Serial Communications (16C452)
Table 8-2
ZT 8809A I/O Port Assignments.
I/O Port
I/O Address
I/O Read Register
I/O Write Register
Base +
0
3F8h
Data Buffer Ch1
Data Buffer Ch1
1
3F9h
Intr. Enable Ch1
Intr. Enable Ch1
2
3FAh
Intr. Indent. Ch1
---
3
3FBh
Line Control Ch1
Line Control Ch1
4
3FCh
Modem Cntrl. Ch1
Modem Cntrl. Ch1
5
3FDh
Line Status Ch1
Line Status Ch1
6
3FEh
Modem Status Ch1
---
7
3FFh
---
---
0
2F8h
Data Buffer Ch2
Data Buffer Ch2
1
2F9h
Intr. Enable Ch2
Intr. Enable Ch2
2
2FAh
Intr. Ident. Ch2
---
3
2FBh
Line Control Ch2
Line Control Ch2
4
2FCh
Modem Cntrl. Ch2
Modem Cntrl. Ch2
5
2FDh
Line Status Ch2
Line Status Ch2
6
2FEh
Modem Status Ch2
---
7
2FFh
---
---
Note: Serial port 1 base is 3F8h, serial port 2 base is 2F8h.
8-17
