Printronix P9012 Maintenance Manual page 57

(DCU)
HOST
CONNECTION
INPUT DATA
THROUGH DMA CONTROLLER
68B44
(DCU)
SELF–TEST
SELECT FROM
FRONT PANEL
SOFTWARE
Principles of Operation
FRONT PANEL
PRINTER SETUP
PRINTER ENABLE
INPUT DATA
BUFFER
(IN DYNAMIC RAM)
ASCII DATA (DCU)
BUILD DOT IMAGE BUFFER (DIB)
FROM LOOK UP TABLES IN FONT
PUT INTO DYNAMIC RAM (DCU)
SYNCHRONIZE THE TIMING TO
THE CODE WHEEL (MPU)
SOFTWARE (MCU)
DEMAND HAMMER LOAD (MCU)
DATA SHIFTED OUT TO HAMMER DRIVER (DCU)
FIRE HAMMERS
ON NEXT MPU
ALL DOTS IN ROW PRINTED ?
N
Figure 2–29. Operation Flow Diagram
(DCU)
CONTROLLED BY SOFTWARE
EXECUTED BY HARDWARE
CONTROLLED BY SOFTWARE
EXECUTED BY HARDWARE
(MCU)
SOFTWARE TIMERS
SOFTWARE DECISION
Y MOVE
PAPER
(MCU/MECH
DRIVER)
2–39