	O
RSX-11	B-Application
operating	B-General_Concept
system	I-General_Concept
development	O
team	O
for	O
testing	O
and	O
a	O
uniprocessor	B-Operating_System
system	I-Operating_System
served	O
PDP-11	B-Device
engineering	O
for	O
general	O
purpose	O
timesharing	B-General_Concept
.	O
</s>
<s>
The	O
11/74	O
was	O
due	O
to	O
be	O
introduced	O
around	O
the	O
same	O
time	O
as	O
the	O
announcement	O
of	O
the	O
new	O
32-bit	O
product	O
line	O
and	O
the	O
first	O
model	O
:	O
the	O
VAX	B-Device
11/780	O
.	O
</s>
<s>
In	O
any	O
case	O
,	O
DEC	O
never	O
entirely	O
migrated	O
its	O
PDP-11	B-Device
customer	O
base	O
to	O
the	O
VAX	B-Device
.	O
</s>
<s>
The	O
primary	O
reason	O
was	O
not	O
performance	O
,	O
but	O
the	O
PDP-11	B-Device
'	O
s	O
superior	O
real-time	B-General_Concept
responsiveness	O
.	O
</s>
<s>
GT40	B-Device
–	O
VT11	O
vector	O
graphics	O
terminal	B-General_Concept
using	O
a	O
PDP-11/10	O
.	O
</s>
<s>
GT42	O
–	O
VT11	O
vector	O
graphics	O
terminal	B-General_Concept
using	O
a	O
PDP-11/10	O
.	O
</s>
<s>
GT44	O
–	O
VT11	O
vector	O
graphics	O
terminal	B-General_Concept
using	O
a	O
PDP-11/40	B-Device
.	O
</s>
<s>
GT62	O
–	O
VS60	O
vector	O
graphics	O
workstation	B-Device
using	O
a	O
PDP-11/34a	O
and	O
VT48	O
graphics	O
processor	O
.	O
</s>
<s>
H11	B-Device
–	O
Heathkit	O
OEM	O
version	O
of	O
the	O
LSI-11/03	O
.	O
</s>
<s>
VT20	O
–	O
Terminal	B-General_Concept
with	O
PDP-11/05	O
with	O
direct	O
mapped	O
character	O
display	O
for	O
text	O
editing	O
and	O
typesetting	O
(	O
predecessor	O
of	O
the	O
VT71	O
)	O
.	O
</s>
<s>
VT71	O
–	O
Terminal	B-General_Concept
with	O
LSI-11/03	O
and	O
Q-Bus	B-Architecture
backplane	B-Architecture
with	O
direct	O
mapped	O
character	O
display	O
for	O
text	O
editing	O
and	O
typesetting	O
.	O
</s>
<s>
VT103	B-Device
–	O
VT100	B-Device
with	O
backplane	B-Architecture
to	O
host	O
an	O
LSI-11	O
.	O
</s>
<s>
VT173	O
–	O
A	O
high-end	O
editing	O
terminal	B-General_Concept
containing	O
an	O
11/03	O
,	O
which	O
loaded	O
its	O
editing	O
software	O
over	O
a	O
serial	O
connection	O
to	O
a	O
host	O
minicomputer	B-Architecture
.	O
</s>
<s>
Used	O
in	O
various	O
publishing	O
environments	O
,	O
it	O
was	O
also	O
offered	O
with	O
DECset	O
,	O
Digital	O
's	O
VAX/VMS	O
3.x	O
native	O
mode	O
OEM	O
version	O
of	O
the	O
Datalogics	O
Pager	O
automated	O
batch	O
composition	O
engine	O
.	O
</s>
<s>
Early	O
versions	O
of	O
the	O
MINC-specific	O
software	O
package	O
would	O
not	O
run	O
on	O
the	O
11/23	O
processor	O
because	O
of	O
subtle	O
changes	O
in	O
the	O
instruction	B-General_Concept
set	I-General_Concept
;	O
MINC	O
1.2	O
is	O
documented	O
as	O
compatible	O
with	O
the	O
later	O
processor	O
.	O
</s>
<s>
C.mmp	B-Operating_System
–	O
Multiprocessor	O
system	O
from	O
Carnegie	O
Mellon	O
University	O
.	O
</s>
<s>
The	O
Unimation	O
robot	O
arm	O
controllers	O
used	O
Q-Bus	B-Architecture
LSI-11/73	O
systems	O
with	O
a	O
DEC	O
M8192	O
/	O
KDJ11-A	O
processor	O
board	O
and	O
two	O
DEC	O
DLV11-J	O
(	O
M8043	O
)	O
async	O
serial	B-Protocol
interface	I-Protocol
boards	O
.	O
</s>
<s>
SBC	O
11/21	O
(	O
boardname	O
KXT11	O
)	O
Falcon	O
and	O
Falcon	O
Plus	O
–	O
single	O
board	O
computer	O
on	O
a	O
Q-Bus	B-Architecture
card	O
implementing	O
the	O
basic	O
PDP-11	B-Device
instruction	B-General_Concept
set	I-General_Concept
,	O
based	O
on	O
T11	O
chipset	O
containing	O
32KB	O
static	O
RAM	O
,	O
two	O
ROM	O
sockets	O
,	O
three	O
serial	B-Protocol
lines	I-Protocol
,	O
20bit	O
parallel	O
I/O	B-General_Concept
,	O
three	O
interval	O
timers	O
and	O
a	O
two-channel	O
DMA	B-General_Concept
controller	I-General_Concept
.	O
</s>
<s>
Up	O
to	O
14Falcons	O
could	O
be	O
placed	O
into	O
one	O
Q-Bus	B-Architecture
system	O
.	O
</s>
<s>
KXJ11	O
Q-Bus	B-Architecture
card	O
(	O
M7616	O
)	O
with	O
PDP-11	B-Device
based	O
peripheral	O
processor	O
and	O
DMA	B-General_Concept
controller	I-General_Concept
.	O
</s>
<s>
Based	O
on	O
a	O
J11	O
CPU	B-General_Concept
equipped	O
with	O
512KB	O
RAM	O
,	O
64KB	O
ROM	O
and	O
parallel	O
and	O
serial	B-Protocol
interfaces	I-Protocol
.	O
</s>
<s>
HSC	O
high	O
end	O
CI	O
disk	O
controllers	O
used	O
backplane	B-Architecture
mounted	O
J11	O
and	O
F11	O
processor	O
cards	O
to	O
run	O
the	O
CHRONIC	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
VAX	B-Device
Console	O
–	O
The	O
DEC	B-Device
Professional	I-Device
Series	I-Device
PC-38N	O
with	O
a	O
real-time	B-General_Concept
interface	O
(	O
RTI	O
)	O
was	O
used	O
as	O
the	O
console	O
for	O
the	O
VAX	B-Device
8500	I-Device
and	I-Device
8550	I-Device
.	O
</s>
<s>
The	O
RTI	O
has	O
two	O
serial	B-Protocol
line	I-Protocol
units	O
:	O
one	O
connects	O
to	O
the	O
VAX	B-Device
environmental	O
monitoring	O
module	O
(	O
EMM	O
)	O
and	O
the	O
other	O
is	O
a	O
spare	O
that	O
could	O
be	O
used	O
for	O
data	O
transfer	O
.	O
</s>
<s>
The	O
RTI	O
also	O
has	O
a	O
programmable	O
peripheral	O
interface	O
(	O
PPI	O
)	O
consisting	O
of	O
three	O
8-bit	O
ports	O
for	O
transferring	O
data	O
,	O
address	O
,	O
and	O
control	O
signals	O
between	O
console	O
and	O
the	O
VAX	B-Device
console	O
interface	O
.	O
</s>
<s>
The	O
PDP-11	B-Device
was	O
sufficiently	O
popular	O
that	O
many	O
unlicensed	O
PDP-11-compatible	O
minicomputers	B-Architecture
and	O
microcomputers	O
were	O
produced	O
in	O
Eastern	O
Bloc	O
countries	O
.	O
</s>
<s>
Some	O
were	O
pin-compatible	O
with	O
the	O
PDP-11	B-Device
and	O
could	O
use	O
its	O
peripherals	O
and	O
system	O
software	O
.	O
</s>
<s>
SM-4	B-Device
,	O
SM-1420	B-Device
,	O
SM-1600	O
,	O
Electronika	O
100-25	O
,	O
Electronika	B-Device
BK	I-Device
series	O
,	O
Electronika	B-Device
60	I-Device
,	O
Electronika	O
85	O
,	O
DVK	B-Device
,	O
UKNC	B-Device
,	O
and	O
some	O
models	O
of	O
the	O
SM	B-Device
EVM	I-Device
series	O
(	O
in	O
the	O
Soviet	O
Union	O
)	O
.	O
</s>
<s>
SM-4	B-Device
,	O
SM-1420	B-Device
,	O
IZOT-1016	O
and	O
peripherals	O
(	O
in	O
Bulgaria	O
)	O
.	O
</s>
<s>
SM-1620	O
,	O
SM-1630	O
(	O
in	O
East	O
Germany	O
)	O
.	O
</s>
<s>
SM-4	B-Device
,	O
TPA-1140	O
,	O
TPA-1148	O
,	O
TPA-11/440	O
(	O
in	O
Hungary	O
)	O
.	O
</s>
<s>
SM-4/20	O
,	O
SM	B-Device
52-11	O
,	O
JPR-12R	O
(	O
in	O
Czechoslovakia	O
)	O
.	O
</s>
<s>
The	O
CalData	O
hardware	O
was	O
sufficiently	O
DEC-compatible	O
that	O
CalData	O
memory	O
boards	O
could	O
be	O
used	O
in	O
DEC	B-Device
PDP-11	I-Device
systems	O
.	O
</s>
<s>
CORAL	O
series	O
(	O
made	O
at	O
ICE	O
Felix	O
in	O
Bucharest	O
)	O
and	O
the	O
INDEPENDENT	O
series	O
(	O
made	O
at	O
ITC	O
Timișoara	O
)	O
running	O
the	O
RSX-11M	B-Application
operating	B-General_Concept
system	I-General_Concept
(	O
in	O
Romania	O
)	O
.	O
</s>
<s>
The	O
CORAL	O
series	O
had	O
several	O
models	O
:	O
the	O
CORAL	O
4001	O
was	O
roughly	O
equivalent	O
to	O
the	O
PDP-11/04	O
,	O
the	O
CORAL	O
4011	O
was	O
a	O
PDP	O
11/34	O
clone	O
,	O
while	O
the	O
CORAL	O
4030	O
was	O
a	O
PDP-11/44	B-Device
clone	O
.	O
</s>
<s>
These	O
were	O
used	O
in	O
state-owned	O
companies	O
and	O
in	O
public	O
universities	O
,	O
originally	O
operated	O
with	O
punched	B-Architecture
cards	I-Architecture
,	O
later	O
through	O
video	B-General_Concept
terminals	I-General_Concept
like	O
the	O
Romanian	O
DAF-2020	O
,	O
to	O
teach	O
FORTRAN	O
and	O
Pascal	O
,	O
until	O
replaced	O
by	O
IBM	B-Device
PC	I-Device
compatibles	O
,	O
starting	O
in	O
1991	O
.	O
</s>
<s>
Several	O
operating	B-General_Concept
systems	I-General_Concept
were	O
available	O
for	O
the	O
PDP-11	B-Device
.	O
</s>
<s>
The	O
DECSA	O
communications	O
server	O
was	O
a	O
communications	O
platform	O
developed	O
by	O
DEC	O
based	O
on	O
a	O
PDP-11/24	O
,	O
with	O
the	O
provision	O
for	O
user	O
installable	O
I/O	B-General_Concept
cards	O
including	O
asynchronous	O
and	O
synchronous	O
modules	O
.	O
</s>
<s>
This	O
product	O
was	O
used	O
as	O
one	O
of	O
the	O
earliest	O
commercial	O
platforms	O
upon	O
which	O
networking	O
products	O
could	O
be	O
built	O
,	O
including	O
X.25	B-Protocol
gateways	O
,	O
SNA	B-Architecture
gateways	O
,	O
routers	B-Protocol
,	O
and	O
terminal	B-Device
servers	I-Device
.	O
</s>
<s>
Ethernet	O
adaptors	O
,	O
such	O
as	O
the	O
DEQNA	O
Q-Bus	B-Architecture
card	O
,	O
were	O
also	O
available	O
.	O
</s>
<s>
A	O
wide	O
range	O
of	O
peripherals	O
were	O
available	O
;	O
some	O
of	O
them	O
were	O
also	O
used	O
in	O
other	O
DEC	O
systems	O
like	O
the	O
PDP-8	B-Device
or	O
PDP-10	B-Device
.	O
</s>
<s>
The	O
following	O
are	O
some	O
of	O
the	O
more	O
common	O
PDP-11	B-Device
peripherals	O
.	O
</s>
<s>
The	O
PDP-11	B-Device
family	O
of	O
computers	O
was	O
used	O
for	O
many	O
purposes	O
.	O
</s>
<s>
It	O
was	O
used	O
as	O
a	O
standard	O
minicomputer	B-Architecture
for	O
general-purpose	O
computing	O
,	O
such	O
as	O
timesharing	B-General_Concept
,	O
scientific	O
,	O
educational	O
,	O
medical	O
,	O
government	O
or	O
business	O
computing	O
.	O
</s>
<s>
Another	O
common	O
application	O
was	O
real-time	B-General_Concept
process	O
control	O
and	O
factory	O
automation	O
.	O
</s>
<s>
Some	O
OEM	O
models	O
were	O
also	O
frequently	O
used	O
as	O
embedded	B-Architecture
systems	I-Architecture
to	O
control	O
complex	O
systems	O
like	O
traffic-light	O
systems	O
,	O
medical	O
systems	O
,	O
numerical	O
controlled	O
machining	O
,	O
or	O
for	O
network-management	O
.	O
</s>
<s>
An	O
example	O
of	O
such	O
use	O
of	O
PDP-11s	B-Device
was	O
the	O
management	O
of	O
the	O
packet	O
switched	O
network	O
Datanet	O
1	O
.	O
</s>
<s>
In	O
the	O
1980s	O
,	O
the	O
UK	O
's	O
air	B-Application
traffic	I-Application
control	I-Application
radar	O
processing	O
was	O
conducted	O
on	O
a	O
PDP	O
11/34	O
system	O
known	O
as	O
PRDS	O
–	O
Processed	O
Radar	O
Display	O
System	O
at	O
RAF	O
West	O
Drayton	O
.	O
</s>
<s>
In	O
2013	O
,	O
it	O
was	O
reported	O
that	O
PDP-11	B-Device
programmers	O
would	O
be	O
needed	O
to	O
control	O
nuclear	O
power	O
plants	O
through	O
2050	O
.	O
</s>
<s>
As	O
such	O
,	O
they	O
were	O
in	O
use	O
until	O
their	O
software	O
was	O
rendered	O
inoperable	O
by	O
the	O
Year	B-Error_Name
2000	I-Error_Name
problem	I-Error_Name
.	O
</s>
<s>
The	O
US	O
Navy	O
used	O
a	O
PDP-11/34	O
to	O
control	O
its	O
Multi-station	O
Spatial	O
Disorientation	O
Device	O
,	O
a	O
simulator	O
used	O
in	O
pilot	O
training	O
,	O
until	O
2007	O
,	O
when	O
it	O
was	O
replaced	O
by	O
a	O
PC-based	O
emulator	O
that	O
could	O
run	O
the	O
original	O
PDP-11	B-Device
software	O
and	O
interface	O
with	O
custom	O
Unibus	B-Device
controller	O
cards	O
.	O
</s>
<s>
A	O
PDP-11/45	B-Device
was	O
used	O
for	O
the	O
experiment	O
that	O
discovered	O
the	O
J/ψ	O
meson	O
at	O
the	O
Brookhaven	O
National	O
Laboratory	O
.	O
</s>
<s>
In	O
1976	O
,	O
Samuel	O
C	B-Language
.	O
C	B-Language
.	O
Ting	O
received	O
the	O
Nobel	O
Prize	O
for	O
this	O
discovery	O
.	O
</s>
<s>
Another	O
PDP-11/45	B-Device
was	O
used	O
to	O
create	O
the	O
Death	O
Star	O
plans	O
during	O
the	O
briefing	O
sequence	O
in	O
Star	B-Application
Wars	I-Application
.	O
</s>
<s>
Ersatz-11	O
,	O
a	O
product	O
of	O
D	O
Bit	O
,	O
emulates	O
the	O
PDP-11	B-Device
instruction	B-General_Concept
set	I-General_Concept
running	O
under	O
DOS	O
,	O
OS/2	O
,	O
Windows	O
,	O
Linux	B-Application
or	O
bare	O
metal	O
(	O
no	O
OS	O
)	O
.	O
</s>
<s>
It	O
can	O
be	O
used	O
to	O
run	O
RSTS	B-Operating_System
or	O
other	O
PDP-11	B-Device
operating	B-General_Concept
systems	I-General_Concept
.	O
</s>
<s>
SimH	B-Application
is	O
an	O
emulator	O
that	O
compiles	O
and	O
runs	O
on	O
a	O
number	O
of	O
platforms	O
(	O
including	O
Linux	B-Application
)	O
and	O
supports	O
hardware	O
emulation	O
for	O
the	O
DEC	O
PDP-1	O
,	O
PDP-8	B-Device
,	O
PDP-10	B-Device
,	O
PDP-11	B-Device
,	O
VAX	B-Device
,	O
AltairZ80	O
,	O
several	O
IBM	O
mainframes	O
,	O
and	O
other	O
minicomputers	B-Architecture
.	O
</s>
<s>
and	O
are	O
embedded	O
real-time	B-General_Concept
device	O
emulators	O
to	O
run	O
in	O
UNIBUS	B-Device
resp	O
.	O
</s>
<s>
QBUS	B-Architecture
slots	O
.	O
</s>
<s>
Implemented	O
devices	O
include	O
currently	O
a	O
CPU	B-General_Concept
,	O
memory	O
,	O
several	O
disk	B-Device
subsystems	I-Device
,	O
serial	O
DL11	B-Device
and	O
M9312	O
boot	B-Operating_System
ROM	O
.	O
</s>
<s>
Disk	O
images	O
are	O
SimH	B-Application
compatible	O
.	O
</s>
<s>
UniBone	O
is	O
used	O
on	O
hardware	O
ranging	O
from	O
PDP-11/20	O
to	O
11/84	O
and	O
VAX11/750	O
,	O
QBone	O
from	O
LSI11/03	O
to	O
MicroVAXes	B-Device
.	O
</s>
<s>
Core	O
is	O
a	O
BeagleBone	O
Black	O
running	O
Debian	O
Linux	B-Application
.	O
</s>
<s>
Independent	O
real	O
time	O
processors	O
eliminate	O
the	O
need	O
for	O
a	O
FPGA	O
,	O
the	O
whole	O
project	O
is	O
written	O
in	O
Open	O
Source	O
C/C	O
++	O
.	O
</s>
