In article , "Jim Maricondo" writes: >See my web page at www.maricondo.org. Very nice description, Jim, and fine photo documentation of the results. ;-) I note that the major problem you encountered was video "jitter" (random 1-pixel horizontal shifts of video features). This happens whenever the producer and consumer of a digitally generated video signal operate on unsynchronized clocks. If both the producer and the consumer agree about the number of horizontal pixels, then a good phase-locked loop can lock to the pixel positions and recover them stably. But if they do not agree, then such pixel lock is not possible, and there will be (at least) regions where a producer pixel is randomly assigned to one of two adjacent consumer pixels. In your setup, you have two pairs of producers and consumers: first, the IIgs and the scan doubler, and second, the scan doubler and the LCD. The fact that the scan doubler menus exhibit jittery edges on the LCD suggests that, whatever is going on between the IIgs and the scan doubler, there is a pixel clock asynchrony between the scan doubler and the LCD. Since the LCD presumably is designed for VGA pixel counts, and the scan doubler is designed to produce them, this is surprising. Assuming that the LCD acts properly when driven by a VGA card at the same scan rates and resolution, then the fault must be in the scan doubler video generator. Perhaps there is jitter in the horizontal sync, or even in the horizontal period. An oscilloscope could be used to verify that the scan doubler output (of its own internally generated menus) is stable and of the correct pixel count. Assuming that this is corrected, there is still the issue of the first producer-consumer pair, the IIgs and the scan doubler. Here the problems are more fundamental. There is no "standard" for how many pixels are in an analog NTSC horizontal line, but the digital TV standard sets it at 640 pixels (in the time between the end of one horizontal blanking pulse and the beginning of the next). The IIgs certainly does not meet the dot rate "standard" for digital NTSC. This means that there are always going to be pixels generated by the IIgs which fall ambiguously between "standard" pixel positions, and this situation will often result in a jittery "assignment" of the pixel transition to one or the other of the "standard" pixels. When the internal scan doubler buffer is read out at VGA rates, it will reflect the jittery assignment of the IIgs pixels as they were digitized. It may be possible to "lock" the dot clocks of the IIgs and the scan doubler digitizer to some fairly simple harmonic relationship (like 157:135, or some such ridiculous ratio) using simple analog coupling of the clocks (!), but, at root, there is a pixel enumeration problem which will continue to produce artifacts. For example, some of the IIgs pixels will have to control _two_ adjacent VGA pixels in some cases, since 560 is less than 640, and (of course) does not evenly divide it. This will produce irregularities (banding) in "halftone pattern" IIgs screens, and, of course, some vertical lines will appear to be twice as wide as on the IIgs screen. If you were displaying on an analog CRT, then the scan doubler-to-LCD issue would not exist, and the scan doubler's own menus should be stable. But this would still not address the issues of digitizing the IIgs video with an asynchronous dot clock. The underlying issue could be addressed by digitizing the IIgs video _only_ between its blanking pulses (a shorter line) with exactly 560 pixels, and phase locking the digitizer to the video. But this is likely only with either a very specialized IIgs scan doubler (a labor of love because of the small market) or a very general professional scan converter which can be customized to virtually any input (and with a professional pricetag). Truly, an unfortunate situation. ;-( Does anyone know if the Apple Video Overlay Card outputs its pixels in the "middle 560" of a 640-pixel digital NTSC line? If so, then its output should be able to be stably "scan doubled" by non- professional equipment. -michael Check out amazing quality 8-bit Apple sound on my Home page: http://members.aol.com/MJMahon/