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Man-in-the-Middle PCB Unlocks HP Ink Cartridges
(hackaday.com)
This is a most excellent place for technology news and articles.
My HP printer is 15 years old and we are not changing it until it breaks.
We are used to refill cartridges with a ink syringe.
Dad is that you? :D
Unfortunately he bought a "modern" HP a few years back. It's a nightmare.