Specifications

E–3Principles of Operation
Common Controller PCBA
The heart of the LG06 Text and Graphics printer is the common controller
printed circuit board assembly (PCBA), also called the common controller
board (CCB). The CCB oversees and coordinates all printer functions.
The CCB is functionally two units, the data processing unit (DPU) and the
real–time processing unit (RTPU). The DPU converts all character data into
printable dot images. The DPU is the high–level logical controller of the
printer; it is not involved in real–time or hardware–dependent printer
operation. The RTPU operates the host interfaces, operator control panel, and
the print mechanism. The RTPU also monitors the fault circuitry in the
mechanism.
The DPU and RTPU communicate by means of shared memory. The DPU
gets host and operator input from buffers in memory which are filled by the
RTPU, and returns dot images and operator messages to buffers in memory
which the RTPU empties. Figure E–2 broadly summarizes the architecture of
the CCB.
HOST
INTERFACE
OPERATOR
CONTROL
PANEL
PRINTING
MECHANISM
INTERFACE
DATA PROCESSING
SHARED MEMORY
REAL–TIME
CCB
UNIT
PROCESSING
UNIT
Figure E–2. Architectural Overview of the Common Controller Board
(CCB)