<s>
They	O
were	O
the	O
first	O
three	O
models	O
of	O
the	O
IBM	B-Device
System/370	I-Device
line	O
of	O
computers	O
.	O
</s>
<s>
Three	O
months	O
later	O
a	O
fourth	O
IBM	B-Device
System/370	I-Device
,	O
the	O
Model	B-Device
145	I-Device
,	O
was	O
announced	O
.	O
</s>
<s>
Since	O
none	O
of	O
them	O
came	O
with	O
virtual	B-Architecture
memory	I-Architecture
,	O
"	O
which	O
was	O
to	O
be	O
a	O
hallmark	O
of	O
the	O
370	O
line	O
"	O
some	O
said	O
about	O
these	O
early	O
members	O
of	O
the	O
IBM	B-Device
System/370	I-Device
family	O
,	O
especially	O
about	O
the	O
165	O
&	O
155	O
,	O
that	O
they	O
were	O
not	O
"	O
the	O
real	O
370	O
line.	O
"	O
</s>
<s>
The	O
initially	O
announced	O
System/370	B-Device
Models	O
165	O
&	O
155	O
systems	O
were	O
in	O
many	O
ways	O
merely	O
improved	O
IBM	B-Application
System/360	I-Application
systems	O
.	O
</s>
<s>
Both	O
were	O
announced	O
to	O
"	O
run	O
under	O
proven	O
OS	B-Application
programming	O
support.	O
"	O
</s>
<s>
As	O
compared	O
to	O
the	O
360	O
,	O
their	O
basic	O
architecture	O
was	O
described	O
as	O
"	O
extended	O
,	O
but	O
not	O
redesigned	O
,	O
for	O
System/370	B-Device
.	O
</s>
<s>
The	O
IBM	B-Device
System/360	I-Device
Model	I-Device
85	I-Device
used	O
microcode	B-Device
to	O
control	O
instruction	O
execution	O
,	O
unlike	O
the	O
completely-hardwired	O
360/75	B-Device
and	O
360/91	B-Device
;	O
the	O
high-end	O
models	O
of	O
System/370	B-Device
were	O
also	O
microcoded	B-Device
.	O
</s>
<s>
Some	O
describe	O
the	O
360/85	B-Device
as	O
a	O
bridge	O
to	O
the	O
370/165	B-Device
.	O
</s>
<s>
In	O
1972	O
an	O
upgrade	O
option	O
was	O
announced	O
"	O
to	O
provide	O
the	O
hardware	O
necessary	O
to	O
operate	O
in	O
a	O
virtual	B-Architecture
memory	I-Architecture
mode.	O
"	O
</s>
<s>
709	B-Device
,	O
7040	B-Device
,	O
7044	B-Device
,	O
7094	B-Device
and	I-Device
7094	I-Device
II	I-Device
programs	O
.	O
</s>
<s>
The	O
IBM	O
7070/7074	O
Compatibility	O
Feature	O
allowed	O
the	O
165	O
to	O
"	O
run	O
7070	B-Device
and	O
7074	B-Device
programs	O
at	O
speeds	O
that	O
,	O
in	O
general	O
,	O
equal	O
or	O
exceed	O
those	O
of	O
the	O
original	O
systems	O
"	O
and	O
yet	O
"	O
not	O
affect	O
normal	O
operation	O
of	O
System/370.	O
"	O
</s>
<s>
Although	O
the	O
joint	O
155/165	O
announcement	O
did	O
not	O
have	O
the	O
word	O
virtual	O
,	O
there	O
were	O
multiple	O
references	O
to	O
(	O
physical	O
)	O
memory	O
,	O
storage	O
(	O
both	O
main	O
memory	O
and	O
disk	O
storage	O
)	O
,	O
and	O
cache	B-General_Concept
memory	I-General_Concept
under	O
the	O
name	O
"	O
buffer	O
"	O
.	O
</s>
