Mainframe
Description
A
mainframe
is
a
device
into
which
plug-in
modules
may
be
installed
to
create
an
instrument
in
the
modular
measurement
system.
The
HP
70001A
mainframe
provides
the
structural
environment
for
plug-in
instrument
modules
along
with
cooling,
power
,
and
digital
communication
interface
buses
.
It
can
accommodate
1/8-,
1/4-,
3/8-,
and
1/2-width
modules
,
and
has
a
maximum
capacity
of
eight
1/8-width
modules
.
Standard
rack
compatibility
is
provided,
and
bench-top
use
is
facilitated
with
integral
bails
and
retracting
handles
.
The
Hewlett-P
ackard
Modular
System
Interface
Bus
(MSIB)
supports
high-speed
digital
communication
among
instrument
modules
within
a
mainframe
and
among
instruments
connected
to
the
external
MSIB
loop
.
Every
module
in
a
mainframe
has
access
to
the
standard
Hewlett-P
ackard
Interface
Bus
(HP-IB).
This
bus
provides
a
path
of
communication
among
controllers
,
other
HP-IB
instruments
and
individual
modules
.
The
ac
power
input
is
switchable
between
several
ranges
.
90-132
V
ac
,
47|66
Hz
199-264
V
ac
,
47|66
Hz
103-132
V
ac
,
356|444
Hz
(with
Option
400)
The
mainframe
power
supply
processes
the
ac
line
power
to
produces
regulated
40
kHz
ac
power
for
the
modules
,
5
Vdc
for
the
MSIB
,
dc
power
for
the
cooling
fans
and
a
TTL
compatible
line
syncronization
signal.
The
primary
power
output,
24.3
V
ac
(average
voltage
,
not
rms)
at
40
kHz,
provides
up
to
200
W
atts
of
power
.
Two
fans
provide
cooling
for
both
the
mainframe
and
up
to
eight
installed
1/8-width
modules
.
The
cooling
fans
operate
at
variable
speeds:
they
are
slow
at
temperatures
below
30
C,
increasing
their
speed
linearly
above
30
C
to
a
maximum
speed
for
temperatures
above
55
C.
This
provides
adequate
cooling
over
the
permitted
range
of
temperatures
.
Mainframes
with
serial
numbers
2704A01796
and
lower
may
have
single
speed
fans
.
A
F
an
Speed
modication
kit
can
be
ordered
for
these
units
.
This
modication
will
provide
variable
speed
fans
,
reducing
fan
noise
about
3
dB
at
ambient
temperatures
below
30
C.
1-2
General
Information