The standard port adresses are given below. Most PCs have them. If you are using IBM PS/2, equipped with a micro-channel bus, different addresses and interrupt requests can be expected. Just like LPT ports, base adresses for ÑÎÌ-ports can be obtained from the data range in BIOS.
Standard Port Addresses
The table below contains the address having the addresses for COM-ports in BIOS data range. Each address has two bytes.
COM Port Addresses in the BIOS Data Area
|0000:0400||COM1's Base Address|
|0000:0402||COM2's Base Address|
|0000:0404||COM3's Base Address|
|0000:0406||COM4's Base Address|