<s>
The	O
SS-50	B-Architecture
bus	I-Architecture
was	O
an	O
early	O
computer	B-General_Concept
bus	I-General_Concept
designed	O
as	O
a	O
part	O
of	O
the	O
SWTPC	B-Device
6800	I-Device
Computer	O
System	O
that	O
used	O
the	O
Motorola	B-Device
6800	I-Device
CPU	O
.	O
</s>
<s>
The	O
SS-50	O
motherboard	B-Device
would	O
have	O
around	O
seven	O
50-pin	O
connectors	O
for	O
CPU	O
and	O
memory	O
boards	O
plus	O
eight	O
30-pin	O
connectors	O
for	O
I/O	O
boards	O
.	O
</s>
<s>
Some	O
of	O
the	O
early	O
boards	O
were	O
floppy	O
disk	O
systems	O
from	O
Midwest	O
Scientific	O
Instruments	O
,	O
Smoke	O
Signal	O
Broadcasting	O
,	O
and	O
Percom	B-Device
Data	I-Device
;	O
an	O
EPROM	O
programmer	O
from	O
the	O
Micro	O
Works	O
;	O
video	O
display	O
boards	O
from	O
Gimix	O
;	O
memory	O
boards	O
from	O
Seals	O
.	O
</s>
<s>
In	O
1979	O
SWTPC	O
modified	O
the	O
SS-50	B-Architecture
bus	I-Architecture
to	O
support	O
the	O
new	O
Motorola	O
MC6809	B-Device
processor	O
.	O
</s>
<s>
These	O
changes	O
were	O
compatible	O
with	O
most	O
existing	O
boards	O
and	O
this	O
upgrade	O
gave	O
the	O
SS-50	B-Architecture
Bus	I-Architecture
a	O
long	O
life	O
.	O
</s>
<s>
The	O
SS-50C	O
bus	O
,	O
the	O
S/09	O
version	O
of	O
the	O
SS-50	B-Architecture
bus	I-Architecture
,	O
extended	O
the	O
address	O
by	O
four	O
address	O
lines	O
to	O
20	O
address	O
lines	O
to	O
allow	O
up	O
to	O
a	O
megabyte	O
of	O
memory	O
in	O
a	O
system	O
.	O
</s>
<s>
Boards	O
for	O
the	O
SS-50	B-Architecture
bus	I-Architecture
were	O
typically	O
9inches	O
wide	O
and	O
5.5inches	O
high	O
.	O
</s>
<s>
The	O
board	O
had	O
Molex	O
0.156inch	O
connectors	O
while	O
the	O
motherboard	B-Device
had	O
the	O
pins	O
.	O
</s>
<s>
The	O
SS-30	O
I/O	B-General_Concept
Bus	I-General_Concept
had	O
the	O
address	O
decoding	O
on	O
the	O
motherboard	B-Device
.	O
</s>
<s>
Each	O
slot	O
was	O
allocated	O
4	O
address	O
(	O
the	O
later	O
MC6809	B-Device
version	O
upped	O
this	O
to	O
16	O
address	O
.	O
)	O
</s>
<s>
Cards	O
designed	O
using	O
the	O
SS-30	O
bus	O
often	O
had	O
their	O
external	O
connectors	O
mounted	O
such	O
that	O
they	O
were	O
accessible	O
outside	O
the	O
computer	O
chassis	O
when	O
installed	O
in	O
SWTPC	O
motherboards	B-Device
.	O
</s>
