Full-screen DOS Window Is Split with Some Number 9 Video Cards

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Article ID: 197538 - View products that this article applies to.
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Starting a full-screen command prompt on some Number Nine video adapters may result in a split-screen doubling of the full screen.


Vga.sys needs to set the character cell height for the MS-DOS mode. Character cell height is held in the lower 5 bits of the VGA register CR9. However, Vga.sys destroys the upper 3 bits of CR9 when writing the character cell height into the lower 5 bits of the register. The state of one of those upper three bits is required by the flat-panel MS-DOS mode.


To resolve this problem, obtain the latest service pack for Windows NT 4.0 or Windows NT Server 4.0, Terminal Server Edition. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:
152734 How to Obtain the Latest Windows NT 4.0 Service Pack

If obtaining the service pack at this time is not a viable alternative, you can contact Microsoft Product Support Services to obtain the fix. For a complete list of Microsoft Product Support Services phone numbers and information on support costs, please go to the following address on the World Wide Web:

The English version of this fix should have the following file attributes or later:

   Date      Time                 Size    File Name     Platform
   10/27/98  11:08a                14,704 Vga.sys       (x86)
   10/27/98  11:08a                22,832 Vga.sys       (Alpha)


Microsoft has confirmed that this is a problem in Windows NT 4.0 and Windows NT Server 4.0, Terminal Server Edition. This problem was first corrected in Windows NT 4.0 Service Pack 4.0 and Windows NT Server 4.0, Terminal Server Edition Service Pack 4.


Article ID: 197538 - Last Review: November 2, 2013 - Revision: 3.0
Applies to
  • Microsoft Windows NT Workstation 4.0 Developer Edition
  • Microsoft Windows NT Server 4.0 Standard Edition
kbnosurvey kbarchive kbbug kbfix kbqfe KB197538

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