<s>
The	O
IBM	B-Device
System/360	I-Device
Model	I-Device
25	I-Device
is	O
a	O
low-end	O
member	O
of	O
the	O
IBM	B-Application
System/360	I-Application
family	O
.	O
</s>
<s>
It	O
was	O
announced	O
on	O
January	O
3	O
,	O
1968	O
,	O
3	O
years	O
before	O
the	O
IBM	B-Device
System/360	I-Device
Model	I-Device
22	I-Device
,	O
</s>
<s>
At	O
a	O
time	O
when	O
lower	O
priced	O
alternatives	O
,	O
such	O
as	O
service	O
bureaus	O
-	O
by	O
1968	O
,	O
there	O
were	O
32	O
such	O
service	O
bureaus	O
serving	O
the	O
US	O
National	O
Institutes	O
of	O
Health	O
(	O
NIH	O
)	O
alone	O
-	O
and	O
prior	O
generation	O
systems	O
,	O
such	O
as	O
the	O
Honeywell	B-Device
200	I-Device
,	O
a	O
competitor	O
to	O
IBM	O
's	O
own	O
IBM	B-Device
1401	I-Device
,	O
were	O
available	O
,	O
this	O
model	O
provided	O
a	O
stop-gap	O
measure	O
.	O
</s>
<s>
The	O
base	O
Model	O
25	O
implements	O
the	O
System/360	B-Device
standard	O
and	O
commercial	O
instruction	O
sets	O
.	O
</s>
<s>
The	O
Model	O
25	O
logic	O
is	O
built	O
on	O
IBM	B-Algorithm
SLT	I-Algorithm
modules	O
mounted	O
on	O
pluggable	O
cards	O
,	O
which	O
are	O
plugged	O
into	O
printed	O
circuit	O
boards	O
.	O
</s>
<s>
The	O
Model	O
25	O
is	O
the	O
first	O
IBM	O
system	O
to	O
store	O
its	O
microcode	B-Device
in	O
a	O
rewritable	O
memory	O
,	O
called	O
the	O
control	O
storage	O
.	O
</s>
<s>
There	O
is	O
also	O
a	O
small	O
part	O
of	O
the	O
core	O
storage	O
that	O
is	O
used	O
to	O
store	O
the	O
contents	O
of	O
registers	O
accessible	O
by	O
software	O
,	O
as	O
well	O
as	O
data	O
used	O
by	O
the	O
microcode	B-Device
.	O
</s>
<s>
The	O
Model	O
25	O
also	O
has	O
a	O
64-byte	O
high-speed	O
(	O
180ns	O
)	O
SLT	O
Local	O
Storage	O
,	O
used	O
by	O
the	O
microcode	B-Device
.	O
</s>
<s>
One	O
1403	B-Device
Prnter	O
Model	O
2	O
or	O
7	O
.	O
</s>
<s>
After	O
the	O
original	O
announcement	O
the	O
IBM	B-Device
1403	I-Device
model	O
N1	O
was	O
added	O
.	O
</s>
<s>
The	O
Model	O
25	O
has	O
a	O
standard	O
attachment	O
for	O
connection	O
of	O
a	O
1052	B-Device
Model	O
7	O
console	O
printer-keyboard	O
,	O
which	O
is	O
used	O
as	O
the	O
operator	O
console	O
.	O
</s>
<s>
Optionally	O
,	O
the	O
Model	O
25	O
can	O
have	O
a	O
standard	O
System/360	B-Device
I/O	B-Device
channel	I-Device
,	O
that	O
can	O
be	O
either	O
a	O
byte-multiplexor	O
or	O
a	O
selector	O
channel	O
.	O
</s>
<s>
For	O
the	O
most	O
commonly	O
used	O
peripherals	O
,	O
such	O
as	O
a	O
2540	B-Device
or	O
2560	O
card	O
reader-punch	O
,	O
a	O
1403	B-Device
printer	O
,	O
or	O
2311	B-Device
or	O
2314	B-Device
disk	O
drives	O
,	O
optional	O
internal	O
attachments	O
are	O
provided	O
.	O
</s>
<s>
Most	O
unusual	O
about	O
the	O
360/25	O
was	O
a	O
feature	O
somewhat	O
analogous	O
to	O
the	O
IBM	B-Device
System/360	I-Device
Model	I-Device
44	I-Device
's	O
integrated	O
single	O
disk	O
storage	O
drive	O
,	O
namely	O
an	O
integrated	O
attachment	O
.	O
</s>
<s>
The	O
Model	O
25	O
provides	O
an	O
optional	O
compatibility	O
feature	O
that	O
helps	O
users	O
of	O
IBM	B-Device
1400	I-Device
series	I-Device
computers	O
migrate	O
to	O
System/360	B-Device
.	O
</s>
<s>
With	O
the	O
additional	O
Compatibility	O
Feature	O
hardware	O
and	O
Compatibility	O
Support	O
software	O
under	O
DOS/360	B-Application
,	O
the	O
IBM	O
1401/1440/1460	O
object	O
programs	O
can	O
be	O
run	O
in	O
the	O
emulation	O
mode	O
,	O
with	O
little	O
or	O
no	O
reprogramming	O
.	O
</s>
<s>
The	O
standard	O
set	O
of	O
peripherals	O
is	O
available	O
,	O
although	O
by	O
this	O
time	O
customers	O
had	O
found	O
their	O
way	O
to	O
IBM-compatible	B-Device
alternatives	O
.	O
</s>
<s>
A	O
typical	O
System/360	B-Device
Model	O
25	O
configuration	O
consists	O
of	O
:	O
</s>
<s>
The	O
typical	O
operating	O
system	O
for	O
the	O
Model	O
25	O
was	O
DOS/360	B-Application
,	O
which	O
was	O
loaded	O
from	O
disk	O
.	O
</s>
<s>
Less	O
common	O
was	O
TOS/360	B-Application
,	O
which	O
was	O
loaded	O
from	O
tape	O
,	O
and	O
,	O
rarely	O
,	O
BOS/360	B-Application
,	O
which	O
was	O
loaded	O
from	O
punched	O
cards	O
.	O
</s>
<s>
Programming	O
was	O
mostly	O
in	O
the	O
COBOL	B-Application
,	O
RPG	B-Language
and	O
Assembler	B-Language
languages	I-Language
for	O
the	O
commercial	O
applications	O
that	O
were	O
the	O
predominant	O
uses	O
of	O
this	O
computer	O
,	O
but	O
Fortran	B-Application
IV	I-Application
and	O
could	O
also	O
be	O
used	O
for	O
the	O
scientific	O
and	O
engineering	O
applications	O
,	O
and	O
PL/I	B-Language
was	O
available	O
.	O
</s>
