I was not planning on putting any Vic-20 stuff on here, but I found this one very interesting. It’s from 1984 and would copy a cartridge to a cassette tape. This used an adapter board that plugged into the expansion slot and software.
C64 Copy Protection
Documenting the History of the Commodore 64 protection scene
I had something similar in the UK called ‘Softswitch’
You used ‘POKE 38912’ with 1, 2, or 3 to move memory blocks around depending on whether 8K or 16K cartridge and disabled the write line to the RAM so overwrite protection did not corrupt the game.