This reminds me of a hack that my colleague used to extract data from an "airgapped" device. The device was a computer that had a broken Ethernet card. It wasn'

This reminds me of a hack that my colleague used to extract data from an "airgapped" device. The device was a computer that had a broken Ethernet card. It wasn't able to send packets but could jam the other cards connected to the Ethernet segment (coax Ethernet - all cards in the local network were galvanically connected to the same wire). So he wrote a piece of code to transmit bits via the "jammed" and "unjammed" states. This was on DOS, so it was easier due to all the hardware being directly available without OS getting in the way.