Windows 10 Weird ACSII characters in NTDVM Windows 10

  • Thread starter Thread starter Robert Lenk
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Robert Lenk

In anticipation of the withdrawal of support for Windows 7 in January I am starting to transition my company’s computers to Windows 10. We have used Win 7 32 bit in order to use long standing custom DOS application. It has run in NTVDM faultlessly with the advantage that it can make calls to the external Windows system such as displaying and printing PDF files.

I have downloaded the Windows 10 update tool (32 bit of course) from Microsoft and attempted the transition on the first computer. I ran it with the option to keep all programs and data. Surprisingly, it ran without trouble with the result that all the Windows programs work as expected under the new Win 10. That is, with the exception of NTVDM.



In itself, NTVDM appears to work just fine. But the extended ASCII character set is displaying some weird characters. Since we use some of the extended characters (eg, £, ½, º, ±, ©, ®, µ) this will be a problem for us.



Under Win 7 in order to display the correct ASCII extended codes we added the following line to the batch file that calls the DOS application:



C:\Windows\System32\KB16 UK,850,C:\Windows\System32\KEYBOARD.SYS



That gave the ‘correct' ASCII extended character set as displayed here:





However, under Win 10 this displays as (‘incorrect' characters highlighted):





I notice that both KB.COM and KEYBOARD.SYS are present in the same C:\Windows\System32 folder in Win 10. So why is a different extended character set displaying?



I have configured NTVDM under Win 10 to ‘Use legacy console’. I notice a new parameter ‘Current code page’ configured for 'OEM – Multilingual Latin I’ which can't be altered whether in legacy console or not.



In Control Panel, Region Settings, the system locale is set to ‘English (United Kingdom)'. I don't know if this affects (or should affect) NTDVM in Win 10.



Interestingly, this behaviour seems to only affect the raster font. When selecting either of the TrueType fonts, Consolas or Lucinda Console, the ‘correct’ extended character set is displayed.



However, the TrueType fonts introduce screen artefacts (mainly when toggling through menus) which don’t appear with the raster font. So I’d prefer to use the raster font in Win 10 as I did with Win 7.



I’ve searched the internet for possible solutions but can find nothing. Maybe people don’t use the extended ASCII set so they don't see a problem.



I have recently looked at alternatives to NTVDM. Although vDOS would appear to be the answer for my application (both 32 and 64 bit) I can’t get it to work. NTVDM is simple, comes with Windows (32 bit) and I know it works (until now).




Would much appreciate some assistance with this.

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