<s>
The	O
DF-224	B-General_Concept
is	O
a	O
space-qualified	O
computer	O
used	O
in	O
space	O
missions	O
from	O
the	O
1980s	O
.	O
</s>
<s>
The	O
main	O
memory	O
consisted	O
of	O
six	O
memory	O
units	O
,	O
each	O
with	O
8K	O
24-bit	O
words	O
of	O
plated	B-General_Concept
wire	I-General_Concept
memory	I-General_Concept
,	O
with	O
up	O
to	O
48K	O
words	O
total	O
.	O
</s>
<s>
Four	O
memory	O
modules	O
could	O
be	O
powered	O
up	O
at	O
one	O
time	O
,	O
resulting	O
in	O
a	O
maximum	O
of	O
32K	O
words	O
of	O
available	O
memory	O
,	O
though	O
some	O
applications	O
such	O
as	O
the	O
Hubble	O
Space	O
Telescope	O
used	O
fewer	O
memory	O
banks	O
to	O
allow	O
for	O
graceful	B-General_Concept
failure	I-General_Concept
modes	I-General_Concept
.	O
</s>
<s>
The	O
processor	O
used	O
fixed-point	O
arithmetic	O
with	O
a	O
two	B-General_Concept
's	I-General_Concept
complement	I-General_Concept
format	O
.	O
</s>
<s>
Compared	O
to	O
computers	O
that	O
came	O
later	O
,	O
the	O
DF-224	B-General_Concept
was	O
big	O
and	O
slow	O
.	O
</s>
<s>
The	O
DF-224	B-General_Concept
on	O
HST	O
was	O
augmented	O
with	O
a	O
386	O
co-processor	O
on	O
the	O
first	O
serving	O
mission	O
(	O
SM1	O
)	O
.	O
</s>
<s>
The	O
DF-224	B-General_Concept
was	O
one	O
of	O
the	O
candidate	O
computers	O
for	O
the	O
Space	O
Shuttle	O
,	O
but	O
was	O
not	O
selected	O
.	O
</s>
