<s>
The	O
MicroVAX	B-Device
is	O
a	O
discontinued	O
family	O
of	O
low-cost	O
minicomputers	B-Architecture
developed	O
and	O
manufactured	O
by	O
Digital	O
Equipment	O
Corporation	O
(	O
DEC	O
)	O
.	O
</s>
<s>
The	O
first	O
model	O
,	O
the	O
MicroVAX	B-Device
I	O
,	O
was	O
introduced	O
in	O
1983	O
.	O
</s>
<s>
They	O
used	O
processors	O
that	O
implemented	O
the	O
VAX	B-Device
instruction	B-General_Concept
set	I-General_Concept
architecture	I-General_Concept
(	O
ISA	O
)	O
and	O
were	O
succeeded	O
by	O
the	O
VAX	B-Device
4000	I-Device
.	O
</s>
<s>
Many	O
members	O
of	O
the	O
MicroVAX	B-Device
family	O
had	O
corresponding	O
VAXstation	B-Device
variants	O
,	O
which	O
primarily	O
differ	O
by	O
the	O
addition	O
of	O
graphics	O
hardware	O
.	O
</s>
<s>
The	O
MicroVAX	B-Device
family	O
supports	O
Digital	O
's	O
VMS	B-Operating_System
and	O
ULTRIX	B-Operating_System
operating	B-General_Concept
systems	I-General_Concept
.	O
</s>
<s>
Prior	O
to	O
VMS	B-Operating_System
V5.0	O
,	O
MicroVAX	B-Device
hardware	O
required	O
a	O
dedicated	O
version	O
of	O
VMS	B-Operating_System
named	O
MicroVMS	O
.	O
</s>
<s>
The	O
MicroVAX	B-Device
I	O
,	O
code-named	O
Seahorse	O
,	O
introduced	O
in	O
October	O
1984	O
,	O
was	O
one	O
of	O
DEC	O
's	O
first	O
VAX	B-Device
computers	O
to	O
use	O
very-large-scale	O
integration	O
(	O
VLSI	O
)	O
technology	O
.	O
</s>
<s>
The	O
KA610	O
CPU	O
module	O
(	O
also	O
known	O
as	O
the	O
KD32	O
)	O
contained	O
two	O
custom	O
chips	O
which	O
implemented	O
the	O
ALU	B-General_Concept
and	O
FPU	B-General_Concept
while	O
TTL	B-General_Concept
chips	O
were	O
used	O
for	O
everything	O
else	O
.	O
</s>
<s>
Two	O
variants	O
of	O
the	O
floating	O
point	O
chips	O
were	O
supported	O
,	O
with	O
the	O
chips	O
differing	O
by	O
the	O
type	O
of	O
floating	O
point	O
instructions	O
supported	O
,	O
F	O
and	O
G	O
,	O
or	O
F	O
and	O
D	O
.	O
The	O
system	O
was	O
implemented	O
on	O
two	O
quad-height	O
Q-bus	B-Architecture
cards	O
-	O
a	O
Data	O
Path	O
Module	O
(	O
DAP	O
)	O
and	O
Memory	O
Controller	O
(	O
MCT	O
)	O
.	O
</s>
<s>
The	O
MicroVAX	B-Device
I	O
used	O
Q-bus	B-Architecture
memory	O
cards	O
,	O
which	O
limited	O
the	O
maximum	O
memory	O
to	O
4MiB	O
.	O
</s>
<s>
The	O
performance	O
of	O
the	O
MicroVAX	B-Device
I	O
was	O
rated	O
at	O
0.3	O
VUPs	O
,	O
equivalent	O
to	O
the	O
earlier	O
VAX-11/730	O
.	O
</s>
<s>
The	O
MicroVAX	B-Device
II	O
,	O
code-named	O
Mayflower	O
,	O
was	O
a	O
mid-range	O
MicroVAX	B-Device
introduced	O
in	O
May	O
1985	O
and	O
shipped	O
shortly	O
thereafter	O
.	O
</s>
<s>
It	O
ran	O
VAX/VMS	B-Operating_System
or	O
,	O
alternatively	O
,	O
ULTRIX	B-Operating_System
,	O
the	O
DEC	O
native	O
Unix	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
At	O
least	O
one	O
non-DEC	O
operating	B-General_Concept
system	I-General_Concept
was	O
available	O
,	O
BSD	B-Operating_System
Unix	I-Operating_System
from	O
MtXinu	B-Operating_System
.	O
</s>
<s>
It	O
used	O
the	O
KA630-AA	O
CPU	O
module	O
,	O
a	O
quad-height	O
Q22-Bus	B-Architecture
module	O
,	O
which	O
featured	O
a	O
MicroVAX	B-Device
78032	I-Device
microprocessor	O
and	O
a	O
MicroVAX	B-Device
78132	O
floating-point	O
coprocessor	O
operating	O
at	O
5MHz	O
(	O
200	O
ns	O
cycle	O
time	O
)	O
.	O
</s>
<s>
Two	O
gate	O
arrays	O
on	O
the	O
module	O
implemented	O
the	O
external	O
interface	O
for	O
the	O
microprocessor	O
,	O
Q22-bus	B-Architecture
interface	O
and	O
the	O
scatter-gather	O
map	O
for	O
DMA	O
transfers	O
over	O
the	O
Q22-Bus	B-Architecture
.	O
</s>
<s>
The	O
MicroVAX	B-Device
II	O
supported	O
1	O
to	O
16	O
MB	O
of	O
memory	O
through	O
zero	O
,	O
one	O
or	O
two	O
memory	O
expansion	O
modules	O
.	O
</s>
<s>
The	O
MicroVAX	B-Device
II	O
came	O
in	O
three	O
models	O
of	O
enclosure	O
:	O
</s>
<s>
KA620	O
referred	O
to	O
a	O
single-board	B-Device
MicroVAX	B-Device
II	O
designed	O
for	O
automatic	O
test	O
equipment	O
and	O
manufacturing	O
applications	O
which	O
only	O
ran	O
DEC	O
's	O
real-time	O
VAXELN	B-Operating_System
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
A	O
KA620	O
with	O
1	O
MB	O
of	O
memory	O
bundled	O
with	O
the	O
VAXELN	B-Operating_System
Run-Time	O
Package	O
2.3	O
was	O
priced	O
at	O
US$	O
5,000	O
.	O
</s>
<s>
Mira	O
referred	O
to	O
a	O
fault-tolerant	O
configuration	O
of	O
the	O
MicroVAX	B-Device
II	O
developed	O
by	O
DEC	O
's	O
European	O
Centre	O
for	O
Special	O
Systems	O
located	O
in	O
Annecy	O
in	O
France	O
.	O
</s>
<s>
The	O
system	O
consisted	O
of	O
two	O
MicroVAX	B-Device
78032	I-Device
microprocessors	O
,	O
an	O
active	O
and	O
standby	O
microprocessor	O
in	O
a	O
single	O
box	O
,	O
connected	O
by	O
Ethernet	O
and	O
controlled	O
by	O
a	O
software	O
switch	O
.	O
</s>
<s>
A	O
MicroVAX	B-Device
II	O
in	O
BA213	O
enclosure	O
.	O
</s>
<s>
BA23	O
-	O
or	O
BA123-enclosure	O
MicroVAX	B-Device
upgraded	O
with	O
KA650	O
CPU	O
module	O
containing	O
a	O
CVAX	B-Device
chip	O
set	O
.	O
</s>
<s>
BA23	O
-	O
or	O
BA123-enclosure	O
MicroVAX	B-Device
upgraded	O
with	O
KA655	O
CPU	O
module	O
.	O
</s>
<s>
BA23	O
-	O
or	O
BA123-enclosure	O
MicroVAX	B-Device
upgraded	O
with	O
KA660	O
CPU	O
module	O
.	O
</s>
<s>
The	O
MicroVAX	B-Device
2000	O
,	O
code-named	O
TeamMate	O
,	O
was	O
a	O
low-cost	O
MicroVAX	B-Device
introduced	O
on	O
10	O
February	O
1987	O
.	O
</s>
<s>
In	O
January	O
1987	O
,	O
the	O
MicroVAX	B-Device
2000	O
was	O
the	O
first	O
VAX	B-Device
system	O
targeted	O
at	O
both	O
universities	O
and	O
VAX	B-Device
programmers	O
who	O
wanted	O
to	O
work	O
from	O
remote	O
locations	O
.	O
</s>
<s>
The	O
MicroVAX	B-Device
2000	O
used	O
the	O
same	O
microprocessor	O
and	O
floating-point	O
coprocessor	O
as	O
the	O
MicroVAX	B-Device
II	O
,	O
but	O
was	O
feature	O
reduced	O
in	O
order	O
to	O
lower	O
the	O
cost	O
.	O
</s>
<s>
Limitations	O
were	O
a	O
reduced	O
maximum	O
memory	O
capacity	O
,	O
14	O
MB	O
versus	O
16	O
MB	O
in	O
MicroVAX	B-Device
II	O
systems	O
and	O
the	O
lack	O
of	O
Q-Bus	B-Architecture
or	O
any	O
expansion	O
bus	O
.	O
</s>
<s>
The	O
system	O
could	O
have	O
a	O
Shugart-based	O
harddrive	O
with	O
ST412	B-Device
interface	O
and	O
MFM	B-Protocol
encoding	I-Protocol
and	O
had	O
a	O
built	O
in	O
5.25-inch	O
floppy	O
drive	O
(	O
named	O
RX33	O
in	O
DEC	O
jargon	O
)	O
for	O
software	O
distribution	O
and	O
backup	O
.	O
</s>
<s>
Supported	O
operating	B-General_Concept
systems	I-General_Concept
were	O
VMS	B-Operating_System
and	O
ULTRIX	B-Operating_System
.	O
</s>
<s>
The	O
MicroVAX	B-Device
3100	O
Series	O
was	O
introduced	O
in	O
1987	O
.	O
</s>
<s>
Processor	O
:	O
KA51	O
,	O
NVAX	B-Device
,	O
83.34	O
MHz	O
(	O
12	O
ns	O
)	O
,	O
512	O
KB	O
external	O
cache	O
.	O
</s>
<s>
KA59	O
,	O
NVAX	B-Device
,	O
100	O
MHz	O
(	O
10	O
ns	O
)	O
,	O
512	O
KB	O
external	O
cache	O
.	O
</s>
<s>
InfoServer	O
100/150/1000	O
General	O
purpose	O
storage	O
server	O
(	O
disk	O
,	O
CD-ROM	O
,	O
tape	O
and	O
MOP	B-Operating_System
boot	O
server	O
)	O
related	O
to	O
MicroVAX	B-Device
3100	O
Model	O
10	O
,	O
running	O
custom	O
firmware	O
,	O
KA41-C	O
CPU	O
.	O
</s>
<s>
The	O
MicroVAX	B-Device
3500	O
and	O
MicroVAX	B-Device
3600	O
,	O
code-named	O
Mayfair	O
,	O
were	O
introduced	O
in	O
September	O
1987	O
and	O
were	O
meant	O
to	O
be	O
the	O
higher	O
end	O
complement	O
of	O
the	O
MicroVAX	B-Device
family	O
.	O
</s>
<s>
These	O
new	O
machines	O
featured	O
more	O
than	O
three	O
times	O
the	O
performance	O
of	O
the	O
MicroVAX	B-Device
II	O
and	O
supported	O
32	O
MB	O
of	O
ECC	O
main	O
memory	O
(	O
twice	O
that	O
of	O
the	O
MicroVAX	B-Device
II	O
)	O
.	O
</s>
<s>
The	O
performance	O
improvements	O
over	O
the	O
MicroVAX	B-Device
II	O
resulted	O
from	O
the	O
increased	O
clock	O
rate	O
of	O
the	O
CVAX	B-Device
chip	O
set	O
,	O
which	O
operated	O
at	O
11.11MHz	O
(	O
90	O
ns	O
cycle	O
time	O
)	O
along	O
with	O
a	O
two-level	O
,	O
write-through	O
caching	O
architecture	O
.	O
</s>
<s>
The	O
MicroVAX	B-Device
3300	O
and	O
MicroVAX	B-Device
3400	O
,	O
code-named	O
Mayfair	O
II	O
,	O
were	O
entry-level	O
to	O
mid-range	O
server	O
computers	O
introduced	O
on	O
19	O
October	O
1988	O
intended	O
to	O
compete	O
with	O
the	O
IBM	B-Device
AS/400	I-Device
.	O
</s>
<s>
The	O
MicroVAX	B-Device
3800	O
and	O
MicroVAX	B-Device
3900	O
,	O
code-named	O
Mayfair	O
III	O
,	O
were	O
introduced	O
in	O
April	O
1989	O
.	O
</s>
<s>
They	O
were	O
high-end	O
models	O
in	O
the	O
MicroVAX	B-Device
family	O
,	O
replacing	O
the	O
MicroVAX	B-Device
3500	O
and	O
MicroVAX	B-Device
3600	O
,	O
and	O
were	O
intended	O
to	O
compete	O
with	O
the	O
IBM	B-Device
AS/400	I-Device
.	O
</s>
<s>
At	O
introduction	O
,	O
the	O
starting	O
price	O
of	O
the	O
MicroVAX	B-Device
3800	O
was	O
US$	O
81,000	O
and	O
that	O
of	O
the	O
MicroVAX	B-Device
3900	O
was	O
US$	O
120,200	O
.	O
</s>
<s>
A	O
variant	O
of	O
the	O
MicroVAX	B-Device
3800	O
,	O
the	O
rtVAX	O
3800	O
,	O
was	O
intended	O
for	O
real-time	B-General_Concept
computing	I-General_Concept
(	O
RTC	O
)	O
applications	O
such	O
as	O
computer-aided	O
manufacturing	O
(	O
CAM	O
)	O
.	O
</s>
<s>
These	O
systems	O
used	O
the	O
KA655	O
CPU	O
module	O
,	O
which	O
contained	O
a	O
16.67MHz	O
(	O
60	O
ns	O
cycle	O
time	O
)	O
CVAX	B-Device
chip	O
set	O
.	O
</s>
