The device is a few inches long, rectangular, with two folding hinges on either side supporting a specially engineered prism-like lens. At certain points in the game the user can go no further until he holds it over some strange on-screen blotches, which become miraculously readable when viewed through the special lenses of the device. Type in the now-visible code and the player can continue. Surely this is pushing way past the limits of acceptable DRM?
Thankfully, Lenslok isn’t the latest horrible idea in anti-piracy technology – in fact, it was first introduced more than 20 years ago. Developed by inventor John Frost, the device had a lens which carried around a dozen grooves which sent light though it at varying angles, ‘unscrambling’ seemingly random graphical blocks underneath it to reveal a secret ‘continue’ code. 
These days, DRM is often applied a little more stealthily but never has it been as complex for the legitimate user as it was with Lenslok.
Rather than explain the full process of using the Lenslok, here is a scan of the original instructions that came with the device:
The first game to use the Lenslok DRM was the ZX Spectrum version of the hugely successful wireframe-3D shoot ’em up, ‘Elite‘. But of course, we’re talking about DRM here so yes, you guessed it, it caused lots of problems for the legitimate users. As each version of the Lenslok device was unique to the game it sought to protect, sending out the incorrect Lenslok device to around 500 buyers of ‘Elite’ wasn’t the best move made by the publisher, ‘Firebird‘. None of these people could play the game, but probably had an interesting experience for a few hours trying to work out how to use the prism. With no Internet forums to voice their anger, there were many complaints in the computer magazines of the day.
The final nail in the Lenslok coffin was its inability to work with anything other than a tiny portable TV, as the on-screen input window would otherwise be bigger than the device itself, rendering it useless.
Although Lenslok is now (thankfully) dead and buried, those people running a ZX Spectrum emulator might still come across its evil work when playing games such as ACE, Art Studio, Elite, Jewels of Darkness, Price of Magik, Tomahawk or TT Racer.
So, the choice is to either pick up a Lenslok off eBay for next to nothing, or run a digital emulation of it – a sure sign of the times.
