COM (hardware Interface)

COM (hardware Interface)

COM is the original, yet still common, name of the serial port interface on IBM PC-compatible computers. It might refer not only to physical ports, but also to virtual ports, such as ports created by Bluetooth or USB-to-serial adapters.

Most PC-compatible systems in the 1980s and 1990s had one or two ports, with communication interfaces defined like this:

• COM1: I/O port 0x3F8, IRQ 4
• COM2: I/O port 0x2F8, IRQ 3
• COM3: I/O port 0x3E8, IRQ 4
• COM4: I/O port 0x2E8, IRQ 3

As of 2007, most systems ship with one or no physical COM ports.