Groups > comp.sys.apple2.programmer > #179

Re: Converting HGR to DHGR

From	Daniel Kruszyna <dan@krue.net>
Newsgroups	comp.sys.apple2.programmer
Subject	Re: Converting HGR to DHGR
Date	2012-02-18 20:58 +0000
Organization	A noiseless patient Spider
Message-ID	<jhp3dl$ige$1@dont-email.me> (permalink)
References	(3 earlier) <alpine.DEB.2.00.1201181105020.20679@zztop.nucleusys.com> <892a42af-44e2-4170-8f2a-8cd606e8c809@u2g2000vbe.googlegroups.com> <6055580d-a21b-49d3-b82b-57414beeff21@b20g2000yqb.googlegroups.com> <alpine.DEB.2.00.1201191310360.11945@zztop.nucleusys.com> <m3wr8lwfd7.fsf@yahoo.ca>

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Jerry <awanderin@yahoo.ca> wrote:
> 80-column mode, and DHGR actually starts seven bits (14.318180 MHz periods)
> sooner (one 80-column character width) than 40-column mode, which explains
> the shift in colors if either you don't do the shift to compensate, or you
> don't simulate the whole dot stream coming out of the shift registers.

I wanted to see how the IIgs does this, and of course it's different.  I used a
different program, but it still switches between 40 and 80 column modes. Text
page 1 in main ram contains 'X' characters, while text page 1 in aux ram
contains 'O' characters. Here are the results:

http://krue.net/junque/iigs_40_80_split_full.jpg
http://krue.net/junque/iigs_40_80_split_close.jpg

Also, I didn't take a picture, but each OX pair in 80 column mode is aligned
with the X of 40 column mode.

-- Daniel

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Thread

Converting HGR to DHGR BLuRry <brendan.robert@gmail.com> - 2012-01-17 07:32 -0800
  Re: Converting HGR to DHGR Vladimir Ivanov <vladitx@XXXyahooXXX.com> - 2012-01-17 18:20 +0200
    Re: Converting HGR to DHGR Antoine Vignau <antoine.vignau@laposte.net> - 2012-01-17 09:10 -0800
    Re: Converting HGR to DHGR BLuRry <brendan.robert@gmail.com> - 2012-01-17 09:26 -0800
      Re: Converting HGR to DHGR Vladimir Ivanov <vladitx@XXXyahooXXX.com> - 2012-01-18 11:17 +0200
        Re: Converting HGR to DHGR BLuRry <brendan.robert@gmail.com> - 2012-01-18 11:04 -0800
          Re: Converting HGR to DHGR BLuRry <brendan.robert@gmail.com> - 2012-01-18 20:34 -0800
            Re: Converting HGR to DHGR Vladimir Ivanov <vladitx@XXXyahooXXX.com> - 2012-01-19 13:12 +0200
              Re: Converting HGR to DHGR Jerry <awanderin@yahoo.ca> - 2012-01-21 02:53 -0700
                Re: Converting HGR to DHGR Vladimir Ivanov <vladitx@XXXyahooXXX.com> - 2012-01-21 18:48 +0200
                Re: Converting HGR to DHGR Daniel Kruszyna <dan@krue.net> - 2012-02-18 20:58 +0000
                Re: Converting HGR to DHGR BLuRry <brendan.robert@gmail.com> - 2012-02-18 15:00 -0800
  Re: Converting HGR to DHGR "ict@ccess" <gids.rs@sasktel.net> - 2012-02-19 19:05 -0800

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