Epson LQ-570 Service Manual page 22

REV.-A
Table 2-5 lists the functions of the main components and circuits of the printer. The CPU converts the
print data sent from the host mmputer to image data (the print image). The image data is then loaded
to RAM. Each line of data is processed sequentially. The CPU transfera the print data to the printhead
drive circuit. The CPU sends the printhead drive pulse to the printhead drive circuit. The length of this
pulse corresponds to the printhead drive voltage. The head drive circuit then outputs the head drive
signal.
G/A E05A86
Location
E05A50
Print Data
Image Data
Transfer
Date Latch and
Delay control
Figure 2-18. Data Flow
Table 2-5. Functions of the Main IC and Circuits
Receives data from the host computer and loads the data to the input buffer in
RAM (under interrupt processing control). Expands the input data held in the
buffer to create image data. Loads this image data to the image buffer in RAM.
Transfers the image data to the printhead drive circuit. It also controls various
This is a gate array consisting of three components mnfigurd on a single chip:
Memory Management Unit
Handles CPU memory in ROM, RAM, and mask ROM, and assigns addresses
for other devices.
Parallel Interface (Parallel I/F)
Holds the parallel interface functions.
Reset Circuit
Contains the circuit that generates the /RESET signal.
2-14
RAM
Input
Buffer
- - - - - -
Image
Buffer
Functions