PRB: Phar Lap Error 58 Running Visual C++ on Read-Only Drive

• Microsoft Visual C++ for Windows, versions 1.0 and 1.5
• Microsoft Visual C++ 32-bit Edition, version 1.0
• Microsoft Macro Assembler for MS-DOS, versions 6.1, 6.1a, and 6.11

SYMPTOMS

An attempt to execute NMAKE.EXE, CL.EXE, LINK.EXE, or MASM.EXE in MS-DOS when Windows is not running fails and generates the following message:

   Phar Lap err 58: Can't create VM swap file of size 0 in
   directory <root directory name>:\

With Visual C++ for Windows and MASM version 6.1a, the error can also occur when the TMP environment variable is invalid or points to a read-only drive. For additional information about the TMP problem, please search in the Microsoft Knowledge Base on the following words:

   Phar Lap RW1016

CAUSE

Visual C++ is installed on a read-only drive, possibly a network drive. The error occurs because the DOSXNT MS-DOS extender attempts to create a virtual memory swap file on the drive DOSXNT runs from when the operating system does not support virtual memory.

RESOLUTION

To work around this problem, you can run DOSXNT on a read/write drive listed in your PATH MS-DOS environment variable. Or you can specify one of the following environment variable settings to prevent DOSXNT from attempting to create a swap file on the read-only network drive:

• Set the DOSX environment variable to prevent DOSXNT from using any virtual memory. Edit your AUTOEXEC.BAT file to include the following:

        set dosx=-novm
  

  With this option, you may run out of memory due to virtual memory not being used. If this is the case, use the second solution to set up a swap directory for the virtual memory.

  -or-

• Set the DOSX environment variable to specify where DOSXNT creates the virtual memory swap file. Edit your AUTOEXEC.BAT file to include the following

        set dosx=-swapdir <path>
  

  where <path> specifies the drive and directory on which to create the temporary swap file.

• Set a TMP environment variable that points to a read/write drive with enough free space for temporary files. If the TMP environment variable already exists, check to see that it is valid and pointing to a read/write drive. The TMP environment variable works only for the version of DOSXNT that comes with Microsoft Visual C++ for Windows version 1.0 and Microsoft MASM 6.1a.