a quick copy / paste from wiki, it mainly speaks about TV sets, but, highlights the differences between 'a CI slot' and 'CI+'
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CI+
CI Plus or Common Interface Plus implements a form of copy protection between a Conditional Access Module (CAM) and the television receiver (Host). CI+ is backward compatible with CIv1. Old television receivers, which have CIv1 CI-slot, can be used with CI+ CAM and vice versa, but for viewing only those of TV programs which are not marked as CI+ protected.
Definition
CI+ is a specification that extends the Common Interface as found in the digital broadcasting standard. It has been developed by consumer electronic firms Panasonic, Philips, Samsung and Sony, as well as pay-TV technology company SmarDTV and fabless chip maker Neotion.[1]
A first draft of the specification was put up for review early in 2008. The final version was released at the end of May 2008.
By making use of certificates and a certification authority, a trusted channel is formed between the CAM and television receiver (Host), when scrambled content is being received. In the original CI standard, decrypted content could be sent over the PCMCIA interface unscrambled. The establishment of the Trusted Authority has been completed[2] and an official security certification lab appointed.[3] With the development of CI+, the standard has now come under the umbrella of the DVB standards organisation.[4]
A CI+ compliant Host device must also implement MHEG-5 interactive TV engine to manage navigation of the user within an interactive TV application, using its device remote control.[5] Support of MHP or HbbTV interactive TV engines is optional.
Operators
The following operators have currently rolled out CI+ support or plan to do so:
France
Canal+ – launched the "Canal Ready" label for devices able to receive Canal+ channel
Germany
Kabel Deutschland – NDS conditional access and SMiT CAM modules will be used
Netherlands
Caiway – launched CI+ in October 2009[6][7]
Delta – launched CI+ in 2010
Kabel Noord – launched CI+ in 2010
UPC Netherlands – launched CI+ in 2011
Ziggo – launched CI+ in September 2009, SMiT and Neotion CAM modules are used[8]
Sweden
Boxer
Com Hem
Switzerland
Cablecom (UPC Broadband) – Starting June 2010[9]
Italy
Mediaset Premium (Digital terrestrial television) - needs CI+ slot on HD television to descramble High Definition channel Premium Calcio HD. No CI+ cams have been sold so far (the only way to receive this channel is to buy an external decoder with HDMI cable).
Romania
UPC Romania - Starting April 2012
Turkey
Teledünya
United Kingdom
Top Up TV[10]
In July 2009 the largest Cable operator in the Netherlands, Ziggo, announced that it will support CI+ based Integrated Digital Television sets (IDTVs) actively.[11][12][13] In September 2009 the first batch of 15,000 SMiT (Shenzhen State Micro Technology Co., Ltd.) CI+ CAMs was offered by various Dutch retailers, followed in October 2009 by the first batch of Neotion CAMs.[14] Other supporters include Canal+,[15] and conditional access companies Irdeto[16] and Conax.[17] NDS announced that it will support Kabel Deutschland to deploy CI+ to its customers.[18]
Compatible TV Sets
LG 2010 models all LD and LE series also MFT models MXX80D.
Many of Samsung's new LCD, LCD LED and Plasma model variants with CI+ compatible motherboards.
Many of Sony's new models including the Bravia W5500 series.
Philips new 5000 and 9000 series LCD TVs (required firmware pending according to Ziggo).
Some Panasonic models. It seems that even products with CI+ slots need a new firmware to be fully CI+ compatible. (Update 2010)