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Undocumented

What's your Truename

DOS version 4.0 added an undocumented command to its list. TRUENAME. This command would return the actual Truename of the file. For instance, if you used

  SUBST G: C:\TEMP\BAK

so that any file in this directory could be accessed

  G:FILE1.BAK

and issued the command

  TRUENAME FILE1.BAK

DOS would return

  C:\TEMP\BAK\FILE1.BAK

Along with the TRUENAME command came the DOS interrupt service. Service 60h. However, this interrupt service was included with DOS 3.0. Here are the register uses:

 On entry:
   AH = 60h
   DS:SI -> ASCIZ filename or path
   ES:DI -> 128-byte buffer for truename

 Return:
   CF set on error
      AX = error code
   CF clear if successful
      ES:DI -> 128-byte buffer of truename

Try it out. See what you come up with. ¥

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