<s>
The	O
PDP-1	B-Device
(	O
Programmed	O
Data	O
Processor-1	O
)	O
is	O
the	O
first	B-Architecture
computer	I-Architecture
in	O
Digital	O
Equipment	O
Corporation	O
's	O
PDP	B-Device
series	O
and	O
was	O
first	O
produced	O
in	O
1959	O
.	O
</s>
<s>
The	O
PDP-1	B-Device
is	O
the	O
original	O
hardware	O
for	O
playing	O
history	O
's	O
first	O
game	O
on	O
a	O
minicomputer	B-Architecture
,	O
Steve	O
Russell	O
's	O
Spacewar	B-Application
!	I-Application
</s>
<s>
The	O
PDP-1	B-Device
uses	O
an	O
18-bit	B-General_Concept
word	O
size	O
and	O
has	O
4096	O
words	O
as	O
standard	O
main	O
memory	O
(	O
equivalent	O
to	O
9,216	O
eight-bit	O
bytes	B-Application
,	O
though	O
the	O
system	O
actually	O
divides	O
an	O
18-bit	B-General_Concept
word	O
into	O
six-bit	O
characters	O
)	O
,	O
upgradable	O
to	O
65,536	O
words	O
.	O
</s>
<s>
The	O
PDP-1	B-Device
has	O
computing	O
power	O
roughly	O
equivalent	O
to	O
a	O
1996	O
pocket	O
organizer	O
and	O
a	O
little	O
less	O
memory	O
.	O
</s>
<s>
The	O
PDP-1	B-Device
uses	O
2,700	O
transistors	O
and	O
3,000	O
diodes	O
.	O
</s>
<s>
It	O
is	O
built	O
mostly	O
of	O
DEC	O
1000-series	O
System	B-Device
Building	I-Device
Blocks	I-Device
,	O
using	O
micro-alloy	O
and	O
micro-alloy	O
diffused	O
transistors	O
with	O
a	O
rated	O
switching	O
speed	O
of	O
5MHz	O
.	O
</s>
<s>
The	O
System	B-Device
Building	I-Device
Blocks	I-Device
are	O
packaged	O
into	O
several	O
19-inch	B-Application
racks	I-Application
.	O
</s>
<s>
Above	O
the	O
control	O
panel	O
is	O
the	O
system	O
's	O
standard	O
input/output	B-General_Concept
solution	O
,	O
a	O
punched	O
tape	O
reader	O
and	O
writer	O
.	O
</s>
<s>
The	O
PDP-1	B-Device
weighed	O
about	O
.	O
</s>
<s>
The	O
design	O
of	O
the	O
PDP-1	B-Device
is	O
based	O
on	O
the	O
pioneering	O
TX-0	B-Device
and	O
TX-2	B-Device
computers	O
,	O
designed	O
and	O
built	O
at	O
MIT	O
Lincoln	O
Laboratory	O
.	O
</s>
<s>
After	O
showing	O
a	O
prototype	O
at	O
the	O
Eastern	O
Joint	O
Computer	O
Conference	O
in	O
December	O
1959	O
,	O
DEC	O
delivered	O
the	O
first	O
PDP-1	B-Device
to	O
Bolt	O
,	O
Beranek	O
and	O
Newman	O
(	O
BBN	O
)	O
in	O
November	O
1960	O
,	O
and	O
it	O
was	O
formally	O
accepted	O
in	O
early	O
1961	O
.	O
</s>
<s>
In	O
September	O
1961	O
,	O
DEC	O
donated	O
the	O
PDP-1	B-Device
to	O
MIT	O
,	O
where	O
it	O
was	O
placed	O
in	O
the	O
room	O
next	O
to	O
its	O
ancestor	O
,	O
the	O
TX-0	B-Device
computer	O
,	O
which	O
was	O
by	O
then	O
on	O
indefinite	O
loan	O
from	O
Lincoln	O
Laboratory	O
.	O
</s>
<s>
In	O
this	O
setting	O
,	O
the	O
PDP-1	B-Device
quickly	O
replaced	O
the	O
TX-0	B-Device
as	O
the	O
favorite	O
machine	O
among	O
the	O
budding	O
hacker	O
culture	O
,	O
and	O
served	O
as	O
the	O
platform	O
for	O
a	O
long	O
list	O
of	O
computing	O
innovations	O
.	O
</s>
<s>
This	O
list	O
includes	O
one	O
of	O
the	O
earliest	O
digital	O
video	O
games	O
,	O
Spacewar	O
!,	O
the	O
first	O
text	B-Application
editor	I-Application
,	O
the	O
first	O
word	B-General_Concept
processor	I-General_Concept
,	O
the	O
first	O
interactive	O
debugger	B-Application
,	O
the	O
first	O
credible	O
computer	B-Application
chess	I-Application
program	O
,	O
one	O
of	O
the	O
very	O
earliest	O
time-sharing	B-General_Concept
systems	I-General_Concept
(	O
BBN	B-Operating_System
Time-Sharing	I-Operating_System
System	I-Operating_System
)	O
,	O
and	O
some	O
of	O
the	O
earliest	O
computerized	O
music	O
.	O
</s>
<s>
At	O
the	O
Computer	B-Architecture
History	I-Architecture
Museum	O
TX-0	B-Device
alumni	O
reunion	O
in	O
1984	O
,	O
Gordon	O
Bell	O
said	O
DEC	O
's	O
products	O
developed	O
directly	O
from	O
the	O
TX-2	B-Device
,	O
the	O
successor	O
to	O
the	O
TX-0	B-Device
which	O
had	O
been	O
developed	O
at	O
what	O
Bell	O
thought	O
was	O
a	O
bargain	O
price	O
at	O
the	O
time	O
,	O
about	O
.	O
</s>
<s>
At	O
the	O
same	O
meeting	O
,	O
Jack	O
Dennis	O
said	O
Ben	O
Gurley	O
's	O
design	O
for	O
the	O
PDP-1	B-Device
was	O
influenced	O
by	O
his	O
work	O
on	O
the	O
TX-0	B-Device
display	O
.	O
</s>
<s>
The	O
PDP-1	B-Device
sold	O
in	O
basic	O
form	O
for	O
(	O
equivalent	O
to	O
in	O
)	O
.	O
</s>
<s>
BBN	O
's	O
system	O
was	O
quickly	O
followed	O
by	O
orders	O
from	O
Lawrence	O
Livermore	O
and	O
Atomic	O
Energy	O
of	O
Canada	O
(	O
AECL	O
)	O
,	O
and	O
eventually	O
53	O
PDP-1s	B-Device
were	O
delivered	O
until	O
production	O
ended	O
in	O
1969	O
.	O
</s>
<s>
MIT	O
's	O
example	O
was	O
donated	O
to	O
The	O
Computer	O
Museum	O
,	O
Boston	O
,	O
and	O
from	O
there	O
ended	O
up	O
at	O
the	O
Computer	B-Architecture
History	I-Architecture
Museum	O
(	O
CHM	O
)	O
.	O
</s>
<s>
A	O
late	O
version	O
of	O
Spacewar	B-Application
!	I-Application
</s>
<s>
PDP-1	B-Device
#44	O
was	O
found	O
in	O
a	O
barn	O
in	O
Wichita	O
,	O
Kansas	O
in	O
1988	O
,	O
apparently	O
formerly	O
owned	O
by	O
one	O
of	O
the	O
many	O
aviation	O
companies	O
in	O
the	O
area	O
,	O
and	O
rescued	O
for	O
the	O
Digital	O
Historical	O
Collection	O
,	O
also	O
eventually	O
ending	O
up	O
at	O
the	O
CHM	O
.	O
</s>
<s>
The	O
launch	O
of	O
the	O
PDP-1	B-Device
marked	O
a	O
radical	O
shift	O
in	O
the	O
philosophy	O
of	O
computer	O
design	O
:	O
it	O
is	O
the	O
first	O
commercial	O
computer	O
that	O
focuses	O
on	O
interaction	O
with	O
the	O
user	O
rather	O
than	O
just	O
the	O
efficient	O
use	O
of	O
computer	O
cycles	O
.	O
</s>
<s>
The	O
first	O
ever	O
reference	O
to	O
malicious	O
hacking	O
is	O
'	O
telephone	O
hackers	O
 '	O
in	O
MIT	O
's	O
student	O
newspaper	O
,	O
The	O
Tech	O
of	O
hackers	O
tying	O
up	O
the	O
lines	O
with	O
Harvard	O
,	O
configuring	O
the	O
PDP-1	B-Device
to	O
make	O
free	O
calls	O
,	O
war	O
dialing	O
and	O
accumulating	O
large	O
phone	O
bills	O
.	O
</s>
<s>
The	O
PDP-1	B-Device
uses	O
punched	O
paper	O
tape	O
as	O
its	O
primary	O
storage	O
medium	O
.	O
</s>
<s>
Unlike	O
punched	B-Architecture
card	I-Architecture
decks	O
,	O
which	O
could	O
be	O
sorted	O
and	O
re-ordered	O
,	O
paper	O
tape	O
is	O
difficult	O
to	O
physically	O
edit	O
.	O
</s>
<s>
This	O
inspired	O
the	O
creation	O
of	O
text-editing	O
programs	O
such	O
as	O
Expensive	B-Application
Typewriter	I-Application
and	O
TECO	B-Application
.	O
</s>
<s>
Because	O
it	O
is	O
equipped	O
with	O
online	O
and	O
offline	O
printers	O
that	O
were	O
based	O
on	O
IBM	O
electric	O
typewriter	O
mechanisms	O
,	O
it	O
is	O
capable	O
of	O
what	O
,	O
in	O
1980s	O
terminology	O
,	O
would	O
be	O
called	O
"	O
letter-quality	O
printing	O
"	O
and	O
therefore	O
inspired	O
TJ-2	B-Protocol
,	O
arguably	O
the	O
first	O
word	B-General_Concept
processor	I-General_Concept
.	O
</s>
<s>
It	O
uses	O
an	O
IBM	O
Model	O
B	O
Electric	O
typewriter	O
mechanism	O
,	O
modified	O
by	O
the	O
addition	O
of	O
switches	O
to	O
detect	O
keypresses	O
,	O
and	O
solenoids	B-Algorithm
to	O
activate	O
the	O
typebars	O
.	O
</s>
<s>
Programs	O
commonly	O
use	O
color-coding	O
to	O
distinguish	O
user	B-General_Concept
input	I-General_Concept
from	O
machine	O
responses	O
.	O
</s>
<s>
Offline	O
devices	O
are	O
typically	O
Friden	B-Application
Flexowriters	I-Application
that	O
have	O
been	O
specially	O
built	O
to	O
operate	O
with	O
the	O
FIO-DEC	O
character	O
coding	O
used	O
by	O
the	O
PDP-1	B-Device
.	O
</s>
<s>
However	O
,	O
Flexowriters	B-Application
are	O
highly	O
reliable	O
and	O
were	O
often	O
used	O
for	O
long	O
unattended	O
printing	O
sessions	O
.	O
</s>
<s>
Flexowriters	B-Application
have	O
electromechanical	O
paper	O
tape	O
punches	O
and	O
readers	O
which	O
operate	O
synchronously	O
with	O
the	O
typewriter	O
mechanism	O
.	O
</s>
<s>
A	O
typical	O
PDP-1	B-Device
operating	O
procedure	O
is	O
to	O
output	O
text	O
to	O
punched	O
paper	O
tape	O
using	O
the	O
PDP-1	B-Device
'	O
s	O
"	O
high	O
speed	O
"	O
(	O
60-character-per-second	O
)	O
Teletype	O
model	O
BRPE	O
punch	O
,	O
then	O
to	O
hand	O
carry	O
the	O
tape	O
to	O
a	O
Flexowriter	B-Application
for	O
offline	O
printing	O
.	O
</s>
<s>
In	O
later	O
years	O
,	O
DECtape	O
drives	O
were	O
added	O
to	O
some	O
PDP-1	B-Device
systems	O
,	O
as	O
a	O
more	O
convenient	O
method	O
of	O
backing	O
up	O
programs	O
and	O
data	O
,	O
and	O
to	O
enable	O
early	O
time-sharing	B-General_Concept
.	O
</s>
<s>
Early	O
hard	B-Device
disks	I-Device
were	O
expensive	O
and	O
notoriously	O
unreliable	O
;	O
if	O
available	O
and	O
working	O
,	O
they	O
are	O
used	O
primarily	O
for	O
speed	O
of	O
swapping	O
,	O
and	O
not	O
for	O
permanent	O
file	O
storage	O
.	O
</s>
<s>
The	O
Type	O
30	O
Precision	O
CRT	B-Device
display	I-Device
is	O
a	O
point	O
plotting	O
display	O
device	O
capable	O
of	O
addressing	O
1024	O
by	O
1024	O
addressable	O
locations	O
at	O
a	O
rate	O
of	O
20,000	O
points	O
per	O
second	O
.	O
</s>
<s>
A	O
light	B-Device
pen	I-Device
can	O
be	O
used	O
with	O
the	O
Type	O
30	O
to	O
pick	O
points	O
on	O
the	O
display	O
.	O
</s>
<s>
MIT	O
hackers	O
also	O
used	O
the	O
PDP-1	B-Device
for	O
playing	O
music	O
in	O
four-part	O
harmony	O
,	O
using	O
some	O
special	O
hardware	O
–	O
four	O
flip-flops	B-General_Concept
directly	O
controlled	O
by	O
the	O
processor	O
(	O
the	O
audio	O
signal	O
is	O
filtered	O
with	O
simple	O
RC	B-Algorithm
filters	I-Algorithm
)	O
.	O
</s>
<s>
Music	O
was	O
prepared	O
via	O
Peter	O
Samson	O
's	O
Harmony	B-Language
Compiler	I-Language
,	O
a	O
sophisticated	O
text-based	O
program	O
with	O
some	O
features	O
specifically	O
oriented	O
toward	O
the	O
efficient	O
coding	O
of	O
baroque	O
music	O
.	O
</s>
<s>
Several	O
hours	O
of	O
music	O
were	O
prepared	O
for	O
it	O
,	O
including	O
Bach	O
fugues	B-Algorithm
,	O
all	O
of	O
Mozart	O
's	O
Eine	O
kleine	O
Nachtmusik	O
,	O
the	O
Ode	O
to	O
Joy	O
movement	O
concluding	O
Beethoven	O
's	O
Symphony	O
No	O
.	O
</s>
<s>
Only	O
three	O
PDP-1	B-Device
computers	O
are	O
still	O
known	O
to	O
exist	O
,	O
and	O
all	O
three	O
are	O
in	O
the	O
collection	O
of	O
the	O
Computer	B-Architecture
History	I-Architecture
Museum	O
(	O
CHM	O
)	O
.	O
</s>
<s>
One	O
is	O
the	O
prototype	O
formerly	O
used	O
at	O
MIT	O
,	O
and	O
the	O
other	O
two	O
are	O
production	O
PDP-1C	O
machines	O
.	O
</s>
<s>
One	O
of	O
the	O
latter	O
,	O
serial	O
number	O
55	O
(	O
the	O
last	O
PDP-1	B-Device
made	O
)	O
has	O
been	O
restored	O
to	O
working	O
order	O
,	O
is	O
on	O
exhibit	O
,	O
and	O
is	O
demonstrated	O
on	O
two	O
Saturdays	O
every	O
month	O
.	O
</s>
<s>
the	O
game	O
Spacewar	B-Application
!	I-Application
</s>
<s>
Software	O
simulations	O
of	O
the	O
PDP-1	B-Device
exist	O
in	O
SIMH	B-Application
and	O
MESS	O
,	O
hardware	O
recreation	O
through	O
FPGA	B-Architecture
exists	O
for	O
the	O
MiSTer	B-Device
project	O
as	O
well	O
,	O
and	O
binary	B-Algorithm
image	I-Algorithm
paper	O
tapes	O
of	O
the	O
software	O
exist	O
in	O
the	O
bitsavers.org	O
archives	O
.	O
</s>
