Re: GEMBOOT and GFA-BASIC

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Article #27713

#27713

From: XBR4D76H
Date: Thu, 23 Jul 1987 08:03

18 lines
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In article <8707150100.AA13525@ucbvax.Berkeley.EDU>, SADOIAN@UOFT02.BITNET
 writes:
> Has anyone else noticed that GEMBOOT screws up GFA BASIC's edit screen?

I noticed this effect too, but located GFA-BASIC as the "bad guy",
not GEMBOOT.
GFA-BASIC manipulates the video screen base, and the bug is produced
by a difference between the software screen base (system variable
_v_bas_ad) and the "physical" (controller internal) screen base.
The controller internal screen base is restricted to 256 byte page
bounderies. Unfortunately GFA-BASIC calculates an unbounded address,
probably influenced by GEMBOOT allocating it's cache blocks at the
memory top. The VDI and AES drawing routines are using the software
base and therefore all output is shifted. As the screen memory is
scan line organized this leads to a rotation of the screen image.

  Konrad A. Hahn
  BITNET: XBR4D76H@DDATHD21

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From: XBR4D76H@DDATHD21.BITNET
Newsgroups: comp.sys.atari.st
Subject: Re: GEMBOOT and GFA-BASIC
Message-ID: <8707230803.AA19272@ucbvax.Berkeley.EDU>
Date: Thu, 23-Jul-87 04:03:36 EDT
Article-I.D.: ucbvax.8707230803.AA19272
Posted: Thu Jul 23 04:03:36 1987
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