But wrong. The ITT XTRA MS-DOS 2.11 Reference had a chapter on Xenix
compatibility which explained this stuff in detail; I've never seen it in
other DOS manuals.
CP/M, and therefore DOS 1.x, used / to signal parameters --- and the CLI
knew about this, such that "FOO/X" would be parsed as a command "FOO" with
an argument "/X". To maintain compatibility with DOS 1.x while providing an
upgrade path to Xenix compatibility, the SWITCHAR could be set via a DOS
call or CONFIG.SYS; if set to anything but "/", "Xenix-like" command parsing
was used and DOS commands could be invoked with switches preceded by the
specified SWITCHAR; 3rd party DOS programs were supposed to use another DOS
call to get the SWITCHAR and use it appropriately. ("Xenix-like command
parsing" meaning that "FOO-X" was not treated as command "FOO" with switch
"-X" if the SWITCHAR was "-".) There was also AVAILDEV which, if set to NO,
disabled "bare" device references such as "CON", and you had to use
"\DEV\CON" or "/DEV/CON" instead; all the standard DOS 2.11 programs used
the \DEV prefix internally so they would work with AVAILDEV=NO, and again
3rd party programs were supposed to query AVAILDEV and behave appropriately.
That chapter also stated that DOS 3.x would default to a SWITCHAR of "-" and
would add limited multitasking features, and that DOS would gradually be
migrated to full Xenix compatibility, followed by its being fully replaced
by Xenix (!). I sometimes wonder what the computing world would be like if
Microsoft had actually done this....
--
brandon s. allbery os/2,linux,solaris,perl allbery@kf8nh.apk.net
system administrator kthkrb,heimdal,gnome,rt allbery@ece.cmu.edu
carnegie mellon / electrical and computer engineering kf8nh
We are Linux. Resistance is an indication that you missed the point.
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