Michael J. Mahon wrote:
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 "cloudWhat 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).
My manual on the 9918 is out on loan at the moment, but I thought the lowest level was a pixel-mapped layer.
Certainly, if you did a graphic image in BASIC on either the TI or the Coleco, sprites were never used. The ADAM's BASIC had exactly the same commands as AppleSoft, so that any graphics work done in AppleSoft (that didn't use Peeks or Pokes of course) could be done on the ADAM.
Many a time I typed in Apple programs from Family Computing on my ADAM and had they look exactly the same as the picture of the Apple version. Or, if machine lanugage was used, the same program with different data statements.
Roy
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 Check out 8-bit Apple sound that will amaze you on my Home page: http://members.aol.com/MJMahon/
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