On 11/07/2017 04:02 PM, smf wrote: > 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 AGNUS is a HMOS-II chip, so you can pull the sync signals low without problems. But you must never pull them high with any kind of power enough to override the signal since that might overload the output driver in AGNUS. Gerrit Message was sent through the cbm-hackers mailing listReceived on 2017-11-07 16:01:34
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