The program recognizes when a tone generator with a Morse code key is connected to the sound card.
A problem are newer, simple laptops that have a built-in microphone but often no longer have a seperate microphone input at all. For this, there are external sound cards for connection to a USB interface (e.g. USB sound card from UGREEN for 14.00 euros on Amazon (Amazon Germany as of March 2021)).
You also need a tone generator to which the Morse code key can be connected. For example, on the market there are keys for beginners with a connected tone generator.
The “Ear Phone” output of the key respectively the tone generator is connected to the microphone input of the sound card with a jack plug. The volume and pitch can be adjusted with the controls. A 9 volt block battery is used as the voltage source, but the device can also be operated with a power supply unit.
If you don’t want to work with a simple beginners key (in my experience the lever arm is a bit too flexible when keying), a better key can be connected to it. In the next picture you can see a K-64 (GDR), which was connected to the tone generator with alligator clips. You can do this to try it out, but later you should not only connect the second button provisionally.