<s>
The	O
Standard	B-Device
Modular	I-Device
System	I-Device
(	O
SMS	O
)	O
is	O
a	O
system	O
of	O
standard	O
transistorized	O
circuit	O
boards	O
and	O
mounting	O
racks	O
developed	O
by	O
IBM	O
in	O
the	O
late	O
1950s	O
,	O
originally	O
for	O
the	O
IBM	B-Device
7030	I-Device
Stretch	I-Device
.	O
</s>
<s>
They	O
were	O
used	O
throughout	O
IBM	O
's	O
second-generation	O
computers	O
,	O
peripherals	O
,	O
the	O
7000	B-Device
series	I-Device
,	O
the	O
1400	B-Device
series	I-Device
,	O
and	O
the	O
1620	B-Device
.	O
</s>
<s>
SMS	O
was	O
superseded	O
by	O
Solid	B-Algorithm
Logic	I-Algorithm
Technology	I-Algorithm
(	O
SLT	B-Algorithm
)	O
introduced	O
with	O
System/360	B-Application
in	O
1964	O
,	O
however	O
they	O
remained	O
in	O
use	O
with	O
legacy	O
systems	O
through	O
the	O
1970s	O
.	O
</s>
<s>
Many	O
IBM	O
peripheral	O
devices	O
that	O
are	O
part	O
of	O
System/360	B-Application
,	O
but	O
were	O
adapted	O
from	O
second-generation	O
designs	O
,	O
continued	O
to	O
use	O
SMS	O
circuitry	O
instead	O
of	O
the	O
newer	O
SLT	B-Algorithm
.	O
</s>
<s>
These	O
included	O
the	O
240x-series	B-Device
tape	I-Device
drives	I-Device
and	O
controllers	O
,	O
the	O
2540	B-Device
card	I-Device
reader/punch	I-Device
and	O
1403N1	B-Device
printer	I-Device
,	O
and	O
the	O
2821	B-Device
Integrated	I-Device
Control	I-Device
Unit	I-Device
for	O
the	O
1403	O
and	O
2540	O
.	O
</s>
<s>
A	O
few	O
SMS	O
cards	O
used	O
in	O
System/360	B-Application
peripheral	O
devices	O
even	O
have	O
SLT-type	O
hybrid	O
ICs	O
mounted	O
on	O
them	O
(	O
see	O
right	O
)	O
.	O
</s>
<s>
Part	O
of	O
the	O
reason	O
for	O
the	O
growth	O
was	O
that	O
multiple	O
digital	B-General_Concept
logic	B-General_Concept
families	I-General_Concept
were	O
implemented	O
(	O
ECL	O
,	O
RTL	O
,	O
DTL	O
,	O
etc	O
.	O
)	O
</s>
