Hardware manual

5.4 Multiport Devices in the /dev Directory,
The serial ports your multiport board uses depends on what kind of board you have. Some have their own
device names like /dev/ttyE27 (Stallion) or /dev/ttyD2 (Digiboard), etc. For various other brands, see see
devices.txt in the kernel documentation. Some use the standard names like /dev/ttyS14 and may be found in
configuration files that used as arguments to setserial. Such files may be included in a setserial or serial
package.
5.5 Making Legacy Multiport Devices in the /dev Directory
An installation script may do this for you. But if not, here's some examples of how to create a device name in
the /dev directory. If you use udev, MAKEDEV will not create devices in the device directory since this
directory is only in memory and will be lost when you turn off the computer. Instead it will create the device
indev/.static/dev directory.
For the names and numbers of other types of serial ports other than ttyS.. See devices.txt in the kernel
documentation. Either use the mknod command, or the MAKEDEV script. Typing "man makedev" may show
instructions on using it.
Using the MAKEDEV script, you would first become the superuser (root) and type (for example) either:
linux# MAKEDEV ttyS17
Or if the above doesn't work cd to /dev before giving the above command>. Substitute whatever your port is
for ttyS17.
Using mknod is a more complicated option since you need to know the major and minor device numbers.
These numbers are in the "devices" file in the kernel documentation. For ttyS serial ports the minor number is:
64 + port number (=81 for the example below). Note the "major" number is always 4 for ttyS devices (and 5
for the obsolete cua devices). So, if you wanted to create a device for ttyS17 using mknod, you would type:
linux# mknod -m 666 /dev/ttyS17 c 4 81
5.6 Standard PC Serial Cards
In olden days, PCs came with a serial card installed. Later on, the serial function was put on the hard-drive
interface card. In the 1990s and early 2000s one or two serial ports were usually built into the motherboard
(on-board). Most of them (as of 2002) use a 16550 but some use 16650 (32-byte FIFOs). But one may still
buy the individual PC serial cards if they need more serial ports. They can be used to connect external serial
devices (modems, serial mice, etc...). Only a tiny percentage of retail computer stores carry such cards. But
one can purchase them on the Internet. Before getting one for the PCI bus, make sure Linux supports it.
Here's a list of a few popular brands:
Byte Runner (may order directly, shows prices) http://www.byterunner.com•
SIIG http://www.siig.com/products/io/•
Dolphin http://www.dolphinfast.com/sersol.html•
Note: due to address conflicts, you may not be able to use /dev/ttyS3 with a IBM8514 video card (and some
Serial HOWTO
5.4 Multiport Devices in the /dev Directory, 21