Re: Interlacing the 64 (was: C65 on Ebay)

From: silverdr_at_wfmh.org.pl
Date: Mon, 6 Nov 2017 19:19:29 +0100
Message-Id: <B4B79B18-7F57-446C-BD48-67A582145963@wfmh.org.pl>
> On 2017-11-06, at 16:58, Mia Magnusson <mia@plea.se> wrote:
> 
>> It is essentially what I described a while back for making c64 output
>> a valid pal/ntsc signal while maintaining perfect sync between the
>> cpu/sid & vic, by speeding up/slowing down the system clock to make
>> the sync pulses hit at the correct time.
>> 
>> I wasn't considering syncing to an external sync, which would add
>> some complexity. But it would be an awesome project.
> 
> If you want a signal that has correct interlace you cannot do this
> without breaking sampled audio playback, as you have to halt the VIC
> chip for one line to insert the interlace line.

AFAIR The idea was to slow down/speed-up the clock so that no halting would be necessary.

> The only way to avoid
> this is to have a buffer for video signal that can hold up to one line,

which was my idea from the very beginning..

> and run the VIC so the v-sync is perfectly aligned but H-sync slightly
> off so it will drift exactly one line until that extra blank line is
> needed...

... and generate the proper pulse sequence for odd/even field.

-- 
SD! - http://e4aws.silverdr.com/


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Received on 2017-11-06 19:02:32

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