Oki Microline 3320 Maintenance Manual page 144

80C51
RST
TD
RD
IF WR
DB0 to DB9
LS245
+5 VD
±9 V power
10 VAC
supply circuit
+5 V
ADR latch
2764
ROM
8 KB
RAM
8 KB
+9 V
–9 V
+5V
0V
Figure C-2-1 Block Diagram
C – 3
CN1
TD
RD
Serial data
control line
Bus line
Control line