Epson 2070 - LQ B/W Dot-matrix Printer Service Manual page 71

LQ-2070 Service Manual
The following figure shows the data flow from the host computer to the printhead. Data sent from the host
computer is converted to image data and transmitted to the printhead through the gate array.
Option I/F
Parallel I/F
Host
Com puter
The following table lists the each function of the main components of the C186 MAIN board.
IC Location
CPU IC1
Gate Array IC2
EEPROM IC 8
ROM IC 3
RAM IC 5
CG IC 7
SLA7024M IC 12
TEA3718SDP IC 11,14
Rev.A
Gate Array
E0 5B24 YA
Data latch
and
data output
Pr i nthe ad d r ive
cir cuite
Figure 2-31 Data Flow
Table 2-7 Functions of the Main Board
Receives data from the host computer and sends it to the input buffer
in RAM (under interrupt processing control). Extends 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
driver circuit.
Controls the functions below:
• Controls output data from the internal block
• Memory management
• Address latch of the address/data bus from the CPU
• Clock control unit
• Bit manipulation
• Interface control
• Expanded parallel port
• Printhead control
• Motor control
An electrically writable and erasable ROM used to hold information
such as the TOF position and bidirectional adjustment value.
The ROM contains the program that runs the CPU and holds the
character design (also called the character generator).
The RAM contains the CPU working area and the buffers
The CG contains the bitmap fonts for each character table
Driver circuit for the CR motor
Driver circuit for the PF motor
C P U
T M P9 6 C 0 4 1 AF
Print data
conversion 1
Print data
conversion 2
Im age data
transfer
Function
Operating Principles
R A M
Input
Buffer
Line Edit
Bu ff er
Image
Buffer
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