USB to 2x20 pin GPIO (like Raspberry Pi have) should be easy. Found this: "Ryanteck RTk.GPIO (PC GPIO Interface)" https://uk.pi-supply.com/products/ryanteck-r

USB to 2x20 pin GPIO (like Raspberry Pi have) should be easy. Found this: "Ryanteck RTk.GPIO (PC GPIO Interface)" https://uk.pi-supply.com/products/ryanteck-rtk-gpio-pc-gpio-interface https://uk.pi-supply.com/products/ryanteck-rtk-gpio-pc-gpio-... gpiozero > Remote GPIO: https://gpiozero.readthedocs.io/en/stable/remote_gpio.html https://gpiozero.readthedocs.io/en/stable/remote_gpio.html : > GPIO Zero supports a number of different pin implementations (low-level pin libraries which deal with the GPIO pins directly). By default, the RPi.GPIO library is used (assuming it is installed on your system), but you can optionally specify one to use. For more information, see the API - Pins documentation page. > One of the pin libraries supported, pigpio, provides the ability to control GPIO pins remotely over the network, which means you can use GPIO Zero to control devices connected to a Raspberry Pi on the network. You can do this from another Raspberry Pi, or even from a PC. Presumably, e.g. TLS to secure that control channel is your responsibility. Parallel ports > Pinouts: https://en.wikipedia.org/wiki/Parallel_port#Pinouts https://en.wikipedia.org/wiki/Parallel_port#Pinouts "The parallel port" (2023) https://news.ycombinator.com/item?id=34585216 https://news.ycombinator.com/item?id=34585216 Serial port: https://en.wikipedia.org/wiki/Serial_port https://en.wikipedia.org/wiki/Serial_port UART: Universal asynchronous receiver-transmitter: Serial TTL: https://en.wikipedia.org/wiki/Transistor%E2%80%93transistor_logic#Serial_signaling https://en.wikipedia.org/wiki/Transistor%E2%80%93transistor_... : > TTL serial refers to single-ended serial communication using raw transistor voltage levels: "low" for 0 and "high" for 1. [31] UART over TTL serial is a common debug interface for embedded devices. "Possible to use a 9 Pin Serial port as "GPIO" using ioctl()?" https://stackoverflow.com/questions/27789099/possible-to-use-a-9-pin-serial-port-as-gpio-using-ioctl https://stackoverflow.com/questions/27789099/possible-to-use... D-subminiature > Typical applications > Communications ports: https://en.wikipedia.org/wiki/D-subminiature#Communications_ports https://en.wikipedia.org/wiki/D-subminiature#Communications_... Crosstalk: https://en.wikipedia.org/wiki/Crosstalk https://en.wikipedia.org/wiki/Crosstalk "Can you hotwire this computer to transmit a tone through the radio?" https://www.getyarn.io/yarn-clip/aac07d77-c6d6-4da7-bdd3-b93de8ea229d/gif https://www.getyarn.io/yarn-clip/aac07d77-c6d6-4da7-bdd3-b93... https://en.wikipedia.org/wiki/Air-gap_malware https://en.wikipedia.org/wiki/Air-gap_malware