Epson FX-870/1170 - Manual (Page 145)

Principles of Operation
E 2 PROM Control Circuit
Figure 6-31 shows the control circuit. The is non-volatile memory containing
information, such as the top-of-form position. Because the is a serial I/O device, the gate
array converts the parallel data (sent the host computer) into serial data.
Data Bus
SCK
SDA SDA
Figure 6-31. Control Circuit
6-30 Epson FX-870/1170