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- Under SCO prior to 32v5 or Open Server 5, SCO observes the
- convention of using the last character of the tty file name
- (always an alpha character) to indicate whether a tty file name
- refers to the _direct_ (ignoring control signals) or to the
- _modem_ (observing control signals) access methods for the same
- physical port.
- A file name with an _upper case_ character refers to the modem
- access method. A file name with a _lower case_ character refers
- to the direct access method.
- /dev/tty1a refers the same physical port as /dev/tty1A, but with
- differing access methods.
- The choice of tty file names is established (by SCO) in pre-32v5
- UNIX by use of the kernel configuration file
- /etc/conf/node.d/sio. Some sample contents:
- sio tty1A c 128
- sio tty1a c 0
- Note the choice of "tty1A" and "tty1a" in the file is completely
- `arbitrary' from the point of view of the kernel building
- facility. The convention is set by the system architect who
- chose to assert the name relationship we have enjoyed, lo, these
- many years. A simple examination shows this choice to be FAR
- superior to such decisions as "acu0", "ttyd0" and "ttya" found on
- certain unnamed "systems." SCO follows their convention for
- pre-32v5 all the way back to the very advent of Xenix (and SCO
- UNIX of course).
- A problem arises with third party vendors who do not use
- the convention (maybe they have 900 port boards).
- The result is that *NO* convention exists for lock names of this
- type (like the foreign system's acu0, ttyd0, ttya case).
- The solution for this is that in 32v5 and later, SCO now mandates
- that lock file names be now constructed by converting *ALL*
- filename characters to lower case, not just the last. This does
- not cover the degenerate case of /dev/ttyHotTubDcdParadise01 and
- /dev/ttyHotTubDownAndDirty01, but just think of it as evolution
- in action :).
- This means:
- /dev/ttyA08 locks to LCK..ttya08
- /dev/ttya08 locks to LCK..ttya08
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