<s>
In	O
theoretical	O
computer	O
science	O
,	O
a	O
pointer	B-Application
machine	I-Application
is	O
an	O
atomistic	O
abstract	B-Application
computational	I-Application
machine	I-Application
model	O
akin	O
to	O
the	O
random-access	B-Application
machine	I-Application
.	O
</s>
<s>
A	O
pointer	B-Application
algorithm	I-Application
could	O
also	O
be	O
an	O
algorithm	O
restricted	O
to	O
the	O
pointer	B-Application
machine	I-Application
model	O
.	O
</s>
<s>
Depending	O
on	O
the	O
type	O
,	O
a	O
pointer	B-Application
machine	I-Application
may	O
be	O
called	O
a	O
linking	O
automaton	O
,	O
a	O
KU-machine	O
,	O
an	O
SMM	O
,	O
an	O
atomistic	O
LISP	O
machine	O
,	O
a	O
tree-pointer	O
machine	O
,	O
etc	O
.	O
</s>
<s>
From	O
its	O
"	O
read-only	O
tape	O
"	O
(	O
or	O
equivalent	O
)	O
a	O
pointer	B-Application
machine	I-Application
receives	O
input	O
—	O
bounded	O
symbol-sequences	O
(	O
"	O
words	O
"	O
)	O
made	O
of	O
at	O
least	O
two	O
symbols	O
e.g.	O
</s>
<s>
Pointer	B-Application
machines	I-Application
cannot	O
do	O
arithmetic	O
in	O
normal	O
ways	O
.	O
</s>
<s>
Both	O
Gurevich	O
and	O
Ben-Amram	O
list	O
a	O
number	O
of	O
very	O
similar	O
"	O
atomistic	O
"	O
models	O
of	O
"	O
abstract	B-Application
machines	I-Application
"	O
;	O
Ben-Amram	O
believes	O
that	O
the	O
6	O
"	O
atomistic	O
models	O
"	O
must	O
be	O
distinguished	O
from	O
"	O
High-level	O
"	O
models	O
.	O
</s>
<s>
General	O
atomistic	O
pointer	B-Application
machines	I-Application
,	O
</s>
<s>
The	O
fact	O
that	O
,	O
in	O
§3	O
and	O
§4	O
(	O
pp.494	O
–	O
497	O
)	O
,	O
Schönhage	O
himself	O
(	O
1980	O
)	O
demonstrates	O
the	O
real-time	O
equivalences	O
of	O
his	O
two	O
random-access	B-Application
machine	I-Application
models	O
"	O
RAM0	O
"	O
and	O
"	O
RAM1	O
"	O
leads	O
one	O
to	O
question	O
the	O
necessity	O
of	O
the	O
SMM	O
for	O
complexity	O
studies	O
.	O
</s>
<s>
It	O
is	O
quite	O
unlike	O
the	O
register	B-Application
machine	I-Application
model	O
and	O
other	O
common	O
computational	O
models	O
e.g.	O
</s>
<s>
the	O
tape-based	O
Turing	B-Architecture
machine	I-Architecture
or	O
the	O
labeled	O
holes	O
and	O
indistinguishable	O
pebbles	O
of	O
the	O
counter	B-Application
machine	I-Application
.	O
</s>
<s>
The	O
computer	O
consists	O
of	O
a	O
fixed	O
alphabet	O
of	O
input	O
symbols	O
,	O
and	O
a	O
mutable	O
directed	O
graph	O
(	O
aka	O
a	O
state	B-Application
diagram	I-Application
)	O
with	O
its	O
arrows	O
labelled	O
by	O
alphabet	O
symbols	O
.	O
</s>
<s>
This	O
instruction	O
serves	O
the	O
same	O
purpose	O
as	O
its	O
counterpart	O
in	O
a	O
register	B-Application
machine	I-Application
or	O
Wang	O
b-machine	O
,	O
corresponding	O
to	O
a	O
Turing	B-Architecture
machine	I-Architecture
's	O
ability	O
to	O
jump	O
to	O
a	O
new	O
state	O
.	O
</s>
<s>
According	O
to	O
Schoenhage	O
,	O
Knuth	O
noted	O
that	O
the	O
SMM	O
model	O
coincides	O
with	O
a	O
special	O
type	O
of	O
"	O
linking	O
automata	O
"	O
briefly	O
explained	O
in	O
volume	O
one	O
of	O
The	B-General_Concept
Art	I-General_Concept
of	I-General_Concept
Computer	I-General_Concept
Programming	I-General_Concept
(	O
cf	O
.	O
</s>
<s>
An	O
additional	O
difference	O
is	O
that	O
the	O
KUM	O
was	O
intended	O
as	O
a	O
generalization	O
of	O
the	B-Architecture
Turing	I-Architecture
machine	I-Architecture
,	O
and	O
so	O
it	O
allows	O
the	O
currently	O
"	O
active	O
"	O
node	O
to	O
be	O
moved	O
around	O
the	O
graph	O
.	O
</s>
