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I'm building a small bootloader for x86 as a project. For the moment I'm writing several functions to handle the screen, since it's a bit tedious. Most BIOS interrupt functions involve a page number argument, and I can't tell what this is for. Wikipedia hasn't nothing to say, I think.

Does anyone know what the page number represents?

Thanks

Guido
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2 Answers2

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There's enough video memory to allow multiple text screens side-by-side. The page numbers allow you to do double-buffering, where you draw to an off-screen page, and then when it's ready change the currently visible page to the new one.

See the infamous and still invaluable Ralph Brown's Interrupt List for more (well, a little more) information:

http://www.ctyme.com/intr/rb-0087.htm

In particular, look at int 0x10 AH=0x05, which lets you change the current visible page.

David Given
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    _There's enough video memory to allow multiple text screens_ ← depending on the video mode, but otherwise good answer. – ninjalj Mar 06 '12 at 21:45
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Just use page 0, which is the default current page.

Alexey Frunze
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