NTVDM will not open anything after updating

[MeatPony]

Hello

So I found out there was a couple of new commits recently, to both NTOSBE and NTVDMx64, so I decided to build it again in order to update my install. However I am unable to run literally anything dos. Nothing appeared to error out during building or installation, but running it just doesn't want to work. Picture above shows me trying to open the readme.com for Turbo C++ (Don't worry it doesn't spam open windows, I was just holding enter for le funny joke)

This does not only affect readme.com, I have tried all the 16 bit dos programs i have on my computer, and none of them worked.

[leecher1337]

Hm, so loader fires up NTVDM, but NTVDM bails out? Does DebugView show you any error output maybe? Is the 32bit loader ldntvdm.dll in SysWOW64 directory present and working and i.e not blocked by an Antivirus application? (The 32bit loader is required for NTVDM to start, otherwise Environment cannot be set up properly). Antivirus products are notorious for blocking the loader on every new build, unfortunately.

Theoretically also a bug in the loader could crash the NTVDM upon execution, so did you also change the loader .dlls or just the NTVDM.EXE? The loader dlls that you used on your previous working installation should theoretically also work on the newer installation, just for test. It's not easy to guess what is causing the problem by just seeing the launch error. So we should nail it down to either the loader DLL or the NTVDM.exe

Did you try the emendelson build under #7 for comparison?

[MeatPony]

I replaced the ldntvdm.dll in syswow64 from my build to the one from emendelson's build, and it appears to be working properly. However I do not like this solution.

[emendelson]

@MeatPony - Just to be clear - as my web page says, I do not build these downloads; what you download is not "emendelson's build." I get them from an anonymous source who makes the builds. Incidentally, I posted an up-to-date build today.

[MeatPony]

oh, sorry

[AbdullahTrees]

Incidentally, I posted an up-to-date build today.

Hey @emendelson ! I found the working NTVDM from your website but can you pleeease consider adding datestamps to the beginning/end of your article? I half thought the NTVDMx64 build I downloaded from your page was from 2010

[MeatPony]

is NTVDMx64 even that old?

[MeatPony]

The earliest commit on this repo says 2016

[leecher1337]

So this implies that it may be realted to change in the loader code from https://github.com/leecher1337/ntvdmx64/commit/9b966f587023e5c2e36270cdad895ec12ecc8e13 However only FindeResourceEx inline hook was added for 16bit icon parsing, nothing about the loader itself changed. I noticed, that the 32bit loader often is targetted by Antivirus programs (inclusing maybe Windows' own Defender). When you download current ldntvdm.dll for syswow64 from this repository, does it get targetted by Windows Defender maybe? When you use DebugView, the loader usually tells you what it is doing. So if you exchange the loader (you can simply rename the .dll in SysWow64 directory forth and back), does it load into 32bit process?

[Nukley]

Here is the debug log, also could you elaborate on what you mean by "(you can simply rename the .dll in SysWow64 directory forth and back)"?

00000002    0.00763370  [4000] VDMState=00000001    
00000003    0.00767370  [4000] LDNTVDM: Launch DOS! 
00000004    0.11221820  [4212] Hook_IAT_x64(D3D30000, ext-ms-win-kernelbase-processthread-l1-1-0.dll, BasepProcessInvalidImage, D37A2F0C)   
00000005    0.11226330  [4212] Hooked D5EA4790 -> D37A2F0C  
00000006    0.11235540  [4212] LDNTVDM: BasepProcessInvalidImageReal = D5EA4790 
00000007    0.11237320  [4212] LDNTVDM: BaseIsDosApplication = D5EC8EF0 
00000008    0.11241320  [4212] LDNTVDM is running inside ConHost.exe    
00000009    0.11247250  [4212] Hook_IAT_x64_IAT(BE020000, ntdll.dll, RtlAllocateHeap, D37A3530, D37ADB28)   
00000010    0.11252270  [4212] Hooked D6A3B7F0 -> D37A3530  
00000011    0.11256250  [4212] Hook_IAT_x64_IAT(BE020000, user32.dll, NotifyWinEvent, D37A3704, D37ADB20)   
00000012    0.11260760  [4212] Hooked D4CCCC10 -> D37A3704  
00000013    0.11265980  [4212] Hook_Inline(7ffcd4ccb500, 7ffcd37a1a58, 0)   
00000014    0.11271180  [4212] dwOrigSize detected: 7   
00000015    0.11286110  [4212] About to alloc page @7ffcd4caf000    
00000016    0.11288860  [4212] About to alloc page @7ffcd4cae000    
00000017    0.11291350  [4212] About to alloc page @7ffcd4cad000    
00000018    0.11293790  [4212] About to alloc page @7ffcd4cac000    
00000019    0.11296290  [4212] About to alloc page @7ffcd4cab000    
00000020    0.11298810  [4212] About to alloc page @7ffcd4caa000    
00000021    0.11301270  [4212] About to alloc page @7ffcd4ca9000    
00000022    0.11332460  [4212] About to alloc page @7ffcd4bff000    
00000023    0.11337550  [4212] Hook_Inline context=7ffcd4bf0000 
00000024    0.11340050  [4212] Hook_IAT_x64_IAT(D4CB0000, api-ms-win-core-file-l1-2-1.dll, ReadFile, D37A1974, D37ADB50)    
00000025    0.11342640  [4212] Hooking failed (-1). 
00000026    0.11345000  [4212] Hook_IAT_x64_IAT(D4CB0000, api-ms-win-core-file-l1-1-0.dll, ReadFile, D37A1974, D37ADB50)    
00000027    0.11347750  [4212] Hooked D3D55110 -> D37A1974  
00000028    0.11350330  [4212] ldntvdm Init done    
00000029    0.11639300  [4212] PrivateExtractIconsWHook(ntvdm.exe)  
00000030    0.16047961  [4212] EVENT_CONSOLE_START_APPLICATION PID 3532 
00000031    0.16221420  [4212] Before CreatEThread  
00000032    0.16298421  [4212] After CreatEThread   
00000033    0.16311580  [4212] ProcessInitializing = 1  
00000034    0.16525979  [4212] ProcessInitializing = 1  
00000035    0.16744100  [4212] Queued loader injection via APC @74FF9C20    
00000036    0.17658859  [4000] PrivateExtractIconsWHook(c:\windows\system32\ntvdm.exe)  
00000037    0.17715409  [4000] PrivateExtractIconsWHook(C:\windows\system32\imageres.dll)   
00000038    0.23926041  [3532] NTVDM: 24576K Memory: 15360K XMS, 0K EMS, 8192K DPMI

[AbdullahTrees]

The earliest commit on this repo says 2016

Hehe, well the first place where I heard of NTVDMx64 was on some Windows XP forum and then I googled and the first thing that lead to anywhere was emendelson's page.

[AbdullahTrees]

Here is the debug log, also could you elaborate on what you mean by "(you can simply rename the .dll in SysWow64 directory forth and back)"?

I'm not leecher1337, but I think he meant that you can switch the ldntvdm.dll from the setup files with the ones in SysWOW64 folder.

[leecher1337]

Stupid me, I just uploaded the wrong DLL on last commit, hopefully fixed now.

[Nukley]

appears to work now

[AbdullahTrees]

Can someone help me out with Turbo C++ btw? I wanted to use the Turbo C++ compiler for C compiling only (I remember I had that as a kid), but most of the stuff I'm finding online seems to be C++ compilers... How can I use C language on them?

[leecher1337]

https://vetusware.com/download/Borland%20Turbo%20C++/?id=169 C++ compilers usually are perfectly compatible with plain C programs, as C++ standard requires the compiler to fully support C anyway.

[AbdullahTrees]

No, wait you don't understand... I had a folder on my PC (the origin of these files are some time around 2010, no idea, my sister downloaded them, I was only 8 or 9 at the time) called 'TC' and 'TC++', and these were the executables inside them. The Turbo C++ executable ran at fullscreen, whereas the Turbo C thing ran in windowed and had a slightly longer window.

Secondly, The Turbo C compiler didn't save its files as .CPP, it always saved them as .C, without me even renaming it... and the C++ compiler did vice versa.

Maybe there are some configuration files that can be changed, in which case I'd ask for a way to configure them so I can run them both at fullscreen and make 2 copies, one for C and one for C++

[leecher1337]

Regarding fullscreen, I guess you mean the .pif file settings for DOS applications. Just go to the properties of the .exe file and there you can set whether it starts fullscreen or windowed:

In Turbo C++ in options/Environment/Preferences... you can set whether it uses a 50 or 25 line screen. In Options/Environment/Editor, you can set the default file extension.

[AbdullahTrees]

:OOO I knew it!! There was an option to run applications in windowed mode after all! Time to try out that Mavis.exe

EDIT: ........ Mavis.exe decides to run in fullscreen anyway ignoring the stipulations....

[leecher1337]

Yes, I already explained it to you, why this is the case

[Nukley]

Oops, Might've confused you, I am MeatPony, forgot to log back into that account.

[MeatPony]

Nukley is me, I wasn't lying :P