Subj : NTVDM project update
To   : All
From : Nick Andre
Date : Thu Feb 06 2020 01:03 am

I received a very detailed email from the author of Net2BBS/NETFOSS, which is
a Telnet server for Windows. More specifically, the component NETFOSS allows
the Telnet server to execute the 16-bit BBS by means of a "hook" in the way
that NTVDM operates. To recap, NETFOSS is a 32-bit Windows dynamic link
library (DLL) which essentially handles the Telnet-to-FOSSIL passover. 16-bit
BBS/Comm stuff that is Fossil-aware, interacts with NETFOSS using the DLL.

My understanding from what I read is that the DOS emulation of NTVDM can call
Windows DLL's by means of actually executing an invalid or
normally unrecognised instruction from within the DOS session. The NTVDM
behavior on all 32-bit Windows "traps" the DOS call and instead acts on it as
a DLL function-request.

This technically makes sense as to how 16-bit BBS stuff and ZC1
processing happily co-exists with Windows executables and programs. A mixture
of both is currently in use on this system in several ways, without much
thought as to how thats actually possible. Reminds me of how OS/2 and DOS
executables were able to co-exist, or the other way around I think it was.

Anyhow - in Windows XP, Server 2003 and prior, the NETFOSS.DLL file could
reside in the same directory as the BBS/Telnet server.  Microsoft revised
NTVDM for Windows Vista and later 32-bit versions of Windows where for some
reason, DLL's loaded in this way must be placed in the \Windows\System32
directory.  Most likely done for security reasons or to stop notorious "DLL
hell" problems that have plagued Windows for many years.

The current behavior of this 64-bit NTVDM project testing is that the
NETFOSS.DLL cannot be found no matter what directory it is placed in. So, I
may need to escalate this to the developer team of this project to get their
feedback since it appears that the DLL is not loaded at all or is not even
being "trapped".

This is the *only* holdup I can see that prevents me from really porting
everything over - Its not a NetFoss problem, its a problem with the emulation.

The author of Net2BBS/NETFOSS is awesome and appears to be receptive to what I
was trying to accomplish.

Nick

--- Renegade vY2Ka2
* Origin: Joey, do you like movies about gladiators? (1:229/426)

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