<s>
The	O
IBM	B-Device
M44/44X	I-Device
was	O
an	O
experimental	O
computer	O
system	O
from	O
the	O
mid-1960s	O
,	O
designed	O
and	O
operated	O
at	O
IBM	O
's	O
Thomas	O
J	O
.	O
Watson	O
Research	O
Center	O
at	O
Yorktown	O
Heights	O
,	O
New	O
York	O
.	O
</s>
<s>
It	O
was	O
based	O
on	O
a	O
modified	O
IBM	B-Device
7044	I-Device
(	O
the	O
'	O
M44	O
 '	O
)	O
,	O
and	O
simulated	O
multiple	O
7044	O
virtual	B-Architecture
machines	I-Architecture
(	O
the	O
'	O
44X	O
 '	O
)	O
,	O
using	O
both	O
hardware	O
and	O
software	O
.	O
</s>
<s>
This	O
was	O
a	O
groundbreaking	O
machine	O
,	O
used	O
to	O
explore	O
paging	B-Architecture
,	O
the	O
virtual	B-Architecture
machine	I-Architecture
concept	O
,	O
and	O
computer	O
performance	O
measurement	O
.	O
</s>
<s>
The	O
term	O
virtual	B-Architecture
machine	I-Architecture
probably	O
originated	O
with	O
the	O
M44/44X	B-Device
project	O
,	O
from	O
which	O
it	O
was	O
later	O
appropriated	O
by	O
the	O
CP-40	B-Application
team	O
to	O
replace	O
their	O
earlier	O
term	O
pseudo	O
machine	O
.	O
</s>
<s>
Unlike	O
CP-40	B-Application
and	O
later	O
CP/CMS	B-Application
control	O
programs	O
,	O
M44/44X	B-Device
did	O
not	O
implement	O
a	O
complete	O
simulation	O
of	O
the	O
underlying	O
hardware	O
(	O
i.e.	O
</s>
<s>
full	B-Architecture
virtualization	I-Architecture
)	O
.	O
</s>
<s>
CP-40	B-Application
project	O
leader	O
Robert	O
Creasy	O
observed	O
:	O
</s>
<s>
The	O
M44/44X	B-Device
"	O
was	O
about	O
as	O
much	O
of	O
a	O
virtual	B-Architecture
machine	I-Architecture
system	O
as	O
CTSS	B-Operating_System
–	O
which	O
is	O
to	O
say	O
that	O
it	O
was	O
close	O
enough	O
to	O
a	O
virtual	B-Architecture
machine	I-Architecture
system	O
to	O
show	O
that	O
'	O
close	O
enough	O
 '	O
did	O
not	O
count	O
.	O
</s>
<s>
I	O
never	O
heard	O
a	O
more	O
eloquent	O
argument	O
for	O
virtual	B-Architecture
machines	I-Architecture
than	O
from	O
Dave	O
Sayre	O
.	O
</s>
<s>
M44/44X	B-Device
"	O
implanted	O
the	O
idea	O
that	O
the	O
virtual	B-Architecture
machine	I-Architecture
concept	O
is	O
not	O
necessarily	O
less	O
efficient	O
than	O
more	O
conventional	O
approaches	O
"	O
a	O
core	O
assumption	O
in	O
the	O
CP/CMS	B-Application
architecture	O
,	O
and	O
one	O
that	O
ultimately	O
proved	O
very	O
successful	O
.	O
</s>
