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DVI
DVI (Digital Visual Interface) is based on transmitted minimized differential signals (TMDS). This means that in one cable wire the voltage can vary from a higher to a lower level.Here, it is essential to have a contrary voltage in another wire of that same cable. So when the voltage is lower in one wire, it needs to be higher in the other cable. The balance between these wires one pair) upgrades speed and quality.
DVI types
There are multiple DVI connector types:
 | DVI-D single link (18+1) - only digital signals |
 | DVI-D dual link (24+1) - only digital signals |
 | DVI-A (12+5) - only analogue signals |
 | DVI-I single link (18+5) - digital and analogue signals |
 | DVI-I dual link (24+5) - digital and analogue signals |
Two types of DVI-D and DVI-I
There are two different types of DVI-D and DVI-I connectors: a dual link and a single link connector. The difference between these two is the fact that the dual link can process higher refresh rates and resolutions than the single link. Dual link cables can be used instead of single link cables; however, several brands do not provide opening of all openings of the frame (as with the former VGA pin 9).
Please view the differences in the table below:
Refresh rate | Resolution Single Link | Resolution Dual Link |
| 60-Hz LCD 1920 x 1080 (HDTV) | 75-Hz CRT 1280 x 1024 (SXGA) | 85-Hz CRT 1280 x 1024 (SXGA) |
| 2048 x 1536 (QXGA) | 2048 x 1536 (QXGA) | 1920 x 1080 (HDTV) |
The difference between DVI-D and DVI-A connectors is obvious: the DVI-D connector only transfers digital signals whereas the DVI-A connector transfers only analogue signals. The DVI-I connector can transfer both analogue as digital signals. So the DVI-I connector can be used for both DVI-A and DVI-D connectors (when all openings on the frame are open).
High Quality Cables | Standard Quality Cables |
| Cables are certified by DVI Digital Working Group | Cables are not certified by DVI Digital Working Group |
| Cables have two ferrite cores | Cables do not have ferrite cores |
| Die-cast aluminium shielding hoods | Foil shielding |
The Digital Display Working Group is an industrial group lead by Intel, Compaq, Fujitsu, Hewlet Packard, IBM, Nec en Silicon Image (see www.ddwg.org).
