Specifications

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