Some of these commands are present in the AutoCAD command table, but are disabled, and therefore are not recognized as commands. They are included for the sake of completeness.

CommandIntroducedNotes
*SCROLLR12Resets the "pan" scroll bars.
.ACADSTATUSpre R12Creates ACAD.SLG in same directory as ACAD.EXE. The file contains an internal status log. [You must precede this command with an extra period to use it at the command line.]
.ACLTSTATUSR13Same as ACADSTATUS, except for AutoCAD LT. [You must precede this command with an extra period to use it at the command line.]
.SYSSTATUSR14Does nothing.
-OLDMTEXTR14Runs the R13 -MTEXT command.
ADIDUMPR13Does nothing.
AXISpre R12It just tells you it's a discontinued command (remember AXISMODE?)
CONTENTR14Does nothing. Could it be a prelude for the 'Content Explorer'?
CONVERTPOLYR14Convert both ways between old style polylines and the new lightweight polylines. This is a very useful one!
DLGCOLOR*R13Controls dialog colors in R13/DOS, does nothing in other versions.
*This command is documented in R13, but not in R14.
DRGINSERTR14Does nothing.
DUMPMEMALLOCR13Provides internal memory information.
DVBINR14Does nothing. Probably intended for importing VBA macro.
DVBOUTR14Does nothing. Probably intended for exporting VBA macro.
ENDSVR12An interesting variant of END, with a warning about being unable to save vector files(?).
FILEOPENR12A command-line only variant of OPEN. In R13, this command is issued when selecting a file from the MRU file list in the 'File' menu.
KABOOM!R13Does nothing. Looks fun, though!
KRISTIR13Creates cat_acad.h and cat_acad.rc in the ACAD.EXE directory. These files contain resource definitions for all loaded toolbar buttons. They don't look very useful to me, but I'll bet Kristi needed them.
MAKEBLKR14Does nothing.
OFFLINER13Warns that it is "not converted to AcDb yet", then does nothing.
OLDMTEXTR14Runs the R13 MTEXT command.
OLDMTPROPR14Runs the R13 MTPROP command.
PAINTERR13Does nothing in R13, runs _MATCHPROP in R14.
PRPLOTpre R12Tells you that it's a discontinued command (remember "printer plots"?)
RENDENVR14Does nothing.
SETENVR13Does nothing.
UNLOCKR13Does nothing.
VIEWTOOLBARR13Does nothing.
XDRGINSERTR14Does nothing.

Additional Information:

  1. Here's an intriguing command which crashes AutoCAD R13:
    ACRX_RESIDENT_COMMAND__DEFINE_MAX_BUFFER_SIZE_AS_64_CHARS_MAX_XX