Re: Innovative Amiga genlocking

From: smf <smf_at_null.net>
Date: Tue, 7 Nov 2017 15:02:31 +0000
Message-ID: <b9d4fa6d-9def-3ea6-086d-a5e1c40a9cc2@null.net>
On 06/11/2017 18:23, Gerrit Heitsch wrote:
>
> Why not? I'm looking a the schematics for the A500+. There the Circuit 
> to switch between the internal crystal and external clock is a 74F258. 
> That means that the 8375 AGNUS doesn't know what clock it's running on 
> and should happily produce sync even with external clock. Same for the 
> A1000.
>
Looking back at some notes the hsync/vsync pins are unbuffered and you 
can override them by dragging them high/low. It looks like ERSY bit in 
BPLCON0 turns off the internal generation, going by the write up of how 
kickstart detects a genlock http://eab.abime.net/showthread.php?t=80192

I suspect they have the ability to disable the internal generation 
because having both sides fight could cause double pulses if they were 
switching close to each other.

The video mixing functionality is seperate from the genlocking. ECS was 
more configurable, IIRC OCS was just colour 0 detection.



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Received on 2017-11-07 16:00:03

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