Where Is COM Port 1 On My Laptop? | Quick Fix Tips

Guide / By

COM1 lives in Windows under Device Manager > Ports; if no built-in serial jack exists, a USB-to-serial adapter can create COM1.

Laptops rarely ship with a nine-pin serial jack anymore. Even so, Windows still uses the same naming—COM1, COM2, and so on—for any serial interface, including ones created by adapters or docks. That means “where” COM1 lives is mostly a software view in Device Manager, not a physical hole on the chassis.

Find COM1 On A Windows Laptop: Fast Steps

  1. Press Windows + X, pick Device Manager.
  2. Expand Ports (COM & LPT). Look for entries like USB Serial Port (COM1) or Communications Port (COM1).
  3. If you don’t see a Ports branch, open the View menu and click Show hidden devices. Plug in your USB-to-serial adapter and watch for a new entry.
  4. Double-click the device → Port Settings → Advanced… to view or change the COM number.

Why Many Laptops Don’t Have A Built-In Serial Jack

Consumer models dropped the classic DE-9 connector years ago. USB took over, and makers shaved ports for size and weight. Business-grade machines sometimes add serial on a dock or a special adapter, but the norm is to use a USB-to-serial cable that presents itself as a “virtual” COM device in Windows.

What Counts As COM1 In Practice

COM1 is just the label Windows assigns to a serial interface. It might be:

  • A legacy motherboard header or dock connector mapped as COM1.
  • A USB-to-serial adapter that grabbed COM1 when first plugged in.
  • A Bluetooth serial profile or specialty device that took that number earlier.

Because numbers are handed out over time, your adapter might land on COM3 today and COM7 tomorrow, depending on what’s been attached. You can change that value so your terminal app always talks to the same number.

Change The COM Number (So Your Tools Always Find It)

  1. Open Device Manager → Ports (COM & LPT).
  2. Right-click your serial device → Properties → Port Settings → Advanced….
  3. Pick COM1 (or any free value) from the COM Port Number list, then press OK.

Tip: plug the same adapter into the same USB socket each time if you want Windows to keep assigning the same number.

Need a command-line quick check? Windows includes a change port tool and PowerShell cmdlets you can run without extra installs. Learn the syntax on Microsoft’s change port command page and the Get-PnpDevice cmdlet page.

Check COM1 From The Command Line

Quick Windows Commands

Run these in a terminal window (Windows Terminal or PowerShell) with normal rights.

# List all present serial devices in PowerShell
Get-PnpDevice -Class Ports | Format-Table -Auto

# See only the names (COM numbers)
[System.IO.Ports.SerialPort]::GetPortNames()

# Old-school: show current mappings (CMD)
change port /query

# Map a high-numbered port to COM1 for a DOS-era tool (session only)
change port com12=com1

The mapping created by change port lasts for the current session. For a lasting change, set the number in Device Manager as shown earlier.

When The Ports Branch Is Missing

If Ports (COM & LPT) isn’t listed at all, try these quick checks:

  • Use View → Show hidden devices.
  • Plug in your adapter and wait a moment while Windows loads a driver.
  • If nothing appears, install the driver that matches the chip in your cable (many use FTDI or Prolific). Then re-insert the adapter.

Still nothing? In Device Manager, open Action and try Scan for hardware changes. As a last resort, use Action → Add legacy hardware to reveal the Ports branch for troubleshooting.

Pick The Right USB-To-Serial Cable

A reliable cable saves hours. Look for a model that clearly lists the chip it uses and includes driver links for your version of Windows. Many terminal apps are happiest with FTDI-based adapters. Keep one as a standby in your bag; most weigh less than an HDMI dongle.

Test The Link With A Terminal App

After you confirm the COM number, open your terminal tool and set:

  • Port: COM1 (or the number you chose)
  • Speed (baud): usually 9600 or 115200
  • Data/Parity/Stop: 8-N-1 for many devices
  • Flow control: off unless the device requires RTS/CTS or XON/XOFF

If you see gibberish, pick the other common speed and try again. If the app can’t open the port, check whether another program already grabbed it.

Quick Fixes When COM1 Seems Busy Or Missing

  • Unplug and re-insert the adapter, then reopen the terminal app.
  • Test a different USB socket on the laptop.
  • Free a ghost assignment: in Device Manager, enable View → Show hidden devices, then remove stale serial entries.
  • If a high number was assigned (say COM14) and your app only lists COM1–COM8, change the number in the Advanced dialog.

macOS And Linux: What To Know

On a Mac, serial devices don’t use “COM” names. You’ll see paths like /dev/tty.usbserial-XXXX or /dev/tty.usbmodem-XXXX. To list candidates:

# macOS: show likely serial devices
ls /dev/tty.* /dev/cu.* 2>/dev/null

# Connect with screen (quit with Ctrl+A, then K, then Y)
screen /dev/tty.usbserial-XXXX 115200

On Linux, USB-serial adapters usually appear as /dev/ttyUSB0 or /dev/ttyACM0. A quick peek:

# Linux: list likely serial devices
ls -l /dev/ttyUSB* /dev/ttyACM* 2>/dev/null

# See recent kernel messages about serial devices
dmesg | grep -i tty

These systems don’t reserve a special “COM1” slot; you select the device path shown under /dev.

Hardware Clues On A Physical Laptop

If your notebook has a nine-pin jack on the side or back, it’s almost certainly serial. Many don’t. Business docks sometimes include one; if so, Windows will present it with a COM number when docked. You still confirm the value in Device Manager.

Make Your Setup Repeatable

  1. Choose a specific USB socket and keep using that one.
  2. Assign the number you want in the Advanced dialog.
  3. Label the cable and the COM number in your kit.
  4. Save a terminal profile for each device you work with.

Handy Reference Table

Connection Where You’ll See It Notes
Built-in or Dock Serial Device Manager → Ports (e.g., Communications Port (COM1)) Rare on thin laptops; common on some docks.
USB-To-Serial Adapter Device Manager → USB Serial Port (COMx) Can change the number in Advanced settings.
macOS/Linux USB Serial /dev/tty.usbserial-*, /dev/ttyUSB*, /dev/ttyACM* No “COM” label; pick the path shown.

FAQ-Style Quick Answers

Can I Force My Adapter To Always Be COM1?

You can request COM1 in the Advanced dialog. If another hidden device still owns that number, remove it first. Some apps can remap on launch, but a direct assignment in Device Manager is simpler.

My App Only Lists COM1–COM4 But Windows Gave Me COM12

Change the number in the Advanced dialog to a lower slot the app can see. If the slot is marked “in use,” it can still work if nothing real holds it—try it and test.

Do I Need A Driver For The Cable?

Often yes. Many adapters ship with FTDI or Prolific chips. Grab the matching driver from the maker’s page, then re-plug the cable so Windows binds it.

Bottom Line

On a modern notebook, COM1 is a software label. Open Device Manager to see which device—built-in, docked, or USB adapter—currently owns that label. If the number isn’t what you want, assign a new one and keep using the same USB socket to make it stick.