The video player: Bandwidth

The amount of changes from one frame to another may also exceed the amount that the renderer can handle within those 4 frames, especially if the various pixels are disjoint.

In the Go Figure intro, ignoring the “invert the palette”-trick, the highest number of pixels changed in one diff is 21 725 from a maximum of 49 152 (256 x 192 pixels). That includes VDP commands. Maximum VDP I/O seems to be around 10 000 pixels or 20% of the visible screen.

These numbers are measured while the target cycle cost per frame was set just below 50 000 to allow for music and other overhead in the game. With more time allotted per frame, for example by using a low cost PSG player, or targeting PAL, we could get better numbers.

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