Epson FX-870 Service Manual page 139

Principles of Operation
Table 6-5 lists the fimctiona of the main componente of the CO94 MAIN.
PROM (iC3)
RAM (iC2)
6-24
Receives data from the host computer and loads it to the input buffer in
RAM. Expands the input data held in the buffer to create image data.
Loads the image data to the image buffer in RAM. Transfers the image
parts, such as the motors.
This gate array mainly performs the following five functions:
Memory management
l
Centronics I/F control
l
Control panel control
l
l
Printhead drive circuit control
l
The PROM contains the program that runs the CPU.
The RAM contains the CPU working area and the buffers.
The E*PROM is used to store information such as the top-of-form
position.
Drive circuit for PF motor
Drive circuit for CR motor
Epson FX-87W1170