Re: NES - Apple Sprite card

[mjmahon@aol.com (Michael J. Mahon)]

Roy replied:

>Yves McDonald wrote:
>> Right on, I have the sprite card at home but never tried it.  It was 
>> designed by Steve Ciarcia and introduced in the late Byte magazine. 
>> Resolution was inferior to Apple's high res mode (256 horizontal pixels 
>> vs 280) but it definitely had more colors (up to 16).  All you could 
>> program were sprites of 8x8 or 16x16 pixel resolution.  To build an 
>> image such as game backdrop, you have to 'tile' sprites.
>
>I'm not sure exactly what you mean by "tile".
>The 9918/28 VDP had 32 different "layers" that were "stacked" one on top 
>of another. A single sprite only could be on a layer. The result was you 
>could "paint" a scene on the lowest "layer" and various sprites moving 
>about so that you had a 3D effect (a sprite shaped like a plane would 
>move "behind" a sprite shaped like a cloud, or in front of another "cloud

What Yves is referring to is that there is no "pixel-mapped" layer.
The background layer is made up of 8x8 or 16x16 "characters"
or "tiles" which are mapped into the display space (where visible).

This intermediate "character mapping" is a bit of a mess for doing
simple 2D graphics, since new "characters" have to be created
almost anytime the image is changed.  Of course, sprites are
hardware-implemented, so moving sprites do not require a change
to the background.  But plotting a line would.

-michael

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