Re: 6545 40/80 col register values

From: Rob Clarke <>
Date: Wed, 25 Apr 2012 09:50:16 +0200
Message-ID: <>
Hi André,

It's still not clear to me why different register settings were required 
for 60/50mhz versions when the PET board and monitor operates on DC. Is 
it just to avoid minor artifacts due to ripple on the supply? Also, are 
the register sets independant of the monitor size? I would assume that 
all 80 column machines had 12" displays, but are the registers actually 
setting the machine up for 80 columns or setting it up for a 12" display?


> I had investigated the PET CRTC functionality extensively when I wrote the PET emulator for VICE. It is documented in
> (BTW: the CRTC emulation in VICE is cycle-exact in case you want to test it :-))
> André

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Received on 2012-04-25 08:00:22

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