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Page Flipping
Most good CPC games use the page-flipping technique in order to display sprites and/or scroll the playing area smoothly. In especial, two memory areas (instead of one) are reserved for the screen ram. In each frame, one of the two screens is displayed in turn, by using the hardware (CRTC). At the same time, the next frame is being drawn in the non-visible screen until the next frame fly back signal. Then, the same cycle continues on and on for (each) next frame.
The big advantage of this technique is that we can use a whole frame's machine-time for our code (with no animation problems that arrise when we alter screen ram at the same time the electron beam displays it on the monitor). On the other hand, page flipping eats up a lot of memory area (which is crucial especially for 64Kb machines).
Hardware Scrolling