<s>
Programmed	B-Device
Data	I-Device
Processor	I-Device
(	O
PDP	O
)	O
,	O
referred	O
to	O
by	O
some	O
customers	O
,	O
media	O
and	O
authors	O
as	O
"	O
Programmable	B-Device
Data	I-Device
Processor	I-Device
,	O
"	O
is	O
a	O
term	O
used	O
by	O
the	O
Digital	O
Equipment	O
Corporation	O
from	O
1957	O
to	O
1990	O
for	O
several	O
lines	O
of	O
minicomputers	B-Architecture
.	O
</s>
<s>
The	O
venture	O
capitalists	O
behind	O
Digital	O
(	O
especially	O
Georges	O
Doriot	O
)	O
would	O
not	O
support	O
Digital	O
's	O
attempting	O
to	O
build	O
a	O
'	O
computer	O
 '	O
and	O
the	O
term	O
'	O
minicomputer	B-Architecture
 '	O
had	O
not	O
yet	O
been	O
coined	O
.	O
</s>
<s>
So	O
instead	O
,	O
Digital	O
used	O
their	O
existing	O
line	O
of	O
logic	O
modules	O
to	O
build	O
a	O
Programmed	B-Device
Data	I-Device
Processor	I-Device
and	O
aimed	O
it	O
at	O
a	O
market	O
that	O
could	O
not	O
afford	O
the	O
larger	O
computers	O
.	O
</s>
<s>
PDP-1	B-Device
The	O
original	O
PDP	O
,	O
an	O
18-bit	B-General_Concept
4-rack	O
machine	O
used	O
in	O
early	O
time-sharing	B-General_Concept
operating	I-General_Concept
system	I-General_Concept
work	O
,	O
and	O
prominent	O
in	O
MIT	O
's	O
early	O
hacker	O
culture	O
,	O
which	O
led	O
to	O
the	O
(	O
Massachusetts	O
)	O
Route	O
128	O
hardware	O
startup	O
belt	O
(	O
DEC	O
's	O
second	O
home	O
,	O
Prime	O
Computer	O
,	O
etc	O
.	O
)	O
.	O
</s>
<s>
What	O
is	O
believed	O
to	O
be	O
the	O
first	O
video	O
game	O
,	O
Spacewar	O
!,	O
was	O
developed	O
for	O
this	O
machine	O
,	O
along	O
with	O
the	O
first	O
known	O
word	B-General_Concept
processing	I-General_Concept
program	O
for	O
a	O
general-purpose	O
computer	O
,	O
"	O
Expensive	B-Application
Typewriter	I-Application
"	O
.	O
</s>
<s>
The	O
last	O
of	O
DEC	O
's	O
53	O
PDP-1	B-Device
computers	O
was	O
built	O
in	O
1969	O
,	O
a	O
decade	O
after	O
the	O
first	O
,	O
and	O
nearly	O
all	O
of	O
them	O
were	O
still	O
in	O
use	O
as	O
of	O
1975	O
.	O
</s>
<s>
Its	O
architectural	O
successors	O
as	O
18-bit	B-General_Concept
machines	O
were	O
the	O
PDP-4	B-Device
,	O
PDP-7	B-Device
,	O
PDP-9	B-Device
,	O
and	O
the	O
PDP-15	B-Device
.	O
</s>
<s>
PDP-2	B-Device
A	O
number	O
reserved	O
for	O
an	O
unbuilt	O
,	O
undesigned	O
24-bit	O
design	O
.	O
</s>
<s>
PDP-3	B-Device
First	O
DEC-designed	O
(	O
for	O
US	O
"	O
black	O
budget	O
"	O
outfits	O
)	O
36-bit	O
machine	O
,	O
though	O
DEC	O
did	O
not	O
offer	O
it	O
as	O
a	O
product	O
.	O
</s>
<s>
The	O
only	O
PDP-3	B-Device
was	O
built	O
by	O
the	O
CIA	O
's	O
Scientific	O
Engineering	O
Institute	O
(	O
SEI	O
)	O
in	O
Waltham	O
,	O
Massachusetts	O
to	O
process	O
radar	O
cross	O
section	O
data	O
for	O
the	O
Lockheed	O
A-12	O
reconnaissance	O
aircraft	O
in	O
1960	O
.	O
</s>
<s>
Architecturally	O
it	O
was	O
essentially	O
a	O
PDP-1	B-Device
controlling	O
a	O
PDP-1	B-Device
stretched	O
to	O
36-bit	O
word	O
width	O
.	O
</s>
<s>
PDP-4	B-Device
This	O
18-bit	B-General_Concept
machine	O
,	O
first	O
shipped	O
in	O
1962	O
of	O
which	O
"	O
approximately	O
54	O
were	O
sold	O
"	O
was	O
a	O
compromise	O
:	O
"	O
with	O
slower	O
memory	O
and	O
different	O
packaging	O
"	O
than	O
the	O
PDP-1	B-Device
,	O
but	O
priced	O
at	O
$	O
65,000	O
-	O
considerably	O
less	O
than	O
its	O
predecessor	O
(	O
about	O
half	O
the	O
price	O
)	O
.	O
</s>
<s>
All	O
later	O
18-bit	B-General_Concept
PDP	O
machines	O
(	O
7	O
,	O
9	O
and	O
15	O
)	O
are	O
based	O
on	O
a	O
similar	O
,	O
but	O
enlarged	O
instruction	B-General_Concept
set	I-General_Concept
,	O
more	O
powerful	O
,	O
but	O
based	O
on	O
the	O
same	O
concepts	O
as	O
the	O
12-bit	B-Device
PDP-5/PDP	O
-8	O
series	O
.	O
</s>
<s>
The	O
installation	O
at	O
Chalk	O
River	O
,	O
Ontario	O
included	O
an	O
early	O
PDP-4	B-Device
with	O
a	O
display	O
system	O
and	O
a	O
new	O
PDP-5	B-Device
as	O
interface	O
to	O
the	O
research	O
reactor	O
instrumentation	O
and	O
control	O
.	O
</s>
<s>
PDP-5	B-Device
It	O
was	O
the	O
world	O
's	O
first	O
commercially	O
produced	O
minicomputer	B-Architecture
and	O
DEC	O
's	O
first	O
12-bit	B-Device
machine	O
(	O
1963	O
)	O
.	O
</s>
<s>
The	O
instruction	B-General_Concept
set	I-General_Concept
was	O
later	O
expanded	O
in	O
the	O
PDP-8	B-Device
to	O
handle	O
more	O
bit	O
rotations	O
and	O
to	O
increase	O
the	O
maximum	O
memory	O
size	O
from	O
4K	O
words	O
to	O
32K	O
words	O
.	O
</s>
<s>
PDP-6	B-Device
This	O
36-bit	O
machine	O
,	O
DEC	O
's	O
first	O
large	O
PDP	O
computer	O
,	O
came	O
in	O
1964	O
with	O
the	O
first	O
DEC-supported	O
timesharing	B-General_Concept
system	O
.	O
</s>
<s>
Although	O
the	O
PDP-6	B-Device
was	O
"	O
disappointing	O
to	O
management	O
,	O
"	O
it	O
introduced	O
the	O
instruction	B-General_Concept
set	I-General_Concept
and	O
was	O
the	O
prototype	O
for	O
the	O
far	O
more	O
successful	O
PDP-10	B-Device
and	O
DEC	B-Device
System-20	I-Device
,	O
of	O
which	O
hundreds	O
were	O
sold	O
.	O
</s>
<s>
PDP-7	B-Device
Replacement	O
for	O
the	O
PDP-4	B-Device
;	O
DEC	O
's	O
first	O
wire-wrapped	O
machine	O
.	O
</s>
<s>
The	O
first	O
version	O
of	O
Unix	B-Application
,	O
and	O
the	O
first	O
version	O
of	O
B	B-Language
,	O
a	O
predecessor	O
of	O
C	B-Language
,	O
were	O
written	O
for	O
the	O
PDP-7	B-Device
at	O
Bell	O
Labs	O
,	O
as	O
was	O
the	O
first	O
version	O
(	O
by	O
DEC	O
)	O
of	O
MUMPS	B-Language
.	O
</s>
<s>
PDP-8	B-Device
12-bit	B-Device
machine	O
(	O
1965	O
)	O
with	O
a	O
tiny	O
instruction	B-General_Concept
set	I-General_Concept
;	O
DEC	O
's	O
first	O
major	O
commercial	O
success	O
and	O
the	O
start	O
of	O
the	O
minicomputer	B-Architecture
revolution	O
.	O
</s>
<s>
Over	O
50,000	O
units	O
among	O
various	O
models	O
of	O
the	O
family	O
(	O
A	O
,	O
E	O
,	O
F	O
,	O
I	O
,	O
S	O
,	O
L	O
,	O
M	B-Language
)	O
were	O
sold	O
.	O
</s>
<s>
Later	O
models	O
are	O
also	O
used	O
in	O
the	O
DECmate	B-Device
word	B-General_Concept
processor	I-General_Concept
and	O
the	O
VT-78	B-Device
workstation	B-Device
.	O
</s>
<s>
LINC-8	B-Device
A	O
hybrid	O
of	O
the	O
LINC	B-Device
and	O
PDP-8	B-Device
computers	O
;	O
two	O
instruction	B-General_Concept
sets	I-General_Concept
;	O
1966	O
.	O
</s>
<s>
Progenitor	O
of	O
the	O
PDP-12	B-Device
.	O
</s>
<s>
PDP-9	B-Device
Successor	O
to	O
the	O
PDP-7	B-Device
;	O
DEC	O
's	O
first	O
micro-programmed	O
machine	O
(	O
1966	O
)	O
.	O
</s>
<s>
It	O
features	O
a	O
speed	O
increase	O
of	O
approximately	O
twice	O
that	O
of	O
the	O
PDP-7	B-Device
.	O
</s>
<s>
The	O
PDP-9	B-Device
is	O
also	O
one	O
of	O
the	O
first	O
small	O
or	O
medium	O
scale	O
computers	O
to	O
have	O
a	O
keyboard	O
monitor	O
system	O
based	O
on	O
DIGITAL	O
's	O
own	O
small	O
magnetic	O
tape	O
units	O
(	O
DECtape	O
)	O
.	O
</s>
<s>
The	O
PDP-9	B-Device
established	O
minicomputers	B-Architecture
as	O
the	O
leading	O
edge	O
of	O
the	O
computer	O
industry	O
.	O
</s>
<s>
PDP-10	B-Device
Also	O
marketed	O
as	O
the	O
DECsystem-10	B-Device
,	O
this	O
36-bit	O
timesharing	B-General_Concept
machine	O
(	O
1966	O
)	O
was	O
quite	O
successful	O
over	O
several	O
different	O
implementations	O
(	O
KA	O
,	O
KI	O
,	O
KL	O
,	O
KS	O
)	O
and	O
models	O
.	O
</s>
<s>
The	O
instruction	B-General_Concept
set	I-General_Concept
is	O
a	O
slightly	O
elaborated	O
form	O
of	O
that	O
of	O
the	O
PDP-6	B-Device
.	O
</s>
<s>
The	O
KL	O
was	O
also	O
used	O
for	O
the	O
DECSYSTEM-20	B-Device
.	O
</s>
<s>
The	O
KS	O
was	O
used	O
for	O
the	O
2020	O
,	O
DEC	O
's	O
entry	O
in	O
the	O
distributed	B-Architecture
processing	I-Architecture
market	O
,	O
introduced	O
as	O
"	O
the	O
world	O
's	O
lowest	O
cost	O
mainframe	O
computer	O
system.	O
"	O
</s>
<s>
PDP-11	B-Device
The	O
archetypal	O
minicomputer	B-Architecture
(	O
1970	O
)	O
;	O
a	O
16-bit	B-Device
machine	O
and	O
another	O
commercial	O
success	O
for	O
DEC	O
.	O
</s>
<s>
The	O
LSI-11	O
is	O
a	O
four-chip	O
PDP-11	B-Device
used	O
primarily	O
for	O
embedded	B-Architecture
systems	I-Architecture
.	O
</s>
<s>
The	O
32-bit	O
VAX	B-Device
series	O
is	O
descended	O
from	O
the	O
PDP-11	B-Device
,	O
and	O
early	O
VAX	B-Device
models	O
have	O
a	O
PDP-11	B-Device
compatibility	O
mode	O
.	O
</s>
<s>
The	O
16-bit	B-Device
PDP-11	B-Device
instruction	B-General_Concept
set	I-General_Concept
has	O
been	O
very	O
influential	O
,	O
with	O
processors	O
ranging	O
from	O
the	O
Motorola	B-Device
68000	I-Device
to	O
the	O
Renesas	B-Device
H8	I-Device
and	O
Texas	B-Architecture
Instruments	I-Architecture
MSP430	I-Architecture
,	O
inspired	O
by	O
its	O
highly	O
orthogonal	O
,	O
general-register	O
oriented	O
instruction	B-General_Concept
set	I-General_Concept
and	O
rich	O
addressing	B-Language
modes	I-Language
.	O
</s>
<s>
The	O
PDP-11	B-Device
family	O
was	O
extremely	O
long-lived	O
,	O
spanning	O
20	O
years	O
and	O
many	O
different	O
implementations	O
and	O
technologies	O
.	O
</s>
<s>
PDP-12	B-Device
12-bit	B-Device
machine	O
(	O
1969	O
)	O
,	O
descendant	O
of	O
the	O
LINC-8	B-Device
and	O
thus	O
of	O
the	O
PDP-8	B-Device
.	O
</s>
<s>
It	O
can	O
execute	O
the	O
instruction	B-General_Concept
set	I-General_Concept
of	O
either	O
system	O
.	O
</s>
<s>
See	O
LINC	B-Device
and	O
.	O
</s>
<s>
PDP-14	B-Device
A	O
machine	O
with	O
12-bit	B-Device
instructions	O
,	O
intended	O
as	O
an	O
industrial	O
controller	O
(	O
PLC	B-Architecture
;	O
1969	O
)	O
.	O
</s>
<s>
Later	O
versions	O
(	O
for	O
example	O
,	O
the	O
PDP-14/30	O
)	O
are	O
based	O
on	O
PDP-8	B-Device
physical	O
packaging	O
technology	O
.	O
</s>
<s>
PDP-15	B-Device
DEC	O
's	O
final	O
18-bit	B-General_Concept
machine	O
(	O
1970	O
)	O
.	O
</s>
<s>
It	O
is	O
the	O
only	O
18-bit	B-General_Concept
machine	O
constructed	O
from	O
TTL	B-General_Concept
integrated	O
circuits	O
rather	O
than	O
discrete	O
transistors	O
,	O
and	O
,	O
like	O
every	O
DEC	O
18-bit	B-General_Concept
system	O
(	O
except	O
mandatory	O
on	O
the	O
PDP-1	B-Device
,	O
absent	O
on	O
the	O
PDP-4	B-Device
)	O
has	O
an	O
optional	O
integrated	O
vector	O
graphics	O
terminal	O
,	O
DEC	O
's	O
first	O
improvement	O
on	O
its	O
early-designed	O
34n	O
where	O
n	O
equalled	O
the	O
PDP	O
's	O
number	O
.	O
</s>
<s>
Later	O
versions	O
of	O
the	O
PDP-15	B-Device
run	O
a	O
real-time	O
multi-user	O
OS	O
called	O
"	O
XVM	O
"	O
.	O
</s>
<s>
The	O
final	O
model	O
,	O
the	O
PDP-15/76	O
uses	O
a	O
small	O
PDP-11	B-Device
to	O
allow	O
Unichannel	O
peripherals	O
to	O
be	O
used	O
.	O
</s>
<s>
PDP-16	B-Device
A	O
"	O
roll-your-own	O
"	O
sort	O
of	O
computer	O
using	O
Register	O
Transfer	O
Modules	O
,	O
mainly	O
intended	O
for	O
industrial	O
control	O
systems	O
with	O
more	O
capability	O
than	O
the	O
PDP-14	B-Device
.	O
</s>
<s>
The	O
PDP-16/M	O
was	O
introduced	O
in	O
1972	O
as	O
a	O
standard	O
version	O
of	O
the	O
PDP-16	B-Device
.	O
</s>
<s>
LINC	B-Device
(	O
Laboratory	B-Device
Instrument	I-Device
Computer	I-Device
)	O
,	O
originally	O
designed	O
by	O
MIT	O
's	O
Lincoln	O
Laboratory	O
,	O
some	O
built	O
by	O
DEC	O
.	O
Not	O
in	O
the	O
PDP	O
family	O
,	O
but	O
important	O
as	O
progenitor	O
of	O
the	O
PDP-12	B-Device
.	O
</s>
<s>
The	O
LINC	B-Device
and	O
the	O
PDP-8	B-Device
can	O
be	O
considered	O
the	O
first	O
minicomputers	B-Architecture
,	O
and	O
perhaps	O
the	O
first	O
personal	B-Device
computers	I-Device
as	O
well	O
.	O
</s>
<s>
The	O
PDP-8	B-Device
and	O
PDP-11	B-Device
are	O
the	O
most	O
popular	O
of	O
the	O
PDP	O
series	O
of	O
machines	O
.	O
</s>
<s>
Digital	O
never	O
made	O
a	O
PDP-20	B-Device
,	O
although	O
the	O
term	O
was	O
sometimes	O
used	O
for	O
a	O
PDP-10	B-Device
running	O
TOPS-20	B-Operating_System
(	O
officially	O
known	O
as	O
a	O
DECSYSTEM-20	B-Device
)	O
.	O
</s>
<s>
Several	O
unlicensed	O
clones	O
of	O
the	O
PDP-11	B-Device
.	O
</s>
<s>
TOAD-1	O
and	O
TOAD-2	O
,	O
Foonly	O
,	O
and	O
Systems	O
Concepts	O
PDP-10/DECSYSTEM	O
-20-compatible	O
machines	O
.	O
</s>
