Sky have used the Synamedia (formely NDS and Cisco) VideoGuard encryption system since 1998. Here are some of the viewing cards used for it.
This was a prototype viewing card. However, this may be ambiguous as we don't know if it means 'digital viewing' card or 'digital' viewing card. In contrast to this, there are no other sources or images of this card, meaning this could support our argument.
Also known as the Egg Logo Card, this was the first viewing card for Sky Digital issued at launch in October 1998.
Also known as the Swoosh Logo Card, this was the second viewing card for Sky Digital first issued in 1999 when Sky changed their logo to the Helvetica Logo (aka Swoosh Logo). The reason why this still has the same Period 1 name as the previous card, is because the internal of the card has the exact same specification; the only difference is the design on the print.
Also known as the Yellow House Card, this was the third viewing card issued by Sky starting from sometime in 2003. There were various "viewing card exchange" promos in TV ad breaks to alert customers of the changes.
In 2009, Sky issued a brand new viewing card to all subscribers, known as the 'white card'. This card aimed to fix a number of security loopholes, such as requiring a periodic activation signal from satellite.
This viewing card was sent to customers who required new ones in mid 2015. It was mostly issued to customers who had recently installed Sky Q, after launching on 9th February 2016.
The sixth and latest viewing card for the Sky Digital service, now being issued to new and existing customers.
During an active card swap, the following takes place when a user replaces their viewing card.
User removes their old viewing card
User inserts their new viewing card
OSM displayed - 'Card changeover in progress'
During this stage, the new viewing card is activated, and a value is written to the box's EEPROM memory, which disallows any previous period cards to be used. For example, if you would insert a period 2 card, you would receive the OSM 'Insert your new Sky viewing card'.
OSM displayed - 'Card changeover is complete'
As of 2021, inserting a newer issue viewing card into a box currently does not write to the EEPROM memory, thus not locking out older cards.