In computer terminology, a "Dog" is slang for a . Before cloud subscriptions and online license servers, software companies used physical hardware locks to prevent piracy.

, colloquially known in some regions as a "dog" (from the term "watchdog"). To make these devices functional, a specific software component—the parallel port dog driver —was essential. The Role of the Hardware Dongle

Data bit 0 → dongle input Dongle output → Status bit BUSY (pin 11)

The parallel port was originally designed for one-way communication: sending data to a printer. However, dongles needed to send data back to the computer to verify the license. This required a specific software layer known as a .