<s>
The	O
Rockwell	B-General_Concept
PPS-4	I-General_Concept
,	O
short	O
for	O
"	O
Parallel	O
Processing	O
System	O
,	O
4-bit	O
"	O
,	O
was	O
an	O
early	O
4-bit	O
microprocessor	B-Architecture
from	O
Rockwell	O
International	O
,	O
released	O
in	O
late	O
1972	O
.	O
</s>
<s>
The	O
PPS-4	O
was	O
built	O
on	O
a	O
metal	B-Algorithm
gate	I-Algorithm
process	O
,	O
compared	O
to	O
the	O
contemporary	O
Intel	B-General_Concept
4004	I-General_Concept
which	O
was	O
based	O
on	O
the	O
more	O
advanced	O
silicon	O
gate	O
PMOS	B-Algorithm
logic	I-Algorithm
process	O
.	O
</s>
<s>
This	O
required	O
large	O
amounts	O
of	O
power	O
;	O
it	O
ran	O
on	O
a	O
-17VDC	O
power	O
supply	O
while	O
running	O
at	O
only	O
256kHz	O
,	O
whereas	O
the	O
4004	B-General_Concept
ran	O
at	O
750kHz	O
on	O
a	O
15VDC	O
supply	O
.	O
</s>
<s>
The	O
CPU	O
,	O
part	O
number	O
10660	O
,	O
was	O
packaged	O
in	O
a	O
42-pin	O
quad	B-Algorithm
in-line	I-Algorithm
package	I-Algorithm
.	O
</s>
<s>
The	O
pins	O
included	O
a	O
12-pin	O
address	B-Architecture
bus	I-Architecture
,	O
8-pin	O
data	B-General_Concept
bus	I-General_Concept
and	O
three	O
4-pin	O
input/output	B-General_Concept
ports	O
that	O
could	O
be	O
combined	O
in	O
different	O
ways	O
.	O
</s>
<s>
In	O
contrast	O
,	O
the	O
16-pin	O
4004	B-General_Concept
had	O
4-bit	O
data	O
and	O
address	O
buses	O
,	O
meaning	O
specifying	O
a	O
12-bit	O
address	O
required	O
external	O
latches	B-General_Concept
and	O
several	O
cycles	O
to	O
specify	O
the	O
address	O
and	O
then	O
read	O
an	O
instruction	O
.	O
</s>
<s>
This	O
meant	O
the	O
PPS-4	O
performed	O
at	O
roughly	O
the	O
same	O
overall	O
speed	O
as	O
the	O
4004	B-General_Concept
in	O
spite	O
of	O
running	O
at	O
the	O
clock	O
speed	O
.	O
</s>
<s>
A	O
complete	O
system	O
used	O
the	O
10660	O
CPU	O
,	O
the	O
10706	O
clock	O
generator	O
in	O
a	O
10-pin	O
TO-5	B-Algorithm
package	O
,	O
and	O
one	O
of	O
a	O
variety	O
of	O
ROM	O
or	O
RAM	O
chips	O
.	O
</s>
<s>
The	O
PPS-4/1	O
followed	O
in	O
early	O
1976	O
,	O
moving	O
at	O
last	O
to	O
a	O
PMOS	O
process	O
,	O
while	O
most	O
other	O
companies	O
had	O
since	O
moved	O
to	O
the	O
new	O
NMOS	B-Algorithm
logic	I-Algorithm
.	O
</s>
<s>
A	O
wide	O
variety	O
of	O
PPS-4/1	O
models	O
were	O
produced	O
,	O
with	O
different	O
amounts	O
of	O
RAM	O
,	O
ROM	O
and	O
I/O	B-General_Concept
ports	O
build	O
into	O
the	O
die	O
.	O
</s>
