HP LP2065 An Overview of Current Display Interfaces - Page 4

VGA The VGA connector - named for the Video Graphics Array standard introduced by IBM for the original Personal Computer products in 1987 has been the most successful PC monitor interface to date in the computer industry. In use now for over 20 years, the VGA (also known as the 15HD connector, for15-pin high-density Dsubminiature) remains the standard analog video interface of the PC industry, but is beginning to experience limitations. The D-subminiature connector family from which this connector was originally selected was never intended to handle very-high-frequency video, and VGA connections can often show the effects of low bandwidth, overall signal loss, and "ghosting" from impedance mismatches in the system. The use of cable extenders and switches often introduces additional problems of this nature. The popularity of the VGA connector continues primarily because it is inexpensive and has an enormous installed base - and the latter is not a minor concern as the industry tries to transition to newer, more capable interfaces. The analog section of the DVI-I standard carries VGA-compatible video, can interoperate with this standard, and will typically provide far better video performance, particularly for video timings and formats over 1280 x 1024 resolution. However, fully-digital interfaces (currently DVI-D or the digital section of DVI-I, but soon changing to the DisplayPort interface in PC applications and HDMI for TV/CE products) are the most probable long-term solutions. Figure 1 VGA Connector 4