Specifications

2–15
Principles of Operation
Mechanical Interface Functions
Three mechanical operations are coordinated in printing: paper motion,
ribbon motion, and shuttle motion. Virtually all digital handling of paper
motion is contained in the RTPU. The ribbon and shuttle are controlled by
logic on the mechanism driver board, under the direction of the RTPU.
Figure 2–12 shows the mechanical interface section of the RTPU.
DATA PROCESSING
RTPU
REAL–TIME PROCESSING UNIT
UNIT
PROCESSOR
UART
DOT PLUCKER
PAPER FEED
EPROM
SHARED MEMORY
Shuttle
and
Ribbon
Paper
Control
CONTROLLER
Control
Figure 2–12. Mechanical Interface Functions of the RTPU
Paper Motion The DPU determines when paper must be moved and how far
to move it. It communicates this to the RTPU through the shared memory.
The RTPU processor performs some paper handling operations (such as
holdback on slews), but most RTPU paper handling is done by a dedicated
microcontroller called the paper feed controller (PFC).
The PFC moves paper by looking up motion profiles and driving a sequence
of motor positions to the mechanism driver board. If the motion is a dot row
or interline advance, it is synchronized to hammer firing by a signal from the
FTIC that tell the PFC when to move.
Ribbon and Shuttle Motion The ribbon and shuttle motors are controlled
by a microcontroller on the mechanism driver board. The RTPU interface to