<s>
The	O
RA90	B-Device
disk	O
drive	O
was	O
the	O
first	O
Digital	O
Equipment	O
Corporation	O
drive	O
to	O
be	O
based	O
on	O
"	O
thin	O
film	O
"	O
technology	O
.	O
</s>
<s>
Prior	O
to	O
the	O
RA90	B-Device
all	O
Digital	O
disk	O
drives	O
used	O
"	O
oxide	O
"	O
disks	O
,	O
which	O
were	O
an	O
aluminum	O
disk	O
coated	O
with	O
a	O
polyurethane	O
binder	O
resin	O
containing	O
gamma	O
ferric	O
oxide	O
particles	O
as	O
the	O
recording	O
medium	O
.	O
</s>
<s>
The	O
1988-released	O
RA90	B-Device
,	O
which	O
held	O
1.2GB	O
,	O
was	O
used	O
with	O
controllers	O
implementing	O
the	O
Mass	B-Device
Storage	I-Device
Control	I-Device
Protocol	I-Device
.	O
</s>
<s>
The	O
RA90	B-Device
disk	O
drive	O
,	O
in	O
addition	O
to	O
being	O
DEC	O
's	O
first	O
step	O
into	O
thin	O
film	O
technology	O
,	O
also	O
introduced	O
another	O
first	O
for	O
DEC	O
"	O
:	O
Storage	O
Arrays	O
.	O
</s>
<s>
Other	O
models	O
were	O
the	O
SA550	O
and	O
SA650	O
Mixed	O
Storage	O
Arrays	O
,	O
combining	O
RA70s	O
with	O
RA82s	O
(	O
SA550	O
)	O
or	O
RA90s	B-Device
(	O
SA650	O
)	O
.	O
</s>
<s>
The	O
SA482	O
used	O
just	O
RA82s	O
instead	O
of	O
RA90s	B-Device
.	O
</s>
<s>
Replacing	O
the	O
1.2GB	O
RA90s	B-Device
with	O
1.5GB	O
RA92s	O
,	O
an	O
SA800	O
Storage	O
Array	O
held	O
12GB	O
.	O
</s>
<s>
It	O
took	O
Digital	O
a	O
long	O
time	O
to	O
achieve	O
adequate	O
MTBF	O
(	O
mean	O
time	O
before	O
failure	O
)	O
performance	O
standards	O
for	O
the	O
RA-90	B-Device
,	O
which	O
delayed	O
its	O
time	O
to	O
market	O
sufficiently	O
to	O
be	O
undersold	O
by	O
competitors	O
,	O
who	O
,	O
by	O
then	O
,	O
had	O
introduced	O
smaller	O
form	O
factors	O
(	O
smaller	O
disks	O
)	O
at	O
higher	O
capacities	O
and	O
greater	O
reliability	O
.	O
</s>
<s>
RA-90	B-Device
drives	O
were	O
built	O
at	O
Digital	O
's	O
1	O
million	O
square	O
foot	O
(	O
93,000	O
m²	O
)	O
facility	O
in	O
Colorado	O
Springs	O
and	O
the	O
disks	O
were	O
made	O
in	O
Tempe	O
,	O
Arizona	O
.	O
</s>
