Epson FX-870/1170 - Manual (Page 137)

Principles of Operation
Control Circuit Operation
The control circuit consists of two circuit boards: the CO94 MAIN (main control circuit board) and
the CO94 PNL (control panel circuit board). This section describes the operation of these boards.
Control Circuit Operation Overview
The CPU on the CO94 MAIN is an microprocessor (9.83 MHz). It oversees
control of all the components of the printer. The gate array contains various memory
management functions that control the memory assignment and areas. The output signals
each detector are sent to the analog input port of the CPU. The signals from the control panel
are sent to the gate array, which in turn, sends LED signals to the control panel. The two motors
(CR and PF) are controlled by signals sent from the stepping motor control port of the CPU. Figure
6-23 shows the control circuits in block diagram form.
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Figure! Control Circuit Block Diagram
Epson 6-22