Agilent Technologies HP 8719D Service Manual page 336

Main CPU @rmware revisions 6.xx and below)
The main CPU is a 16-bit microprocessor that maintains digital control over the
entire instrument through the instrument bus. The main CPU receives external
control information from the front panel or HP-IB, and performs processing
and formatting operations on the raw data in the main RAM. It controls the
digital signal processor, the front panel processor, the display processor, and
the interconnect port interfaces. In addition, when the analyzer is in the
system controller mode, the main CPU controls peripheral devices through the
peripheral port interfaces.
The main CPU has a dedicated EPROM that contains the operating system
for instrument control. Front panel settings are stored in CMOS RAM, with a
battery providing at least 5 years of backup storage when external power is off.
Main CPU (fkrmware revisions 7.xx and above)
The main CPU is a 32-bit microprocessor that maintains digital control over the
entire instrument through the instrument bus. The main CPU receives external
control information from the front panel or HP-IB, and performs processing
and formatting operations on the raw data in the main RAM. It controls the
digital signal processor, the front panel processor, the display processor, and
the interconnect port interfaces. In addition, when the analyzer is in the
system controller mode, the main CPU controls peripheral devices through the
peripheral port interfaces.
The main CPU has a dedicated flash ROM that contains the operating system for
instrument control. Front panel settings are stored in SRAM, with a battery
providing at least 5 years of backup storage when external power is off.
Main RAM
The main RAM (random access memory) is shared memory for the CPU and the
digital signal processor. It stores the raw data received from the digital signal
processor, while additional calculations are performed on it by the CPU. The
CPU reads the resulting formatted data from the main RAM and converts it to
GSP commands It writes these commands to the GSP for output to the analyzer
display.
EEPROM
EEPROM (electricalIy-erasable
factory set correction constants unique to each instrument. These constants
correct for hardware variations to maintain the highest measurement accuracy.
programmable read only memory) contains
Theory of Operation