Epson FX-870/1170 - Manual (Page 41)

Printer Features
C094 MAIN Board Assembly (Main Control Circuit Board)
Basically, the same board layout is used in both the model and the
column model. The CPU on this board controls all the main functions of the printer.
It consists of a CPU, an gate array, an a
PSRAM, a MASK ROM, motor drivers, and head drive transistors.
PF MOTOR
DRIVER CPU
CR MOTOR
M A S K R O M
HEAD DRIVE ARRAY
TRANSISTORS
Epson 1-29