Rob, Even though it operated on DC wouldn't there be circuitry inside to generate 50 or 60Hz? Commodore bought the monitors from a third party so perhaps the 50/60 depends on which supplier and which location they sourced them from. I'm wondering if it also connected to PAL/NTSC standards? They may have been trying to make the signals compatible so that the video could be sent to an external monitor or whatever. I used to have a board that connected to the user port and converted the video to composite to be used in tv broadcasting. I also have an 8296D computer from europe and I found that the 50Hz rom caused the display to be shifted off the left side of screen when used here in Canada. I had to adjust one of the registers to center it again. I don't know if it made a difference that I was using a 220 to 110 voltage converter that probably worked at 60Hz... I don't think the screen size matters. Steve >________________________________ > From: Rob Clarke <crock@clarke-family.org.uk> >To: cbm-hackers@musoftware.de >Sent: Wednesday, April 25, 2012 3:50:16 AM >Subject: Re: 6545 40/80 col register values > >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? > >Rob > >> >> I had investigated the PET CRTC functionality extensively when I wrote the PET emulator for VICE. It is documented in http://www.6502.org/users/andre/petindex/crtc.html >> (BTW: the CRTC emulation in VICE is cycle-exact in case you want to test it :-)) >> >> André >> > > > Message was sent through the cbm-hackers mailing list > > > Message was sent through the cbm-hackers mailing listReceived on 2012-04-25 15:00:05
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