User manual

10. Parallel I/O
90
16C50A Enhanced Operating Mode
Enhanced operation adds extended event sense and input debounce capabilities. It is
selected with four consecutive writes of 07h, 0Dh, 06h, and 12h to I/O port address 7Dh
immediately after a power cycle or a reset. Three enhanced register banks are selected
by programming bits 6 and 7 of I/O port 7Fh with a 00 for bank 0, a 01 for bank 1, and a
10 for bank 2. Ziatech Industrial Computer Systems software configures the 16C50A for
enhanced operation. The Ziatech BIOS initializes the ZT 8904 for enhanced operation
at BIOS revision 4.41 or later.
Enhanced Bank 0 I/O Port Addressing
Address Register Read Operation Write Operation
0078h Port 0 Data MOD00-MOD07 MOD00-MOD07
0079h Port 1 Data MOD08-MOD15 MOD08-MOD15
007Ah Port 2 Data MOD16-MOD23 MOD16-MOD23
007Bh System Register 0 ----- -----
007Ch System Register 1 ----- -----
007Dh System Register 2 ----- -----
007Eh Reserved ----- -----
007Fh Write Inhibit/Bank Address Status Control
Enhanced Bank 1 I/O Port Addressing
Address Register Read Operation Write Operation
0078h Port 0 Event Sense Status Control
0079h Port 1 Event Sense Status Control
007Ah Port 2 Event Sense Status Control
007Bh Reserved ----- -----
007Ch Reserved ----- -----
007Dh Reserved ----- -----
007Eh Event Sense Manage Status Control
007Fh Bank Address Status Control