Lenslok

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Lenslok lens (below) with cassette for size comparison

Lenslok was a game software copy protection system that was used in home computers such as the Commodore 64 , Sinclair ZX Spectrum and Schneider / Amstrad CPC in the 1980s . The best-known software in which this copy protection was used is the game Elite for the ZX Spectrum. The Lenslok system consisted of a small, clear plastic lens on which a number of small prisms were stamped vertically. It was thus a hardware copy protection.

Before a game could be started with this copy protection, the software asked the player to hold the lens in front of the monitor in order to enter two letters that were displayed on the monitor but could only be read correctly through the lens in a corresponding input field . The lens was small enough to be shipped in the case of a compact cassette . At that time, compact cassettes were one of the most common media used to distribute computer games. In order to be able to recognize the letters, the monitor or television on which the game was displayed had to be calibrated accordingly, which did not work to the required extent with all devices. Like many copy protection systems of the time, the process was easy to bypass: gamers who knew machine language could find the code in the computer's memory, especially if one looked for the instruction text on the Lenslok screen in the binary code of the program. These circumstances and the great effort for the user meant that the system was very reluctantly accepted by the market and ultimately did not catch on.

Software with the Lenslok system (selection)

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