<s>
The	O
SGI	B-Application
Indigo2	I-Application
(	O
stylized	O
as	O
"	O
Indigo2	O
"	O
)	O
and	O
the	O
SGI	B-Application
Challenge	I-Application
M	I-Application
are	O
Unix	B-Device
workstations	I-Device
which	O
were	O
designed	O
and	O
sold	O
by	O
SGI	O
from	O
1992	O
to	O
1997	O
.	O
</s>
<s>
The	O
Indigo2	O
,	O
codenamed	O
"	O
Fullhouse	O
"	O
,	O
is	O
a	O
desktop	O
workstation	B-Device
.	O
</s>
<s>
The	O
Challenge	O
M	O
is	O
a	O
server	B-Application
which	O
differs	O
from	O
the	O
Indigo2	O
only	O
by	O
a	O
slightly	O
differently	O
colored	O
and	O
badged	O
case	O
,	O
and	O
the	O
absence	O
of	O
graphics	O
and	O
sound	O
hardware	O
.	O
</s>
<s>
Both	O
systems	O
are	O
based	O
on	O
the	O
MIPS	B-Device
processors	O
,	O
with	O
EISA	B-Device
bus	I-Device
and	O
SGI	O
proprietary	O
GIO64	B-Architecture
expansion	O
bus	O
via	O
a	O
riser	O
card	O
.	O
</s>
<s>
The	O
Indigo	B-Device
preceded	O
the	O
Indigo2	O
,	O
which	O
is	O
succeeded	O
by	O
the	O
Octane	B-Device
.	O
</s>
<s>
Indigo2	O
desktop	O
workstations	B-Device
have	O
two	O
models	O
:	O
the	O
teal	O
Indigo2	O
and	O
the	O
purple	O
IMPACT	O
.	O
</s>
<s>
The	O
CPU	B-Device
types	O
,	O
the	O
amount	O
of	O
RAM	O
,	O
and	O
graphics	O
capabilities	O
,	O
depend	O
on	O
the	O
model	O
or	O
sub-model	O
variation	O
.	O
</s>
<s>
Power	O
Indigo2	O
is	O
a	O
version	O
of	O
the	O
teal	O
Indigo2	O
,	O
with	O
the	O
R8000	B-General_Concept
chipset	O
and	O
strong	O
floating-point	B-Algorithm
arithmetic	I-Algorithm
performance	O
.	O
</s>
<s>
The	O
later	O
IMPACT	O
Indigo2	O
workstation	B-Device
model	O
has	O
more	O
computational	O
and	O
visualization	O
power	O
,	O
especially	O
due	O
to	O
the	O
introduction	O
of	O
the	O
R10000	B-General_Concept
series	O
RISC	B-Architecture
CPU	B-Device
and	O
IMPACT	O
graphics	O
.	O
</s>
<s>
All	O
Indigo2	O
models	O
use	O
one	O
of	O
four	O
distinct	O
MIPS	B-Device
CPU	B-Device
variants	O
:	O
the	O
100	O
to	O
250MHz	O
MIPS	B-General_Concept
R4000	I-General_Concept
and	O
R4400	B-General_Concept
,	O
and	O
the	O
Quantum	O
Effect	O
Devices	O
R4600	O
(	O
IP22	O
mainboard	O
)	O
;	O
the	O
75MHz	O
MIPS	B-Device
R8000	B-General_Concept
(	O
IP26	O
mainboard	O
)	O
;	O
and	O
the	O
175	O
to	O
195MHz	O
R10000	B-General_Concept
(	O
IP28	O
mainboard	O
)	O
,	O
which	O
are	O
featured	O
in	O
the	O
last	O
produced	O
Indigo2	O
model	O
,	O
the	O
IMPACT10000	O
.	O
</s>
<s>
All	O
Indigo2	O
motherboards	O
have	O
12	O
SIMM	B-General_Concept
slots	O
,	O
for	O
standard	O
36-bit	O
parity	O
72-pin	O
fast	O
page	O
mode	O
SIMM	B-General_Concept
memory	O
modules	O
seated	O
in	O
groups	O
of	O
four	O
.	O
</s>
<s>
The	O
design	O
of	O
the	O
memory	O
control	O
logic	O
in	O
R10000	B-General_Concept
machines	O
support	O
up	O
to	O
1	O
GB	O
RAM	O
,	O
but	O
the	O
thermal	O
output	O
of	O
older	O
generation	O
of	O
DRAM	O
chips	O
necessitate	O
the	O
512	O
MB	O
limit	O
.	O
</s>
<s>
10Mbit	O
on-board	O
LAN	O
interface	O
,	O
100Mbit	O
LAN	O
options	O
were	O
made	O
by	O
third	O
parties	O
,	O
either	O
via	O
EISA	B-Device
or	O
GIO64	B-Architecture
expansion	O
cards	O
.	O
</s>
<s>
The	O
two	O
most	O
known	O
and	O
widely	O
used	O
Indigo2	O
network	O
cards	O
are	O
the	O
3Com	O
3C597-TX	O
100Mbit	O
EISA	B-Device
,	O
and	O
the	O
Phobos	O
G160	O
GIO64	B-Architecture
.	O
</s>
<s>
The	O
second	O
one	O
offers	O
better	O
overall	O
performance	O
due	O
to	O
using	O
the	O
superior	O
GIO64	B-Architecture
bus	O
,	O
which	O
also	O
has	O
the	O
effect	O
of	O
reducing	O
the	O
CPU	B-Device
utilization	O
due	O
to	O
DMA	B-General_Concept
transfers	O
.	O
</s>
<s>
Pre-IMPACT	O
options	O
consist	O
of	O
the	O
following	O
options	O
:	O
Indigo2	O
XL24	O
,	O
Indigo2	O
XZ	O
,	O
Elan	B-General_Concept
,	O
and	O
Extreme	B-General_Concept
.	O
</s>
<s>
These	O
options	O
are	O
based	O
on	O
the	O
same	O
Express	O
Graphics	O
architecture	O
from	O
the	O
original	O
SGI	B-Device
Indigo	I-Device
,	O
but	O
feature	O
improved	O
performance	O
.	O
</s>
<s>
Physically	O
,	O
they	O
appear	O
to	O
be	O
similar	O
to	O
the	O
older	O
graphics	O
options	O
;	O
the	O
low-end	O
Solid	O
IMPACT	O
board	O
takes	O
up	O
a	O
single	O
GIO-64	O
slot	O
,	O
the	O
mid-range	O
High	O
IMPACT	O
takes	O
up	O
two	O
GIO-64	O
slots	O
,	O
and	O
the	O
high	O
end	O
Maximum	O
IMPACT	O
occupies	O
three	O
.	O
</s>
<s>
A	O
Maximum	O
IMPACT	O
with	O
4	O
MB	O
of	O
texture	O
memory	O
and	O
the	O
correct	O
graphics	O
settings	O
can	O
play	O
the	O
first	O
three	O
of	O
the	O
Quake	B-Application
video	O
game	O
series	O
with	O
acceptable	O
frame	O
rates	O
.	O
</s>
<s>
All	O
graphics	O
options	O
for	O
Indigo2	O
use	O
the	O
standard	O
13W3	B-Protocol
connector	I-Protocol
for	O
connecting	O
the	O
monitor	O
and	O
another	O
connector	O
for	O
3D	O
stereoscopic	B-Algorithm
glasses	O
.	O
</s>
<s>
Although	O
there	O
are	O
four	O
GIO-64	O
slots	O
available	O
and	O
the	O
High	O
IMPACT	O
takes	O
up	O
two	O
,	O
it	O
is	O
not	O
possible	O
to	O
have	O
a	O
High/High	O
configuration	O
.	O
</s>
<s>
The	O
IMPACT	O
boards	O
draw	O
more	O
power	O
than	O
the	O
GIO-64	O
bus	O
can	O
deliver	O
,	O
so	O
IMPACT-ready	O
systems	O
have	O
additional	O
power	O
connectors	O
on	O
the	O
expansion	O
riser	O
card	O
,	O
with	O
a	O
separate	O
connection	O
to	O
the	O
power	O
supply	O
.	O
</s>
<s>
An	O
IMPACT-ready	O
Indigo2	O
must	O
have	O
an	O
IMPACT-ready	O
riser	O
card	O
,	O
an	O
IMPACT-ready	O
power	O
supply	O
,	O
and	O
a	O
sufficiently	O
recent	O
PROM	B-General_Concept
revision	O
.	O
</s>
<s>
The	O
Indigo2	O
's	O
successor	O
,	O
the	O
SGI	B-Device
Octane	I-Device
,	O
has	O
an	O
upgraded	O
XIO	O
bus	O
and	O
the	O
same	O
graphics	O
options	O
in	O
repackaged	O
form	O
.	O
</s>
