---
name: "ucom"
section: "4"
platform: "openbsd"
package: "man"
version: "8.0-current-20261101"
release: "OpenBSD 8.0-current (2026-11-01)"
platforms: ["linux", "freebsd", "openbsd"]
url: "https://new.carta.tech/ucom"
---

# ucom(4)

USB tty support

## NAME

**ucom** – USB tty support

## SYNOPSIS

**ucom\* at moscom?** **#** **MosChip** **Semiconductor** **MCS7703** **ucom\* at uark?** **#** **Arkmicro** **Technologies** **ucom\* at ubsa?** **#** **Belkin** **ucom\* at uchcom?** **#** **WinChipHead** **CH9102/343/341/340** **ucom\* at ucycom?** **#** **Cypress** **ucom\* at uftdi?** **#** **FTDI** **ucom\* at uipaq?** **#** **iPAQ** **ucom\* at ukspan?** **#** **Keyspan** **ucom\* at umcs?** **#** **MosChip** **Semiconductor** **multiport** **ucom\* at umct?** **#** **MCT** **ucom\* at umodem?** **#** **Standardized** **umodem** **ucom\* at umsm?** **#** **Qualcomm** **MSM** **ucom\* at uplcom?** **#** **Prolific** **PL-2303** **ucom\* at uscom?** **#** **simple** **USB** **serial** **adapters** **ucom\* at uslcom?** **#** **Silicon** **Laboratories** **CP2101/CP2102** **ucom\* at uslhcom?** **#** **Silicon** **Laboratories** **CP2110** **ucom\* at uticom?** **#** **Texas** **Instruments** **TUSB3410** **ucom\* at uvisor?** **#** **Handspring** **Visor** **ucom\* at uvscom?** **#** **SUNTAC** **Slipper** **U** **VS-10U** **ucom\* at uxrcom?** **#** **Exar** **XR21V1410**

## DESCRIPTION

The **ucom** driver attaches to USB modems, serial ports, and other devices that need to look like a tty. The **ucom** driver behaves like a [tty(4)](/tty/4.md): this means that normal programs such as [cu(1)](/cu/1.md) or [pppd(8)](/pppd/8.md) can be used to access the device.

The *portno* locator can be used to decide which port to use for devices that have multiple external ports.

## FILES

- */dev/ttyU?*

  tty devices

- */dev/cuaU?*

  call out devices (see [tty(4)](/tty/4.md))

## SEE ALSO

[intro(4)](/intro/4.md), [tty(4)](/tty/4.md), [usb(4)](/usb/4.md)

## HISTORY

The **ucom** driver appeared in NetBSD 1.5. OpenBSD support was added in OpenBSD 2.7.