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Atari ST color question


retrogeek

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I'm working on a few projects for the Atari ST line of computers. I have experience in basic, some assembler, C, and have coded small projects for the Commodore 64, Amiga, and PC but have never fully developed anything on the ST. I am aware of the ST's limited color palette and have some questions about coding graphics and sprites for the system. I've done searches on the Internet to try and answer these questions on my own, but I've come up empty-handed. I was lucky enough to find a few ST coding guides on Amazon.com but they're taking forever to arrive.

 

I'm wondering if the Atari ST can allocate a palette of 16 colors per screen or is it limited to what you initially choose for development? For example: during Amiga development you could allocate different pallets per screen, so basically you could have multiple colors that wouldn't clash when, say, screen 1 uses a color palette different than screen 2. Also for sprite development: will all sprites borrow from the same color registers? I hate to ask such novice questions but I haven't developed such a large project on an Atari computer.

Edited by retrogeek
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It has been a long time since I have thought about the ST -- but here is what I remember. There were 3 main graphics modes:

1) Monochrome (only worked if you had a monochrome monitor, if I remember correctly)

2) 4-color mode "Medium Rez" (640x200?)

3) 16-color mode (320x200)

 

Pretty much all games and applications ran in the 16 color 320x200 mode; In 16 color mode, you could choose from a palette of 512 different colors -- unless you were lucky enough to get an STE, in which case you were able to select from 4096. There were some tricks you could pull (for instance, Spectrum 512, an art program from Antic mag did this) that increased the number of colors on screen at a time -- but due to the processing power required, you really couldn't do anything aside from a static picture.

 

"Sprites" use the same color palette as the main screen (the ST didn't really have separate sprites, everything was done in software -- again, unless you had the STE and a "blitter chip" -- but this only sped up the copying of memory -- it didn't increase the number of available colors on screen)

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It has been a long time since I have thought about the ST -- but here is what I remember. There were 3 main graphics modes:

1) Monochrome (only worked if you had a monochrome monitor, if I remember correctly)

2) 4-color mode "Medium Rez" (640x200?)

3) 16-color mode (320x200)

 

Pretty much all games and applications ran in the 16 color 320x200 mode; In 16 color mode, you could choose from a palette of 512 different colors -- unless you were lucky enough to get an STE, in which case you were able to select from 4096. There were some tricks you could pull (for instance, Spectrum 512, an art program from Antic mag did this) that increased the number of colors on screen at a time -- but due to the processing power required, you really couldn't do anything aside from a static picture.

 

"Sprites" use the same color palette as the main screen (the ST didn't really have separate sprites, everything was done in software -- again, unless you had the STE and a "blitter chip" -- but this only sped up the copying of memory -- it didn't increase the number of available colors on screen)

 

 

Thank you for responding! The information in your post has given me a better understanding of what needs to be done. I'll look around for an STE for future development purposes.

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There are no sprites.

 

You do software sprites, which means bitmap objects using normal palette colours.

 

 

There are 16 palette registers. Background and border share the same colour register, although you can get around that by using a foreground colour as fill.

 

You can simply reload the palette registers between "screens", but still you have that 16 colour limit.

 

 

But, of course games, demos and some picture/paint programs use interrupts and other tricks to get more than 16 colours onscreen.

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