My computer has no serial port at all, but there are /dev/ttyS0-ttyS3 files, why?

unimous · 03-28-2011, 11:53 PM

My notebook is Lenovo F41, and there is not a serial port at all, but why there are /dev/ttyS0-ttyS3 files?

Code:

$ ls -l /dev/ttyS*
crw-rw---- 1 root dialout 4, 64 Mar 29 09:46 /dev/ttyS0
crw-rw---- 1 root dialout 4, 65 Mar 29 09:46 /dev/ttyS1
crw-rw---- 1 root dialout 4, 66 Mar 29 09:46 /dev/ttyS2
crw-rw---- 1 root dialout 4, 67 Mar 29 09:46 /dev/ttyS3

zordrak · 03-29-2011, 09:28 AM

The presence of a device node is not based on whether the device exists. There's a lot more in /dev/ that you don't have.

Skaperen · 03-29-2011, 11:37 AM

In some cases the devices may well exist as part of a chipset, but have no external connection so the manufacturer can shave the connector costs off the price. You can try to access the device node to see if it at least tries to respond. I have seen at least one motherboard with serial ports that terminated in solder pads (too cheap to even put a header in).