Re: no box sprites

 BBS: Inland Empire Archive
Date: 07-14-92 (01:05)             Number: 245
From: MATT PRITCHARD @ 930/21      Refer#: NONE
  To: JON SPRINGER                  Recvd: NO  
Subj: Re: no box sprites             Conf: (2) Quik_Bas
JS>Ok, thanks, hope you get the code up.  I'm you know of any
JS>way to flip screens in mode 13h through native qb?  I know most
JS>vga adapters have enough memory to handle more than one screen,
JS>which is what basic provides...

To do multiple screen pages in mode 13h, you pretty much have to switch it
over into the 320 x 200 variant of Mode "X".  in Mode 13h,
(QB 13 decimal), read an writes to the VGA memory at
A000:xxxx are actually being translated by the hardware.
The upper 14 bits are shifted down 2 bits to get the actual
addres, while the lower 2 bits are the memory plane #.  You
may poke from 0 to 63999, but you actually have poked from
0 to 15999, planes 0 through 3.  You just can't get to the
other 192K of video memory without altering the control
registers a good deal, and then you can't read/write to it
like you can in in nommal mode 13h. You have to use the
mode X techniques.

-Matt P

 * SLMR 2.1a * My reality check just bounced.

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