<s>
DECsystem	B-Device
was	O
a	O
line	O
of	O
server	B-Application
computers	I-Application
from	O
Digital	O
Equipment	O
Corporation	O
.	O
</s>
<s>
They	O
were	O
based	O
on	O
MIPS	B-Device
architecture	I-Device
processors	O
and	O
ran	O
DEC	O
's	O
version	O
of	O
the	O
UNIX	B-Application
operating	I-Application
system	I-Application
,	O
called	O
ULTRIX	B-Operating_System
.	O
</s>
<s>
The	O
DECSYSTEM	B-Device
name	O
was	O
also	O
used	O
for	O
later	O
models	O
of	O
the	O
PDP-10	B-Device
,	O
namely	O
the	O
DECSYSTEM-10	B-Device
and	O
DECSYSTEM-20	B-Device
series	O
.	O
</s>
<s>
Identical	O
to	O
the	O
DECstation	B-Device
3100	I-Device
,	O
but	O
was	O
intended	O
to	O
be	O
used	O
as	O
a	O
multiuser	O
system	O
.	O
</s>
<s>
Rebranded	O
Personal	O
DECstation	B-Device
5000	O
Series	O
without	O
any	O
graphics	O
.	O
</s>
<s>
Rebranded	O
DECstation	B-Device
5000	O
Model	O
100	O
Series	O
without	O
any	O
graphics	O
.	O
</s>
<s>
Rebranded	O
DECstation	B-Device
5000	O
Model	O
200	O
Series	O
without	O
any	O
graphics	O
.	O
</s>
<s>
It	O
replaced	O
the	O
DECsystem	B-Device
3100	O
.	O
</s>
<s>
A	O
pedestal	O
uniprocessor	O
system	O
based	O
on	O
the	O
Q-Bus	B-Architecture
.	O
</s>
<s>
It	O
shared	O
many	O
hardware	O
options	O
with	O
the	O
3x00-series	O
MAYFAIR	O
VAXes	O
,	O
including	O
TK70	O
tape	O
drive	O
,	O
MS650-BA	O
memory	O
and	O
DSSI	B-Architecture
disk	O
drives	O
.	O
</s>
<s>
A	O
pedestal	O
uniprocessor	O
system	O
based	O
on	O
the	O
Q-Bus	B-Architecture
.	O
</s>
<s>
It	O
replaced	O
the	O
DECsystem	B-Device
5400	O
.	O
</s>
<s>
The	O
5500	O
came	O
with	O
native	O
SCSI	O
support	O
,	O
as	O
well	O
as	O
support	O
for	O
DSSI	B-Architecture
disk	O
drives	O
.	O
</s>
<s>
The	O
DECsystem	B-Device
5500	O
is	O
shipped	O
in	O
a	O
BA430	O
enclosure	O
,	O
which	O
provides	O
a	O
12-slot	O
backplane	O
and	O
room	O
for	O
four	O
mass	O
storage	O
devices	O
.	O
</s>
<s>
The	O
DECsystem	B-Device
5800	O
Series	O
are	O
high-end	O
multiprocessor	B-Operating_System
systems	O
.	O
</s>
<s>
The	O
series	O
comprised	O
the	O
DECsystem	B-Device
5810	O
,	O
5820	O
,	O
5830	O
,	O
and	O
5840	O
,	O
with	O
the	O
third	O
digit	O
referring	O
to	O
the	O
number	O
of	O
processors	O
.	O
</s>
<s>
These	O
systems	O
can	O
be	O
considered	O
to	O
be	O
the	O
MIPS/RISC	O
alternatives	O
of	O
the	O
VAX	B-Device
6000	I-Device
operating	O
the	O
XMI	O
and	O
BI	O
bus	O
.	O
</s>
<s>
The	O
DECsystem	B-Device
5900	O
and	O
DECsystem	B-Device
5900/260	O
are	O
rack-mounted	B-Application
DECstation	B-Device
5000	O
Model	O
240	O
and	O
DECstation	B-Device
Model	O
260	O
workstations	O
,	O
respectively	O
,	O
positioned	O
as	O
mid-range	O
servers	O
by	O
Digital	O
.	O
</s>
<s>
The	O
DECsystem	B-Device
5900	O
was	O
introduced	O
in	O
early	O
December	O
1991	O
.	O
</s>
<s>
Their	O
intended	O
replacement	O
was	O
the	O
DEC	B-Device
3000	I-Device
Model	I-Device
800S	I-Device
AXP	I-Device
packaged	O
in	O
a	O
similar	O
rack-mountable	B-Application
enclosure	O
.	O
</s>
<s>
The	O
DECstation	B-Device
system	O
module	O
is	O
repackaged	O
in	O
a	O
CPU	O
drawer	O
,	O
which	O
is	O
mounted	O
in	O
a	O
rack	O
with	O
a	O
mounting	O
kit	O
which	O
permits	O
the	O
drawer	O
to	O
be	O
slid	O
in	O
and	O
out	O
.	O
</s>
<s>
However	O
,	O
as	O
the	O
system	O
module	O
that	O
these	O
systems	O
use	O
does	O
not	O
feature	O
multiprocessing	B-Operating_System
capabilities	O
,	O
the	O
presence	O
of	O
two	O
CPU	O
drawers	O
in	O
a	O
rack	O
simply	O
meant	O
that	O
there	O
were	O
two	O
separate	O
systems	O
.	O
</s>
<s>
The	O
H9A00	O
enclosure	O
,	O
a	O
19-inch	B-Application
rack	I-Application
,	O
contains	O
a	O
minimum	O
of	O
one	O
CPU	O
drawer	O
and	O
one	O
mass	O
storage	O
drawer	O
.	O
</s>
<s>
The	O
DECsystem	B-Device
5900	O
has	O
a	O
width	O
of	O
,	O
a	O
height	O
of	O
,	O
a	O
depth	O
of	O
and	O
a	O
weight	O
of	O
depending	O
on	O
the	O
configuration	O
.	O
</s>
