HP 8340b - Page 479

A60
PROCESSOR ASSEMBLY
The
A60
processor
assembly performs
all
instrument
data
processing.
This
assembly
consist
of:
• A
microprocessor
•
Memory
•
An
HP-IB interface
•
The
necessary
circuitry
for:
clock
generation
address
and
memory
decoding
buffering
interrupt
handling
The
microprocessor
interfaces
directly
with
memory,
which
consists
of:
•
32K
words
of
Ultra
Violet
Erasable Programmable
Read
Only
Memory
(UVEPROM)
The
instrument
software program
(firmware)
is
stored
in
this
section
of
memory,
with
the
default
calibration
data.
•
2K
words
of
Electrically Erasable
Programmable
Read
Only
Memory
(EEPROM)
Protected calibration
data
is
stored
here.
•
8K
words
of
Random
Access
Memory
(RAM)
Working
calibration
data and
SAVE/RECALL
register
values
are
stored
here.
Battery
backup
provides
power
to
RAM
when
AC
power
is
disconnected.
If
the
backup
power
fails,
working
calibration
data and
SAVE/RECALL
information
is
lost.
When
AC
power
is
restored,
the
EEPROM
calibration data
is
loaded
in
RAM,
and
the
front
panel
displays
CALIBRATION
RESTORED.
NOTE:
1
word
=
2
bytes;
1
byte
=
8
bits.
The
microprocessor
is
controlled
by
the
firmware stored
in
memory.
With
this
program,
the
micro¬
processor can
transfer data
(I/O
addressing) and
internally
process
data
it
has
accessed.
All
data
transfers
go
through
the
microprocessor.
The
A60
processor assembly
communicates
with
the
rest
of
the
instrument
by
means
of
the
internal
address
and
data
busses.
External
communication
is
through
the
HP-IB
connection
on
the
rear
panel.
The
HP-IB
interface
circuitry
provides
the
link
between
the
internal
instrument
bus and
the
external
HP-IB
interface.
HP
8340B/41B
Controller Section
Theory
of
Operation
F-5/F-6