From: jj4public@nospicedham.vfemail.net   
      
   On Fri, 13 Dec 2019 00:24:55 -0800, bilsch01 wrote:   
   > Ralf Brown RBIL int 10h mentions pages:   
   > ah=5 select active display page   
   > ah=0xe bh=page number   
   > RBIL Table 00010 has a column heading for display pages.   
   >   
   > I searched around and can't find definition or details about the pages.   
   > What are they? How does one page differ from another? In particular are   
   > there address ranges associated with the pages?   
   >   
   > TIA.   Bill S.   
      
   Video page is basically a division of the video memory of the current video   
   mode.   
      
   For example, in 80x25 color text mode 03h, the used video memory is at   
   B800:0000 to B800:7FFFF or at linear address 0xB8000 to 0xBFFFF, fot a total   
   of 32KB.   
      
   Each video page size for that video mode is 4096 bytes. Video page index 0   
   is at 0xB8000-0xB8FFF, index 1 is at 0xB9000-0xB9FFF, and so on and up to   
   the last index 7 at 0xBF000-0xBFFFF.   
      
   The 80x25 screen only uses 80x25x2 bytes or 4000 bytes or 0xFA0 bytes. So,   
   there's actually 96 bytes of unused memory at the end of each video page.   
      
   Video page for other video mode has the same concept, but with different   
   size of video page because the memory needed for a specific video mode   
   differs. e.g. 40x25 text would have 16 video pages. 320x200 16 color graphic   
   video mode would have 2 video pages, because it needs 32000 bytes. i.e. at   
   A0000-A7FFF and A8000-AFFFF. 640x200 16 color video mode would only have 1   
   video page because it needs 64000 bytes of memory. The remaining 1536 bytes   
   of A0000-AFFFF memory is not enough for another video page.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)