Slightly off topic: One day in the late 90s or early 2000s, I wanted to transfer the contents of my Atari 8-bit disks to my PC. I did know about SIO2PC, a cable that converts between Atari's SIO port and the PC's serial port and a piece of software to go with it. But I didn't have the electronics skills to build one (even though it is actually very easy). So I ended up writing a Basic program on the Atari to read dat…
Reminds me of how the first generation iPod firmware and keys were reverse engineered. They blinked out bit patterns on the LCD backlight and used a camera to read the data in! https://mastodon.social/@bagder/111538350617290554
Citation needed, but I think I read that hackers dumped the firmware of Canon cameras by blinking the single red LED on the camera (and foregoing the main graphical LCD). See the CHDK and Magic Lantern projects.