Post by thread:[TLUG]: XF86 config needed

>Also could someone explain how LCD screens deal with vertical and >horizontal sync. Electrically speaking, the LCD is a very large shift register. Data is clocked in by something called pixel clock. This is known as the dot clock in X11 config files. The data clocked in is analog RGB information on three distinct channels, called R, G, B usually. The shift registers in the LCD have a certain length and when a line is full, then the register needs to be transferred to other (vertical) shift registers.There are as many vertical shift registers as there are horizontal pixels in the LCD. The time to do this is when the horizontal sync pulse is coming from the video display hardware. Similarily, the vertical shift registers in the LCD eventually fill up, and then a the vertical sync pulse is used to actually move the contents of all of the vertical shift registers into the byte cells, where they eventually affect the display (it is not affected while all the shifting and clocking happens). The blanking period is important because the moving of the contents of the shift registers requires a certain amount of time and special timing (achieved by a controller chip or firmware). Too short = artifacts, too long = flicker in the display. However, there is no rule, anything could happen. hope this helps, Peter PS: The explanation above is valid for large (>512x256) displays with serial addressing. Smaller displays may use direct XY matrix (not serial) pixel addressing (examples: cellular phone, PDA). -- http://www.piclist.com hint: To leave the PICList spam_OUTpiclist-unsubscribe-requestTakeThisOuTmitvma.mit.edu