DOCUMENT:Q115238  02-NOV-2001  [vbwin]
TITLE   :HOWTO: Get and Set Diskette Media ID in VB for MS-DOS
PRODUCT :Microsoft Visual Basic for Windows
PROD/VER::1.0
OPER/SYS:
KEYWORDS:

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The information in this article applies to:

 - Microsoft Visual Basic for MS-DOS 1.0 
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SUMMARY
=======

This article shows by example how to call interrupts to get and set the media ID
for a diskette. The example also gets and sets the volume serial number and the
volume label.

WARNING: One or more of the following functions are discussed in this article;
VarPtr, VarPtrArray, VarPtrStringArray, StrPtr, ObjPtr. These functions are not
supported by Microsoft Technical Support. They are not documented in the Visual
Basic documentation and are provided in this Knowledge Base article "as is."
Microsoft does not guarantee that they will be available in future releases of
Visual Basic.

MORE INFORMATION
================

The following example uses MS-DOS interrupt (&h21), functions )&h440D),
and minor code (&h46) to set the volume label and serial number for the
specified drive.

This information can be found in any MS-DOS programmer's reference, for versions
of MS-DOS beyond 5.0.

Code Example
------------

   ' Note that you will want to load the VBDOS.QLB file when starting
   ' VBDOS to get this program to run.

   ' $INCLUDE: 'vbdos.bi'

   TYPE midstruc

      midinfolevel AS INTEGER       ' Information level.
      midserialnum AS LONG          ' Serial number.
      midvollabel AS STRING * 11    ' ASCII volume label.
      MidFileSysType AS STRING * 8  ' File system type.

   END TYPE

   DIM regs AS regtypex
   DIM ms AS midstruc

   ms.midserialnum = &HFFFFFFFF    ' Set the new volume serial number.
   ms.midvollabel = "SIDEHACKERS"

   regs.ax = &H440D
   regs.bx = 1                     ' Specifies drive A (2 for B, 3 for C..).
   regs.cx = &H846
   ' Remove the apostrophe from the following line to change it from a comment
   ' to an executed line if you want to retrieve the current values of the
   ' volume label and the serial number for the specified drive:
   ' regs.cx = &H866
   regs.ds = VARSEG(ms)
   regs.dx = VARPTR(ms)

   CALL INTERRUPTX(&H21, regs, regs)

   CLS

   IF (regs.flags AND 1) THEN       ' Check for error.

      PRINT "problem : "; regs.ax   ' Print error number.

   ELSE

      PRINT HEX$(ms.midSerialNum)   ' Print successful return values.
      PRINT ms.midVolLabel
      PRINT ms.midFileSysType

   END IF

Additional query words:

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Keywords          :  
Technology        : kbVBSearch kbAudDeveloper kbZNotKeyword3 kbVB100DOS
Version           : :1.0
Issue type        : kbhowto

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