Most devices intended to enable piracy on the VideoCrypt system had been based around programmable chips, some single-use which could not be reprogrammed, but even reprogrammable chips required the necessary equipment, software, and knowledge in order to alter their contents. This meant that any change that Sky made to the system to prevent piracy could not easily be avoided by a casual user of piracy devices.
How It Worked
Given the fact that pirate cards, whether viewing cards or intermediate devices designed to intercept communications, could not be easily reprogrammed by casual users, a solution was devised in the form of the “Battery Card”. The concept had been used in other regions for similar purposes, but the value it held for the European market had not yet been understood, being considerably more expensive than other cards already in use.
This type of card was similar in essence to the previous attempts at clone cards, however it had one important difference in that it could be reprogrammed without technical knowledge. It contained a Dallas microcontroller, as opposed to the Microchip PICs used in other cards, which had a battery-backed memory. In this memory it could hold data such as keys which could be entered using a series of buttons or button contacts similar to those found on the circuit board of a television remote control. This would enable the user to input new data if and when the VideoCrypt system underwent changes to mitigate piracy. Unlike alternatives, this battery-backed memory could be rewritten frequently and, with the provided button pads, trivially by an end user.
As legitimate viewing cards by this point employed an ASIC to make cards more difficult to clone, these battery cards required and contained emulations of them.
This differs in that PIC microcontrollers required code to be compiled and written to the chip by a programmer sufficiently educated in producing functional microcontroller projects and then written to the chip in its entirety using specialised equipment. This equipment was not particularly unusual or complex, but it did require understanding of how to use it, and of course it required a user to own one.
This simplification for the end user enabled numeric codes to be distributed via electronic means which could be typed into the device without special equipment, making it much faster, easier, and less expensive (than paying for a new card or a ROM to be rewritten) than the previous methods.