HP 8340b User Manual

Controller
Section
Theory
of
Operation
THE
ADDRESS
BUS
AND DATA
BUS
The
instrument
has
a
16-bit
I/O
data
bus
(DB
0-15)
and
a
5-bit
I/O
address
bus
(ADR
0-4)
that
runs
throughout
the
instrument.
The
I/O
data bus
is
bidirectional, sending
and
receiving
data
from various
digital
circuits.
LOW
INSTRUMENT PRESET
(LIPS)
When
you
turn
the
instrument
on,
or
press
[INSTR
PRESET],
LIPS
(low
instrument preset)
is
gener¬
ated.
This
signal
initiates
several events
in
the
controller section:
Overrides
the
A59
assembly's
ability
to
shut
down
the
processor
Disables
access
to
RAM
Resets
the
instrument
processor
and
the display
processor
Activates
all
front
panel
LEDs
Activates
the
16
self
test
LEDs
on
the
A60
assembly
When
LIPS
is
released,
the
instrument controller performs
a
self
test
that:
Checks the
instrument
processor
internal
registers
Partially
checks
RAM
Checks
ROM
Checks
the
I/O
address bus
(ADR
1-5)
Checks
the
I/O
data bus
(DB
0-15)
Verifies
the calibration
data check
sum
(see service
introduction)
Checks the
analog-to-digital
converter
This
circuit,
located
on
the
A27
level
control
assembly,
is
essentially
an
internal
voltmeter
that
allows
the
instrument
processor
to
monitor several
DC
levels
in
the
instrument
(e.g.
modulation
level,
sweep
voltage,
ALC
level).
If
the
self
test
is
initiated
by
an
instrument
preset,
the
instrument sets
all
front
panel
functions to
a
preset condition,
and
is
ready
to
begin
operation.
HIGH
POWER UP
(HPUP)
When
you
turn
the
power
switch
on,
HPUP
remains
low
until
the
power
supplies stabilize,
then
it
goes
high,
resetting
the
instrument
processor
to
restore previous
instrument settings
(stored
in
RAM)
after
self
test
completes.
F-2
Controller
Section
Theory
of
Operation
HP
8340B/41B

HP 8340b Specifications

General

Brand	HP
Model	8340b
Category	Inverter
Language	English