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xms driver not installed unable control a20 line

  • 1.  xms driver not installed unable control a20 line

    Posted 03-25-2013 07:34 PM



    I am trying to reimage a optiplex 790 with a windows 7 32 bit version. my GHOST CAST version is I have created images for optiplex 780's before with no problem. i really dont know what the issue is, any info about this is much appreciated.



  • 2.  RE: xms driver not installed unable control a20 line

    Posted 03-26-2013 06:31 AM


    Some years ago reports of failures to allocate memory started appearing in Dell machines; this is due to a design fault in the machine BIOS; there are a number of BIOS APIs to report the available extended memory in the machine, and the DOS-extender software used to run 32-bit code in DOS tries a number of them in sequence.

    In many Dell machines, all these various APIs return a single fixed size, typically 16Mb, which is the capacity limit of the very oldest of the APIs. On normal BIOSes all the APIs return different sizes depending on the era in which they were introduced, but Dell machines force Ghost to work in merely 16Mb of memory.

    The workaround I developed for this many years ago was to ask customers to use the FreeDOS equivalent of the classic DOS HIMEM.SYS extension. That utility understands the relatively new ACPI data table BIOS API introduced in the Windows 95 era, which is the only BIOS API that works properly in these Dell models. This then makes the results of that one working API available to Ghost's DOS extender via the XMS API, and so running the FreeDOS HIMEM.EXE will let Ghost use a great deal more of the installed memory than a mere 16Mb.

    Unfortunately because FreeDOS is not licensed cleanly it can't be bundled or redistributed by Symantec alongside Ghost, but it's easy enough to obtain this tool by itself and include it in the PC-DOS templates used by the Ghost Boot Wizard, since it does work as a drop-in replacement for the IBM one.