I have a system which has a multi-pin control port normally connected to ordinary hardware push buttons: connecting 5V pin of that port to this or that other pin causes the device to do something.
I want to emulate keyboard presses in an old C64 microcomputer using an Arduino.
2. When I want to simulate the press of a single key, for example "A": 3. When I want to simulate the press of a combination of keys, for example "Ctrl+A":