NEC PD78P078 User Manual
533
CHAPTER 23 EXTERNAL DEVICE EXPANSION FUNCTION
(3) External bus type select register (EBTS)
This register sets the operation mode of the external device expansion function. When the multiplexed bus
mode is selected, the P80/A0 through P87/A7 pins can be used as an I/O port.
It is set by an 8-bit memory manipulation instruction.
RESET signal input sets EBTS to 00H.
Figure 23-4. External Bus Type Select Register Format
7
0
Symbol
EBTS
6
0
5
0
4
0
3
0
2
0
1
0
0
EBTS0
Address
FF3FH
00H
After
Reset
R/W
R/W
0
1
Sets operation mode of external device expansion function
Multiplexed bus mode
Separate bus mode
EBTS0