<s>
The	O
PDP-15	B-Device
was	O
the	O
fifth	O
and	O
last	O
of	O
the	O
18-bit	B-General_Concept
minicomputers	B-Architecture
produced	O
by	O
Digital	O
Equipment	O
Corporation	O
.	O
</s>
<s>
The	O
PDP-1	B-Device
was	O
first	O
delivered	O
in	O
December	O
1959	O
and	O
the	O
first	O
PDP-15	B-Device
was	O
delivered	O
in	O
February	O
1970	O
.	O
</s>
<s>
More	O
than	O
400	O
of	O
these	O
successors	O
to	O
the	O
PDP-9	B-Device
(	O
and	O
9/L	O
)	O
were	O
ordered	O
within	O
the	O
first	O
eight	O
months	O
.	O
</s>
<s>
In	O
addition	O
to	O
operating	B-General_Concept
systems	I-General_Concept
,	O
the	O
PDP-15	B-Device
had	O
compilers	O
for	O
Fortran	B-Application
and	O
ALGOL	B-Language
.	O
</s>
<s>
The	O
18-bit	B-General_Concept
PDP	O
systems	O
preceding	O
the	O
PDP-15	B-Device
were	O
named	O
PDP-1	B-Device
,	O
PDP-4	B-Device
,	O
PDP-7	B-Device
&	O
PDP-9	B-Device
.	O
</s>
<s>
The	O
last	O
PDP-15	B-Device
was	O
produced	O
in	O
1979	O
.	O
</s>
<s>
The	O
PDP-15	B-Device
was	O
DEC	O
's	O
only	O
18-bit	B-General_Concept
machine	O
constructed	O
from	O
TTL	B-General_Concept
integrated	O
circuits	O
rather	O
than	O
discrete	O
transistors	O
,	O
and	O
,	O
like	O
every	O
DEC	O
18-bit	B-General_Concept
system	O
could	O
be	O
equipped	O
with	O
:	O
</s>
<s>
The	O
PDP-15	B-Device
models	O
offered	O
by	O
DEC	O
were	O
:	O
</s>
<s>
PDP-15/50	O
:	O
</s>
<s>
PDP-15/76	O
:	O
15/40	O
plus	O
PDP-11	B-Device
frontend	O
.	O
</s>
<s>
The	O
PDP-15/76	O
was	O
a	O
dual-processor	O
system	O
that	O
shared	O
memory	O
with	O
an	O
attached	O
05	O
..	O
</s>
<s>
The	O
PDP-11	B-Device
served	O
as	O
a	O
peripheral	O
processor	O
and	O
enabled	O
use	O
of	O
Unibus	O
peripherals	O
.	O
</s>
<s>
DECsys	O
,	O
RSX-15	O
,	O
and	O
XVM/RSX	O
were	O
the	O
operating	B-General_Concept
systems	I-General_Concept
supplied	O
by	O
DEC	O
for	O
the	O
PDP-15	B-Device
.	O
</s>
<s>
A	O
batch	B-General_Concept
processing	I-General_Concept
monitor	B-Application
(	O
BOSS-15	O
:	O
Batch	O
Operating	O
Software	O
System	O
)	O
was	O
also	O
available	O
.	O
</s>
<s>
The	O
first	O
DEC-supplied	O
mass-storage	O
operating	B-General_Concept
system	I-General_Concept
available	O
for	O
the	O
PDP-15	B-Device
was	O
DECsys	O
,	O
an	O
interactive	O
single-user	O
system	O
.	O
</s>
<s>
A	O
second	O
DECtape	O
was	O
used	O
as	O
a	O
scratch	O
tape	O
by	O
the	O
assembler	O
and	O
the	O
Fortran	B-Application
compiler	O
.	O
</s>
<s>
Once	O
XVM/RSX	O
was	O
released	O
,	O
DEC	O
facilitated	O
that	O
"	O
a	O
PDP-15	B-Device
can	O
be	O
field-upgraded	O
to	O
XVM	O
"	O
but	O
it	O
required	O
"	O
the	O
addition	O
of	O
the	O
XM15	O
memory	O
processor.	O
"	O
</s>
<s>
The	O
RSX-11	B-Application
operating	B-General_Concept
system	I-General_Concept
began	O
as	O
a	O
port	O
of	O
RSX-15	O
to	O
the	O
PDP-11	B-Device
,	O
although	O
it	O
later	O
diverged	O
significantly	O
in	O
terms	O
of	O
design	O
and	O
functionality	O
.	O
</s>
<s>
Later	O
versions	O
of	O
the	O
PDP-15	B-Device
could	O
run	O
a	O
real-time	O
multi-user	O
OS	O
called	O
XVM/RSX	O
,	O
an	O
outgrowth	O
of	O
RSX-15	O
.	O
</s>
<s>
XVM	O
Support	O
for	O
the	O
PDP-15/76	O
included	O
using	O
an	O
RK05	B-Device
disk	O
drive	O
.	O
</s>
<s>
One	O
other	O
operating	B-General_Concept
system	I-General_Concept
,	O
developed	O
on	O
the	O
PDP-7	B-Device
,	O
was	O
also	O
available	O
for	O
the	O
PDP-15	B-Device
:	O
</s>
