
DATA SOURCE MANAGER

The TWAIN system uses a data source manager implemented as a DLL under Windows.

This is a single shared DLL that may have a different name and different 
location depending on the TWAIN version.

If the TWAIN data source manager is not installed on your system or out of date
copy the latest DLL as indicated in section 1 below.

There are three different DLL names:

1. TWAINDSM.DLL:

This is the latest recommended and maintained data source manager. This is tricky 
because there are two versions of this DLL one 32 bit, and one 64 bit. 

On a 32 bit OS, it is usually found in C:\Windows\System32.

On a 64 bit OS, you can have both copies. The 64 bit version in c:\windows\system32 
and the 32 bit version in C:\Windows\SysWOW64\

Envision includes these two DLL's but the latest versions can be found at,

http://sourceforge.net/projects/twain-dsm/


2. TWAIN.DLL:

The original TWAIN 1.X DLL usually found in C:\Windows folder. This can be 32 bit or
64 bit on a 64 bit OS.


3. TWAIN_32.DLL:

A 32 bit version of the data source manager usually found in C:\Windows on a 64 bit 
OS.



SCANNER DRIVERS

Each scanner model must install their on driver that will be controlled by
the data source manager.

32 bit drivers for 32 bit applications (even when running under a 64 bit OS)
are installed in folder C:\Windows\Twain_32.

64 bit drivers for 64 bit applications are installed in folder 
C:\Windows\Twain_64.

So if your scanner driver does not install a sub folder in the Twain_64 folder,
that means it is not available for 64 bit applications.
