re: digital display vs analog display -- ... Digital Flat Panel (DFP) initiative ... goal is eliminating all analog display circuitry between computers and flat panel monitors.
3, that was an interesting article. Here's what it's talking about.
CRT monitors use analog inputs. Analog signals are natural for CRTs: the signals are driving an amplifier which controls the intensity of the Red Green and Blue guns in a continuous manner. The cabling is cheap too: you need only 6 wires. This is what the VGA and later CRT's use.
For LCD's, the inputs are digital. If you see an analog input LCD it means you are paying for a triple analog to digital converter and some fancy sync hardware to generate the digital outputs. The signals started out as digital in the computer, so why go to the expense of an analog intermediate form? It makes sense if you are only driving CRT's. Otherwise it degrades the picture and costs extra.
For CRT displays, the Digital to Analog converter could be incorporated in the CRT monitor for the same cost as it is in the PC, so the system cost would remain essentially the same. Historical trivia: the EGA display that IBM shipped with the PC/AT had a digital interface, with two bits per color: (2^2)^3 = 64 colors!! Who could want anything more?
The technology to put 8 bits of color for three colors on a cable in digital form is relatively recent, within the last 3 years, so it wasn't available when the VGA came out. IBM made a good decision to put the ADC in the PC with the VGA, because you could have very good color at little cost.
I don't have current costs, but I would guess that eliminating the DAC from the PC would save about $10, and eliminating the ADC from the LCD monitor would save about $50. So the LCD system gets cheaper and the CRT system remains the same. And the user interface is much simpler, because those triple ADC monitors are hard to set up right. Everybody wins! Except that to drive existing analog CRT monitors you'd have to buy an outboard ADC, or continue using your old one.
Hope this is not too technical.
Stewart |
