There was a time in the early 1980s when one could find ads for many different unauthorized Apple II clones in the back of just about any computer magazine. The ads promised inexpensive reverse-engineered copies of the Apple II computer hardware designed to use Apple II software and peripherals. Apple wasn't too happy about the illicit machines and even managed to win some import bans on them in the US, but many remained on the market.
Some folks, like my father, even bought underground replicas of the Apple II motherboard, copied the Apple ROMs onto EPROMs, and built their own Apple IIs from scratch. It was a lot cheaper than buying directly from Apple, so many people with the technical know-how chose that path.
Discussion Topic of the Week: Have you ever owned or built an unauthorized Apple II clone? Tell us about it.