DOS Undocumented

Some "hidden" features":
ATTRIB ,
Same as ATTRIB -A -H -R *.* Quick way to change attributes of a dir.

COMMAND.COM /F
Always assume (F)ail on floppy drive errors.

DIR ,
Shows all files, hidden and system too!

FDISK /MBR
Write -only- a new master boot record.

TRUENAME <filename>
Shows path, ignoring SUBST, ASSIGN,...

VER /R
Show DOS revision number and status.

FORMAT /AUTOTEST
Format a floppy, no questions asked. (Information from Cheat Machine)