Marko Mäkelä wrote: > If I remember correctly, my demo program would switch the display to an > interlaced 8x16 font on the 6560. Hm, I always thought the interlace bit on the 6560 just toggles the chip from producing 30 full (progressive) frames @ 60 Hz to producing 60 half (interlaced) frames. Does the perceived vertical resolution really improve? On newer computers like the Amiga, interlaced mode really means double vertical resolution at the cost of flicker unless you have a monitor or flicker fixer than can handle it. I have read about NES and probably also C64 units that produce a progressive video signal which some newer TFT, LCD, Plasma etc TV's spew upon since they expect an interlaced signal. Also I seem to remember the interlace bit on the 6560 was introduced only for Zenith TV's, which suggests to me they would have a problem with a progressive video signal. I doubt we ever had Zenith in the PAL world, so this bit would then not make any sense. More interesting are the value ranges used on the 6560 and 6561 chips. Screen positioning in horizontal and vertical directions cover completely different value ranges, which is why all VIC-20 cartridges made for NTSC systems display the picture in the upper left corner on a PAL machine. Many of them let you center the display though. I understand the 6560 was completed before the 6561, so possibly due to the PAL display is larger they came up with different ranges for positioning. Also the granularity of screen positioning is different; the 6560 has far fewer steps than the 6561 has. I own both types of VIC's, but as I only have PAL TV's of which some will accept NTSC composite video in colour, I can't say for sure how a real NTSC TV or monitor would act. At least I got no action at all by toggling the interlace bit on my NTSC VIC-20 using a PAL monitor. Best regards -- Anders Carlsson Message was sent through the cbm-hackers mailing listReceived on 2011-08-26 10:00:19
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