Ampro Corporation 486E - Manual (Page 29)

Product Reference
2–13
ROM-BIOS Installation of the Serial Ports
The ROM BIOS normally supports Serial 1 as the DOS COM1 device, Serial 2 as the DOS COM2
device, and so on. If a serial port is disabled and there is no substitute serial port in the system, the
ROM-BIOS assigns the COM designations as it finds the serial ports, starting from the primary
serial port and searching to the last one. For example, if Serial 1 is disabled, the ROM-BIOS
assigns COM1 to Serial 2 (unless another Serial 1 is discovered). The ROM BIOS scans I/O
addresses for serial ports in the following order: 3F8h, 2F8h, 3E8h, and 2E8h.
Serial Port Connectors (J11, J13)
Serial 1 and Serial 2 appears on connector J11. Serial 3 and Serial 4 appear on connector J13. Both
connectors are wired the same, J11 for serial 1 and 2, and J13 for serial 3 and 4. Table 2–8 details
the connector pinout and signal definitions for both ports. The table also identifies the pin numbers
where each signal must be wired for compatibility with standard DB25 and DB9 connectors. A flat
ribbon cable connects the header to a standard DB9 connector.
Note
PC serial ports are typically equipped with male DB9 connectors.