Path: utzoo!utgpu!attcan!uunet!husc6!cmcl2!nrl-cmf!mailrus!cornell!uw-beaver!tektronix!tekig5!wayneck
From: wayneck@tekig5.PEN.TEK.COM (Wayne Knapp)
Newsgroups: comp.sys.atari.st
Subject: Re: Questions about ST Video Ram
Summary: kkk
Message-ID: <3090@tekig5.PEN.TEK.COM>
Date: 3 Aug 88 18:01:02 GMT
References: <535@skywest.UUCP>
Organization: Tektronix Inc., Beaverton, Or.
Lines: 28

In article <535@skywest.UUCP>, brenes@skywest.UUCP (Erasmo Brenes) writes:
> to allocate 64Kb and then only use the 32Kb which start in a 32Kb boundary,
> but this method is too wasteful. There's got to be a better way, isn't there?
> 

Actually, I think you need to allocate the screen on 512 byte boundry.  The
reason for this if the shifter is missing the lower nine bits of it's 
screen base pointer.  (It could be 8 bits and 256 byte boundry)  Anyway
try this.

    unsigned char  screen[32512]; 

    long  scrtemp;
    unsigned char *scrptr; 

    {
      ...
        scrtemp = (long) screen;
        scrtemp &= 0xfffe0000L;
        scrptr = (unsigned char *) scrtemp;
      ...
        Setscreen(scrptr,scrptr,0)  /* set screen to low resolution */
      ...
   } 

   Maybe not 100% correct but I sure it is closer to what you want.

                                      Wayne Knapp