What Is a Com1 Port?

What Is a Com1 Port?

A COM1 port is a serial port on a computer system. A serial port is a socket making it possible for peripheral devices like a mouse or a modem to link to the computer system via a cable. Serial ports have been changed by the little Universal Serial Bus Connectors. More recent computers do not have a COM1 port; they link to peripherals via a USB port rather.

Serial Port

A serial port gets its name because information travels down a cable leading from a serial port in series, rather than parallel. Data moves around inside a computer along 8 parallel wires. A byte of data leaves one point and comes to another all at once. A byte is 8 bits of information, each bit traveling down one of the parallel wires. A parallel cable television, connected to a parallel port continues this configuration, however a serial port sends all the data down the same wire and so needs to restructure the order of the data so that each bit follows the others in order, rather than 8 bits traveling simultaneously down parallel wires.

What Is a Com1 Port?

Interaction Port

An old computer system would have one parallel port, perhaps one “serial port” and two “COM” ports. The COM ports are serial ports. The “COM” represents “interaction” and the calling convention was created by Microsoft for its DOS operating system. It was possible to create a virtual COM port by mapping numerous “COM” names onto the exact same physical port.


A parallel cable television appears like as ribbon, made up of a row of wires with their plastic casing fused together; a serial cable television is one thick cable. The hint to what lies inside the cable jacket comes from the port. This is a large head with two rows of pins (male) or holes (woman). Although serial ports carry information down one wire, the cable includes a collection of wires. Each is used for a different purpose. Data journeys far from the computer down one pin and into the computer system down another pin. The recognition of the use of each pin is puzzled by the presence of two various designs for the connector. The general requirement for the adapters is called “RS-232,” however this consists of two layouts. A 25-pin connector and a 9-pin connector. The 25-pin connector is called a “DB-25” and the 9-pin port is called a “DE-9.” The other pins on the DE-9 carry control signals. On the DB-25, only 10 of the 25 pins really link to wires, and only two of the 10 linked pins bring information. The rest are for control information and for an electrical ground wire.


The large size of the serial adapters obstructed the process of miniaturization of laptop computers. The case of the computer could not be made thinner than the requirements of the RS-232 socket hosing. Computer system manufacturers have switched over to USB adapters, which do not carry the COM1, COM2, COM3 naming convention. COM1 ports are slipping into calculating history.

Morris T. Parson, Tech Support

Leading specialist in electronics and engineering. Author of dozens of articles on various topics from the world of hi-tech. Sound independent analysis of products, exploring new niches and global trends is his special passion.

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