HP (Hewlett-Packard) C3917A Printer User Manual


 
Memory Management
The printer uses several different types of memory. This memory
can be divided into two different categories, Read Only Memory
(ROM) and Random Access Memory (RAM). ROM memory
consists of the memory located on the Formatter PCA and any
font cartridges that may be installed in the printer. RAM memory
consists of RAM memory resident on the Formatter PCA, SIMM
memory installed in the printer, and the Non-Volatile Memory
(NVRAM) located on the Formatter PCA.
In general, the ROM is responsible for storing the instructions for
the operation of the processor and font information. The RAM
memory is used to store temporary information that will be used
by the printer for a particular print job or a series of print jobs.
This could consist of soft fonts, macros or graphics patterns. RAM
memory is also used by the printer to store data that is being
processed into the raster image that will control the laser and
create the printed page.
The NVRAM is used to store printer configuration information
that can be input from the printer front panel. This information
stored in NVRAM will remain resident in the printer even if the
power to the printer is turned off.
Data Processing
The formatter CPU is responsible for the overall control of all
functions related to the formatter. One of the CPUs main
functions is to maintain communication with the print engine.
This is done by the print engine interface and the DC Controller
PCA. The DC Controller PCA monitors all print engine functions
such as fuser temperature and paper jam status. The print engine
status is communicated by the DC Controller to the formatter
CPU by the print engine interface. The CPU also controls the
process that converts ASCII data received from the host into the
raster data. This raster data is sent to the laser scanner assembly
via the DC Controller.
Finally the CPU comunicates printer status to the user through
the control panel via the front panel interface. The front panel
interface also transmits front panel inputs to the CPU.
5-14 Functional Overview