<s>
The	O
VAX	B-Device
4000	I-Device
is	O
a	O
discontinued	O
family	O
of	O
low-end	O
minicomputers	B-Architecture
developed	O
and	O
manufactured	O
by	O
Digital	O
Equipment	O
Corporation	O
(	O
later	O
Compaq	O
)	O
using	O
microprocessors	O
implementing	O
the	O
VAX	B-Device
instruction	B-General_Concept
set	I-General_Concept
architecture	I-General_Concept
(	O
ISA	O
)	O
.	O
</s>
<s>
The	O
VAX	B-Device
4000	I-Device
succeeded	O
the	O
MicroVAX	B-Device
family	O
,	O
and	O
shipped	O
with	O
the	O
OpenVMS	B-Operating_System
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
It	O
was	O
the	O
last	O
family	O
of	O
low-end	O
VAX	B-Device
systems	O
,	O
as	O
the	O
platform	O
was	O
discontinued	O
by	O
Compaq	O
.	O
</s>
<s>
The	O
VAX	B-Device
4000	I-Device
Model	O
300	O
,	O
code-named	O
"	O
Pele	O
"	O
,	O
was	O
introduced	O
on	O
9	O
July	O
1990	O
at	O
DECworld	O
in	O
Boston	O
,	O
Massachusetts	O
,	O
replacing	O
the	O
MicroVAX	B-Device
3800	O
and	O
3900	O
.	O
</s>
<s>
It	O
used	O
the	O
time-sharing	O
KA670-AA	O
CPU	O
module	O
containing	O
a	O
35.71MHz	O
(	O
28	O
ns	O
cycle	O
time	O
)	O
Rigel	B-Device
chip	O
set	O
with	O
a	O
128KB	O
external	O
secondary	O
cache	O
protected	O
by	O
ECC	O
built	O
from	O
84	O
ns	O
SRAM	O
.	O
</s>
<s>
Q-bus	B-Architecture
was	O
used	O
for	O
expansion	O
.	O
</s>
<s>
VAX	B-Device
4000	I-Device
Model	O
200	O
,	O
code-named	O
"	O
Spitfire	O
"	O
,	O
was	O
introduced	O
in	O
January	O
1991	O
as	O
replacement	O
for	O
the	O
MicroVAX	B-Device
3400	O
.	O
</s>
<s>
It	O
was	O
positioned	O
beneath	O
the	O
VAX	B-Device
4000	I-Device
Model	O
300	O
.	O
</s>
<s>
The	O
VAX	B-Device
4000	I-Device
Model	O
500	O
,	O
code-named	O
"	O
Omega/N	O
"	O
,	O
was	O
introduced	O
on	O
30	O
October	O
1991	O
,	O
with	O
availability	O
in	O
December	O
1991	O
.	O
</s>
<s>
It	O
succeeded	O
the	O
VAX	B-Device
4000	I-Device
Model	O
300	O
,	O
but	O
the	O
older	O
system	O
remained	O
available	O
as	O
a	O
lower	O
cost	O
alternative	O
.	O
</s>
<s>
It	O
used	O
the	O
KA680	O
CPU	O
module	O
containing	O
a	O
71.43MHz	O
(	O
14	O
ns	O
cycle	O
time	O
)	O
NVAX	B-Device
microprocessor	O
with	O
128KB	O
of	O
external	O
tertiary	O
cache	O
.	O
</s>
<s>
The	O
VAX	B-Device
4000	I-Device
Model	O
100	O
,	O
code-named	O
"	O
Cheetah-Q	O
"	O
,	O
is	O
an	O
entry-level	O
VAX	B-Device
4000	I-Device
system	O
introduced	O
on	O
7	O
July	O
1992	O
.	O
</s>
<s>
It	O
used	O
the	O
KA52	O
CPU	O
module	O
containing	O
a	O
72MHz	O
(	O
14	O
ns	O
cycle	O
time	O
)	O
NVAX	B-Device
microprocessor	O
with	O
128KB	O
of	O
external	O
tertiary	O
cache	O
.	O
</s>
<s>
The	O
VAX	B-Device
4000	I-Device
Model	O
400	O
,	O
code-named	O
"	O
Slow-mega	O
"	O
,	O
was	O
a	O
distributed	O
server	O
,	O
positioned	O
as	O
a	O
mid-range	O
VAX	B-Device
4000	I-Device
system	O
,	O
introduced	O
on	O
7	O
July	O
1992	O
.	O
</s>
<s>
It	O
used	O
the	O
KA675	O
CPU	O
module	O
containing	O
a	O
63MHz	O
(	O
16	O
ns	O
)	O
NVAX	B-Device
microprocessor	O
with	O
uCode	O
patch	O
changes	O
to	O
slow	O
it	O
down	O
beyond	O
the	O
cycle	O
scaling	O
,	O
with	O
128KB	O
of	O
external	O
tertiary	O
cache	O
.	O
</s>
<s>
The	O
VAX	B-Device
4000	I-Device
Model	O
600	O
,	O
code-named	O
"	O
Omega/N	O
+	O
"	O
,	O
was	O
a	O
distributed	O
server	O
,	O
positioned	O
as	O
a	O
high-end	O
VAX	B-Device
4000	I-Device
system	O
,	O
introduced	O
on	O
7	O
July	O
1992	O
.	O
</s>
<s>
It	O
used	O
the	O
KA690	O
CPU	O
module	O
containing	O
an	O
83MHz	O
(	O
12	O
ns	O
)	O
NVAX	B-Device
microprocessor	O
with	O
and	O
512KB	O
of	O
external	O
tertiary	O
cache	O
.	O
</s>
<s>
The	O
VAX	B-Device
4000	I-Device
Model	O
100A	O
,	O
code-named	O
"	O
Cheetah-Q	O
"	O
,	O
was	O
introduced	O
on	O
12	O
October	O
1993	O
.	O
</s>
<s>
It	O
used	O
the	O
KA52	O
CPU	O
module	O
containing	O
a	O
72MHz	O
(	O
14	O
ns	O
cycle	O
time	O
)	O
NVAX	B-Device
microprocessor	O
with	O
128KB	O
of	O
external	O
tertiary	O
cache	O
.	O
</s>
<s>
The	O
VAX	B-Device
4000	I-Device
Model	O
500A	O
,	O
code-named	O
"	O
Omega/N	O
"	O
,	O
was	O
introduced	O
on	O
12	O
October	O
1993	O
.	O
</s>
<s>
It	O
used	O
the	O
KA681	O
CPU	O
module	O
containing	O
a	O
71.43MHz	O
(	O
14	O
ns	O
cycle	O
time	O
)	O
NVAX	B-Device
microprocessor	O
with	O
128KB	O
of	O
external	O
tertiary	O
cache	O
.	O
</s>
<s>
The	O
VAX	B-Device
4000	I-Device
Model	O
600A	O
,	O
code-named	O
"	O
Omega/N	O
+	O
"	O
,	O
was	O
introduced	O
on	O
12	O
October	O
1993	O
.	O
</s>
<s>
It	O
used	O
the	O
KA691	O
CPU	O
module	O
containing	O
an	O
83MHz	O
(	O
12	O
ns	O
cycle	O
time	O
)	O
NVAX	B-Device
microprocessor	O
with	O
512KB	O
of	O
external	O
tertiary	O
cache	O
.	O
</s>
<s>
The	O
VAX	B-Device
4000	I-Device
Model	O
700A	O
,	O
code-named	O
"	O
Legacy	O
"	O
,	O
was	O
introduced	O
on	O
12	O
October	O
1993	O
.	O
</s>
<s>
It	O
used	O
the	O
KA692	O
CPU	O
module	O
containing	O
a	O
100MHz	O
(	O
10	O
ns	O
cycle	O
time	O
)	O
NVAX	B-Device
microprocessor	O
with	O
2MB	O
of	O
external	O
tertiary	O
cache	O
.	O
</s>
<s>
The	O
VAX	B-Device
4000	I-Device
Model	O
105	O
,	O
code	O
named	O
"	O
Cheetah-Q	O
+	O
"	O
,	O
was	O
introduced	O
on	O
12	O
April	O
1994	O
.	O
</s>
<s>
It	O
used	O
the	O
KA53	O
CPU	O
module	O
containing	O
an	O
83MHz	O
(	O
12	O
ns	O
cycle	O
time	O
)	O
NVAX	B-Device
microprocessor	O
with	O
128KB	O
of	O
external	O
tertiary	O
cache	O
.	O
</s>
<s>
The	O
VAX	B-Device
4000	I-Device
Model	O
505A	O
,	O
code-named	O
"	O
Omega/N	O
+	O
"	O
,	O
was	O
introduced	O
in	O
late	O
August	O
1994	O
.	O
</s>
<s>
It	O
used	O
an	O
83MHz	O
(	O
12	O
ns	O
)	O
NVAX	B-Device
microprocessor	O
with	O
512KB	O
of	O
external	O
tertiary	O
cache	O
.	O
</s>
<s>
The	O
VAX	B-Device
4000	I-Device
Model	O
705A	O
,	O
code-named	O
"	O
Legacy+	O
"	O
,	O
was	O
introduced	O
in	O
late	O
August	O
1994	O
.	O
</s>
<s>
It	O
used	O
the	O
KA694	O
CPU	O
module	O
containing	O
a	O
111.12MHz	O
(	O
9	O
ns	O
cycle	O
time	O
)	O
NVAX	B-Device
microprocessor	O
with	O
2MB	O
of	O
external	O
tertiary	O
cache	O
.	O
</s>
<s>
The	O
VAX	B-Device
4000	I-Device
Model	O
106A	O
,	O
code-named	O
"	O
Cheetah-Q	O
++	O
"	O
,	O
used	O
the	O
KA54	O
CPU	O
module	O
containing	O
a	O
100MHz	O
(	O
10	O
ns	O
cycle	O
time	O
)	O
NVAX	B-Device
microprocessor	O
with	O
512KB	O
of	O
external	O
tertiary	O
cache	O
.	O
</s>
<s>
It	O
was	O
replaced	O
by	O
the	O
VAX	B-Device
4000	I-Device
Model	O
108	O
.	O
</s>
<s>
The	O
VAX	B-Device
4000	I-Device
Model	O
108	O
,	O
code-named	O
"	O
Cheetah-Q	O
++	O
"	O
,	O
was	O
introduced	O
on	O
8	O
October	O
1996	O
to	O
replace	O
the	O
VAX	B-Device
4000	I-Device
Model	O
106A	O
.	O
</s>
<s>
It	O
used	O
the	O
KA57	O
CPU	O
module	O
containing	O
a	O
100MHz	O
(	O
10	O
ns	O
cycle	O
time	O
)	O
NVAX	B-Device
microprocessor	O
with	O
512KB	O
of	O
external	O
tertiary	O
cache	O
.	O
</s>
<s>
The	O
VAX	B-Device
4000	I-Device
Model	O
50	O
,	O
code-named	O
"	O
VAXbrick	O
"	O
,	O
was	O
an	O
upgrade	O
for	O
MicroVAX	B-Device
3x00	I-Device
or	O
VAX	B-Device
4000	I-Device
Model	O
200	O
.	O
</s>
<s>
It	O
used	O
the	O
KA600	O
CPU	O
module	O
containing	O
a	O
NVAX	B-Device
microprocessor	O
.	O
</s>
