All analogue windowing architectures multiplex graphics and video as analogue signals rather than as digital information, but they vary widely in signal manipulation and digital processing capabilities. While they do offer some advantages, analogue architectures fail to address certain problems. For example, the graphics pixel-clock frequency becomes the pixel clock for the video image. Therefore, the greater screen resolution, the smaller the video window. Since enlarging the image means losing graphics resolution, the end user may find himself changing display drivers several times a day to fit the immediate task. The simplest analogue architecture is the genlocked video overlay. Composite video is decoded into its RGB components. Having no control over the video source, the graphics controller must be genlocked to the video source, operating at a resolution and timing characteristic compatible with the incoming video signal. The graphics signal is switched in and out at appropriate times so that the graphic appears in the desired place in the image. The multiplexed output is then encoded into a new composite signal. The analogue multiplexer, currently the most popular architecture, is actually a group of slightly varied architectures. The most popular variation imports the graphics data and pixel clock from the graphics card feature connector across a ribbon cable, where it is fed to a DAC.

The video signal is digitized, color-converted, and scaled, then is stored in a frame buffer similar to a FIFO which synchronises the data. When the video data emerges from the frame buffer, it is fed to a second DAC. The two DACs are connected to an analogue multiplexer that is controlled by a set of counters that keep track of the beam position on the graphics display.

When the beam enters the video-window area, the mux is switched from the graphics signal to the video signal.