HP 8340B Manual 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