<s>
New	O
Implementation	O
of	O
LISP	B-Language
(	O
NIL	B-Language
)	O
is	O
a	O
programming	O
language	O
,	O
a	O
dialect	O
of	O
the	O
language	O
Lisp	B-Language
,	O
developed	O
at	O
the	O
Massachusetts	O
Institute	O
of	O
Technology	O
(	O
MIT	O
)	O
during	O
the	O
1970s	O
,	O
and	O
intended	O
to	O
be	O
the	O
successor	O
to	O
the	O
language	O
Maclisp	B-Language
.	O
</s>
<s>
It	O
is	O
a	O
32-bit	O
implementation	O
,	O
and	O
was	O
in	O
part	O
a	O
response	O
to	O
Digital	O
Equipment	O
Corporation	O
's	O
(	O
DEC	O
)	O
VAX	B-Device
computer	O
.	O
</s>
<s>
The	O
project	O
was	O
headed	O
by	O
Jon	O
L	O
White	O
,	O
with	O
a	O
stated	O
goal	O
of	O
maintaining	O
compatibility	O
with	O
MacLisp	B-Language
while	O
fixing	O
many	O
of	O
its	O
problems	O
.	O
</s>
<s>
The	O
Lisp	B-Language
language	I-Language
was	O
invented	O
in	O
1958	O
by	O
John	O
McCarthy	O
while	O
he	O
was	O
at	O
Massachusetts	O
Institute	O
of	O
Technology	O
(	O
MIT	O
)	O
.	O
</s>
<s>
From	O
its	O
inception	O
,	O
Lisp	B-Language
was	O
closely	O
connected	O
with	O
the	B-Application
artificial	I-Application
intelligence	I-Application
(	O
AI	B-Application
)	O
research	O
community	O
,	O
especially	O
on	O
PDP-10	B-Device
systems	O
.	O
</s>
<s>
The	O
36-bit	O
word	O
size	O
of	O
the	O
PDP-6	B-Device
and	O
PDP-10	B-Device
was	O
influenced	O
by	O
the	O
usefulness	O
of	O
having	O
two	O
Lisp	B-Language
18-bit	B-General_Concept
pointers	O
in	O
one	O
word	O
:	O
"	O
The	O
PDP-6	B-Device
project	O
started	O
in	O
early	O
1963	O
,	O
as	O
a	O
24-bit	O
machine	O
.	O
</s>
<s>
It	O
grew	O
to	O
36	O
bits	O
for	O
LISP	B-Language
,	O
a	O
design	O
goal.	O
"	O
</s>
<s>
Lisp	B-Language
was	O
used	O
as	O
the	O
implementation	O
of	O
the	O
programming	O
language	O
Micro	O
Planner	B-Application
that	O
was	O
the	O
foundation	O
for	O
the	O
famous	O
AI	B-Application
system	O
SHRDLU	O
.	O
</s>
<s>
Lisp	B-Language
,	O
in	O
particular	O
Maclisp	B-Language
(	O
so	O
named	O
because	O
it	O
originated	O
at	O
MIT	O
's	O
project	O
MAC	O
)	O
was	O
also	O
used	O
to	O
implement	O
the	O
Macsyma	B-Language
computer	B-General_Concept
algebra	I-General_Concept
system	I-General_Concept
.	O
</s>
<s>
In	O
the	O
1970s	O
,	O
as	O
AI	B-Application
research	I-Application
spawned	O
commercial	O
offshoots	O
,	O
the	O
performance	O
of	O
extant	O
Lisp	B-Language
systems	O
became	O
a	O
growing	O
problem	O
.	O
</s>
<s>
Partly	O
because	O
of	O
garbage	B-General_Concept
collection	I-General_Concept
(	O
Lisp	B-Language
would	O
use	O
stop-and-copy	O
garbage	B-General_Concept
collection	I-General_Concept
of	O
its	O
single	O
heap	O
for	O
memory	B-General_Concept
allocation	I-General_Concept
)	O
and	O
partly	O
because	O
of	O
its	O
representation	O
of	O
internal	O
structures	O
,	O
Lisp	B-Language
became	O
difficult	O
to	O
run	O
on	O
the	O
memory-limited	O
stock	O
computer	B-Architecture
hardware	I-Architecture
of	O
the	O
day	O
.	O
</s>
<s>
This	O
led	O
to	O
creating	O
Lisp	B-Operating_System
machines	I-Operating_System
:	O
dedicated	O
hardware	B-Architecture
for	O
running	O
Lisp	B-Language
environments	O
and	O
programs	O
.	O
</s>
<s>
An	O
alternative	O
was	O
to	O
use	O
the	O
more	O
powerful	O
commodity	O
hardware	B-Architecture
which	O
was	O
becoming	O
available	O
,	O
especially	O
the	O
Digital	O
Equipment	O
Corporation	O
(	O
DEC	O
)	O
VAX	B-Device
.	O
</s>
<s>
NIL	B-Language
was	O
an	O
implementation	O
of	O
Lisp	B-Language
developed	O
at	O
MIT	O
in	O
the	O
mid	O
to	O
late	O
1970s	O
,	O
and	O
intended	O
to	O
be	O
a	O
modern	O
successor	O
to	O
Maclisp	B-Language
that	O
was	O
able	O
to	O
run	O
on	O
stock	O
hardware	B-Architecture
,	O
in	O
contrast	O
to	O
Lisp	B-Language
Machine	I-Language
Lisp	I-Language
for	O
the	O
Lisp	B-Operating_System
machines	I-Operating_System
.	O
</s>
<s>
"	O
Originally	O
designed	O
as	O
the	O
first	O
modern	O
Lisp	B-Language
dialect	O
on	O
stock	O
hardware	B-Architecture
after	O
the	O
development	O
of	O
Lisp	B-Language
machine	I-Language
Lisp	I-Language
at	O
MIT	O
,	O
it	O
went	O
on	O
to	O
become	O
one	O
of	O
the	O
main	O
influences	O
on	O
the	O
design	O
of	O
Common	O
Lisp.	O
"	O
</s>
<s>
(	O
pg	O
63/294	O
of	O
)	O
Since	O
the	O
users	O
of	O
the	O
Macsyma	B-Language
program	O
represented	O
a	O
large	O
potential	O
user	O
base	O
for	O
NIL	B-Language
,	O
it	O
was	O
necessary	O
that	O
NIL	B-Language
would	O
be	O
a	O
large	O
,	O
complex	O
system	O
,	O
and	O
that	O
speed	O
would	O
be	O
imperative	O
.	O
</s>
<s>
For	O
example	O
,	O
high-speed	O
bignums	B-Algorithm
was	O
a	O
requirement	O
to	O
support	O
Macsyma	B-Language
,	O
since	O
NIL	B-Language
would	O
be	O
a	O
failure	O
with	O
slow	O
bignums	B-Algorithm
.	O
</s>
<s>
Consequently	O
,	O
NIL	B-Language
ended	O
up	O
with	O
a	O
large	O
base	O
of	O
VAX	B-Device
assembly	B-Language
language	I-Language
.	O
</s>
<s>
Concurrent	O
with	O
the	O
effort	O
to	O
write	O
NIL	B-Language
,	O
a	O
research	O
group	O
at	O
Stanford	O
University	O
and	O
Lawrence	O
Livermore	O
National	O
Laboratory	O
headed	O
by	O
Richard	O
P	O
.	O
Gabriel	O
were	O
investigating	O
the	O
design	O
of	O
a	O
Lisp	B-Language
to	O
run	O
on	O
the	O
S-1	O
Mark	O
IIA	O
supercomputer	B-Architecture
,	O
S-1	B-Language
Lisp	I-Language
.	O
</s>
<s>
That	O
Lisp	B-Language
was	O
never	O
fully	O
functional	B-Language
,	O
but	O
was	O
a	O
test	O
bed	O
for	O
implementing	O
advanced	O
compiler	B-Language
methods	O
in	O
a	O
Lisp	B-Language
.	O
</s>
<s>
Eventually	O
the	O
S-1	O
and	O
NIL	B-Language
groups	O
began	O
collaborating	O
.	O
</s>
<s>
Although	O
unsuccessful	O
in	O
meeting	O
its	O
goals	O
as	O
a	O
used	O
language	O
,	O
NIL	B-Language
was	O
important	O
in	O
several	O
ways	O
.	O
</s>
<s>
First	O
,	O
it	O
brought	O
together	O
Jon	O
L	O
.	O
White	O
,	O
Guy	O
L	O
.	O
Steele	O
Jr.	O
,	O
and	O
Richard	O
P	O
.	O
Gabriel	O
,	O
who	O
were	O
later	O
to	O
define	O
Common	B-Language
Lisp	I-Language
.	O
</s>
<s>
Second	O
,	O
Jonathan	O
Rees	O
worked	O
on	O
part	O
of	O
the	O
NIL	B-Language
project	O
during	O
a	O
year	O
away	O
from	O
Yale	O
University	O
.	O
</s>
<s>
On	O
returning	O
to	O
Yale	O
,	O
he	O
was	O
hired	O
by	O
the	O
computer	B-General_Concept
science	I-General_Concept
department	O
to	O
write	O
a	O
new	O
Lisp	B-Language
,	O
which	O
became	O
the	O
optimizing	O
,	O
native	O
code	O
Scheme	B-Language
system	O
named	O
T	B-Language
.	O
In	O
part	O
,	O
NIL	B-Language
begat	O
this	O
name	O
,	O
since	O
"	O
T	B-Language
is	O
not	O
NIL	B-Language
"	O
.	O
</s>
