<s>
The	O
Parallel	B-Device
Bus	I-Device
Interface	I-Device
,	O
or	O
PBI	O
,	O
is	O
a	O
50-pin	O
port	O
found	O
on	O
some	O
Atari	B-Device
8-bit	I-Device
XL	O
computers	O
.	O
</s>
<s>
It	O
provides	O
unbuffered	O
,	O
direct	O
connection	O
to	O
the	O
system	O
bus	O
lines	O
(	O
address	O
,	O
data	O
,	O
control	O
)	O
,	O
running	O
at	O
the	O
same	O
speed	O
as	O
the	O
6502	B-General_Concept
CPU	O
.	O
</s>
<s>
The	O
600XL	B-Device
and	O
800XL	B-Device
computers	O
,	O
along	O
with	O
the	O
unreleased	O
1400XL	O
and	O
1450XLD	O
had	O
a	O
PBI	O
interface	O
.	O
</s>
<s>
The	O
Enhanced	B-Device
Cartridge	I-Device
Interface	I-Device
,	O
or	O
ECI	O
,	O
was	O
a	O
modified	O
version	O
of	O
the	O
PBI	O
designed	O
to	O
be	O
smaller	O
and	O
less	O
expensive	O
to	O
implement	O
.	O
</s>
<s>
Many	O
of	O
the	O
pins	O
in	O
the	O
PBI	O
were	O
duplicated	O
in	O
the	O
30-pin	O
cartridge	B-Protocol
slot	O
,	O
so	O
ECI	O
was	O
limited	O
to	O
only	O
those	O
14	O
pins	O
in	O
the	O
PBI	O
that	O
were	O
not	O
in	O
the	O
cartridge	B-Protocol
slot	O
.	O
</s>
<s>
The	O
ECI	O
was	O
found	O
on	O
the	O
65XE	B-Device
(	O
late	O
production	O
units	O
only	O
)	O
,	O
the	O
130XE	B-Device
and	O
the	O
800XE	B-Device
.	O
</s>
<s>
As	O
many	O
of	O
these	O
pins	O
were	O
already	O
implemented	O
as	O
part	O
of	O
the	O
already-existing	O
30-pin	O
ROM	B-Protocol
cartridge	I-Protocol
slots	O
on	O
Atari	O
machines	O
,	O
the	O
XE	O
series	O
re-implemented	O
the	O
PBI	O
to	O
include	O
only	O
those	O
pins	O
that	O
the	O
PBI	O
had	O
but	O
the	O
cartridge	B-Protocol
slot	O
did	O
n't	O
.	O
</s>
<s>
The	O
ECI	O
slot	O
was	O
placed	O
beside	O
the	O
cartridge	B-Protocol
slot	O
,	O
allowing	O
a	O
single	O
connector	O
to	O
be	O
inserted	O
into	O
both	O
connectors	O
and	O
re-create	O
the	O
functionality	O
of	O
the	O
entire	O
PBI	O
.	O
</s>
<s>
Atari	O
1064	O
Memory	O
Module	O
-	O
Designed	O
specifically	O
for	O
the	O
600XL	B-Device
,	O
it	O
upgraded	O
the	O
memory	O
of	O
the	O
600XL	B-Device
to	O
64kB	O
.	O
</s>
<s>
Featured	O
a	O
RAMdisk	B-Application
,	O
parallel	O
port	O
,	O
serial	O
port	O
,	O
print	B-Device
spooler	I-Device
and	O
a	O
hard	O
disk	O
interface	O
.	O
</s>
