AMOS:Working with bitplanes

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(this is a work-in-progress tutorial and has not been tested yet!!!!!)

Amiga uses bitplanes, so instead of using one or more bytes per pixel, the screen exists of several layers (bitplanes) in which each byte contains 8 pixels. For every bitplane added the maximum amount of colors doubles:

• 2^1 = 2 = 2 colors
• 2^2 = 2*2 = 4 colors
• 2^3 = 2*2*2 = 8 colors
• 2^4 = 2*2*2*2 = 16 colors
• 2^5 = 2*2*2*2*2 = 32 colors
• 2^6 = 2*2*2*2*2*2 = 64 colors

If you want to know how many bytes a line takes in a bitplane use this formula:

size of one line within a bitplane ScreenWidth / 8 ScreenWidth / 8 * ScreenHeight ScreenWidth / 8 * ScreenHeight * AmountOfBitplanes

So say you want to copy a bitplane from an AMOS screen to an AMOS bank:

```BitplaneSize = Screen Width / 8 * Screen Height Reserve As Work 10,BitplaneSize Copy Phybase(0),Phybase(0)+BitplaneSize To Start(10) Wsave "RAM:Bitplane",10 ```