Re: 1541, PET, 8296 system disk

From: Andre Fachat (
Date: 1998-05-28 10:06:19

Marko Mäkelä wrote:
> Increasing the line length (reg. 0) increases the interval between sync
> pulses and decreases the sync rate.  When the image loses sync and drops
> out, it would resync at twice the new rate, which is close to the usual
> rate.  These values would still not be workable for a 12" display, but
> they might be OK on a 9" display.  This might be the 50Hz equivalent of
> the 970150-07 screen ROM for the 60Hz 9" machine.  This would most likely
> be an EPROM.

Hm. Did you try to figure out the screen refresh rate from the CRTC
values? Some basic formulas and examples are in the PET index, under
CRTC operation. BTW, 63 for register 0 _is_ a value written there
for a 50Hz PET, 80 cols PET.


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Andre Fachat, Institute of physics, Technische Universität Chemnitz, FRG

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