With software piracy rampant throughout schools playgrounds, games companies were trying to find ways to give software more protection against this.

Software Projects were determined to not let their new smash hit game Jet Set Willy be copied so easily, as anyone who had a tape to tape machine in their homes could produce new copies.

Inside the cassette case was a piece of highly coloured card, produced in conjunction with Padlock Systems.

On it were numbers and letters that corresponded with a row of four colours. The player upon loading the game would be presented with a number, and using the card, had to match that number to four colours on screen, for instance A1 would need the player to input Blue, Purple, Green, Blue, getting the code correct would start the game. If the incorrect colours were input, the process would just continue to loop.

Unfortunately, there were draw backs to the system, a good few people trying to use the card were colour blind, so simply could not use it. A worse problem for the early Spectrum release were the instructions were wrong, misleading the player into inputing the codes wrong.

The card was also very small, as it had to fit inside a single cassette case, making reading it difficult for some.