Notice: Use Java version 1.8. See further below for more information.
For more information go to https://www.bt747.org
From the current location, you can:
Try the desktop version of BT747: BT747_J2SE.jnlp
Install the desktop version of BT747: BT747_J2SE_Install.jnlp
Development version: BT747_J2SE_Latest.jnlp
Install development version:: BT747_J2SE_Latest_Install.jnlp
Launch development version using RXTX2.2:: BT747_J2SE_Latest_rxtx2_2p2.jnlp
Install development version using RXTX2.2:: BT747_J2SE_RXTX2.2_Latest_Install.jnlp

Important notice

You must run BT747 using Java Version 1.8. Either from Oracle or using OpenJDK.

On windows you an often find one already installed somewhere in "Program Files" or "Program Files (x86)" for some other software. You must run BT747 using a Java Version 1.8. Either from Oracle or using OpenJDK.

Find a "javaws.exe" that is installed under "(jdk|jre)*/bin/javaws.exe" in a path that suggests it is some 1.8 version.

You can download the jnlp file and then use "open with" on windows.

To look for "javaws.exe" under windows, you can use the file explorer, open "C:\\Program Files" and use the search functionnality to look for "javaws.exe". It may take a while.

If you don not find an installtion, you need to install one. For instance https://www.oracle.com/java/technologies/downloads/#java8 or https://openjdk.org/projects/jdk8/.

Recent versions of Java will indicate that the BT747 is not signed because the method that was used to sign the software is considered too weak.

To sign the SW with a stronger signature, a new code signing certificate is needed. Also to run on more recent Java versions, the code likely needs updates. So using Java 1.8 is the best option.