Re: Converting a Commodore 64 from NTSC to PAL

From: silverdr_at_wfmh.org.pl
Date: Fri, 13 Apr 2012 14:56:00 +0200
Message-Id: <47E99E67-48D7-46B1-AF30-D48755B0BDB9@wfmh.org.pl>
On 2012-04-13, at 14:48, Rob Clarke wrote:
> 
> 
> The TOD clock on the CIA's has a control bit which indicates whether the
> clock signal is 50 or 60 hz. I could not for the life of me remember how
> this gets set by the Kernal.

In the 64 there is a flag at $02A6, which is set on the POST. I don't recall if this value is used elsewhere in the KERNAL but wouldn't be surprised if it isn't.

> The CBM-II's had a jumper on one of the TPI's
> but AFAIK, the only jumper on the 64 boards was only for the clock
> divider, and not hooked up to any of the control ports. As the 64 kernal
> was region agnostic, how did it set the 50/60hz control?

By checking for raster IRQ at NTSC non existent line. 311 AFAIR.

-- 
SD!
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Received on 2012-04-13 13:00:52

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