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Re: IIgs Double HIRES

Subject: Re: IIgs Double HIRES
From: "Michael J. Mahon" <mjmahon@aol.com>
Date: Mon, 13 Feb 2012 01:01:38 -0800
In-reply-to: <jh9mc9$k5m$1@dont-email.me>
Newsgroups: comp.sys.apple2
References: <jh9cpo$slj$1@dont-email.me> <jh9drg$4fo$1@dont-email.me> <alpine.DEB.2.00.1202130102500.3636@zztop.nucleusys.com> <549aa2c2-c54d-46d5-8bd4-051b28e638ac@i18g2000yqf.googlegroups.com> <jh9mc9$k5m$1@dont-email.me>
Reply-to: mjmahon@aol.com
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Daniel Kruszyna wrote:

Marc S. Ressl <mressl@gmail.com> wrote:

Btw, I have a question that has been bothering me for quite some
time... what is the pixel clock for IIGS Super HIRES?



According to the archives, Michael Mahon measured an 8/7 * 14.31818 MHz
dotclock.  I haven't duplicated this exact measurement, but have some
supporting evidence:

The main reason is that the MegaII still controls the video address scanner,
even in super hires modes. The scanner is always clocked by 14M.  It's just
that in super hires, all 8 bits of the video data are used instead of 7.


As noted, the SHR dot clock is 16.36363MHz.

-michael

NadaNet 3.1 for Apple II parallel computing!
Home page:  http://home.comcast.net/~mjmahon/

"The wastebasket is our most important design
tool--and it's seriously underused."

References:
- IIgs Double HIRES
  - From: Daniel Kruszyna <dan@krue.net>
- Re: IIgs Double HIRES
  - From: Charlie <charlieDOTd@verEYEzon.net>
- Re: IIgs Double HIRES
  - From: Vladimir Ivanov <vladitx@XXXyahooXXX.com>
- Re: IIgs Double HIRES
  - From: "Marc S. Ressl" <mressl@gmail.com>
- Re: IIgs Double HIRES
  - From: Daniel Kruszyna <dan@krue.net>

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