Back to square one. The cua lock files should also go in this directory, but use of cua devices is now discouraged. The cua devices will probably still be around for some time to provide a period of backward compatibility, but in time they will be retired. Most software dealing with serial tty devices provides a compile-time option to specify the location of the lock files. This is ugly, but it will work.
Minor numbers are identical for both types of serial devices.
Its minor number will be 65, and its major number will be 4 for normal use. There should be a device called ttyS1 that has these numbers. If there is no device with major number 4 and minor number 65, you will have to create one. Sometimes they will be owned by root , and other times they will be owned by another user, such as uucp in our example. However, you cannot use modem in one program and the real device file name in another.