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   comp.sys.cbm      Discussion about Commodore micros      53,866 messages   

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   Message 53,082 of 53,866   
   PaulM to All   
   C-128 Smooth Scrolling in 8563/80-column   
   01 Jun 20 13:26:14   
   
   From: paul.s.macmillan@gmail.com   
      
   Hi,    
      
   I have been playing around in a VICE x128 app, trying my luck at the 8563   
   smooth scrolling features.   
      
   I know that writing values 1-7 to Register 24 causes the display to scroll the   
   intended number of scan lines, and I see that working (sort of). While the   
   content gracefully slides up and out of view at the top, what appears at the   
   bottom of the screen,    
   the new content to be scrolled in, appears as "gibberish."   
      
   I am using the $1000 area of 8563/video RAM as the character display RAM (set   
   via registers 12 and 13) and have written/copied 2 entire screens worth (4096   
   bytes) of blank screen characters (#102) to fill the RAM before I try   
   scrolling.  But no matter    
   what the new data scrolling in at the bottom is garbled. I have advanced   
   Register 13 (low byte of screen data) by 80 bytes before and after the   
   attempted smooth scroll to no avail.   
      
   Any clues appreciated!   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)   

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