Serial Interface; Serial Port Addressing And Interrupts - NEC POWERMATE PROFESSIONAL - SERVICE MANUAL 05-1997 Service Manual

1-14 Technical Information

Serial Interface

The system has two 16C550 UART-compatible serial ports (COM1 and COM2) integrated
on the I/O controller. The serial ports support the standard RS-232C interface and the IR
interface (see Table 1-7). The buffered high-speed serial ports support transfer rates up to
19.2 KB. These ports allow the installation of high-speed serial devices for faster data
transfer rates.
I/O addresses and interrupt levels for the two channels are given in Table 1-7. The interrupt
level is selectable via Setup to either IRQ3 or IRQ4. Software selectable base addresses are
3F8h, 2F8h, 3E8h, and 2E8h.
Table 1-7 Serial Port Addressing and Interrupts
Starting I/O Address
3F8h
2F8h
3E8h
2E8h
* Used for IrDA data transfer
See Section 2, "Setup and Operation," for information on resetting the port through Setup.
Serial interface specifications include:
T
Baud rate up to 19.2 KB per second
T
Word length - 5, 6, 7, or 8 bits
T
Stop bit - 1, 1.5, or 2 bits
T
Start bit - 1 bit
T
Parity bit - 1 bit (odd parity or even parity).
Serial interface signals are output through the system board's 9-pin, D-subconnector. The
connectors are located at the rear of the system unit. Pin locations for the serial interface
connector are shown in Appendix A.
NOTE: Any interrupts used for the built-in
serial ports are not available for ISA parallel
ports.
Interrupt Level
IRQ04
IRQ03
IRQ04
IRQ03
Port
COM1
COM2*
COM3
COM4