If using composite video and a PAL TV, you can also blend colors by using alternating horizontal stripes because PAL TVs use a delay line to cancel the chroma information with the line above it. Exactly what color you got would depend on the specifics of your TV's decoding.
Secret colours of the Commodore 64
31–40 of 100 posts
Re: Secret colours of the Commodore 64
#32I once toyed with Temporal dithering on VGA ModeX. While the bullet point listed resolution for standard VGA was 320x200. Hitting the hardware registers and paying the price of a rather peculiar addressing mechanism for pixels you could get a lot more(and double buffering to boot). 320x240 was the most common tweaked mode, because it gave you square pixels and page flipping. At the edge of what momitors could handle…
I'm pretty sure I've seen this used in the demo scene, but I can't name any productions after all these years. I remember Second Reality has a mode x plasma at least
i think one of the assembly party reports (94?) used it to show true color photos on vga.
Re: Secret colours of the Commodore 64
#33Off topic-ish: There was a trick you could use on the Atari ST to display more than the allowed number of colours - you reloaded the palette data on each horizontal interrupt. Could this have been used on the C64 also?
Re: Secret colours of the Commodore 64
#34Here's a great older example of this technique (and a couple others) used on the TRS-80 Color Computer 3 to show "hi-color" bitmaps on a machine with a 16 color palette: http://users.axess.com/twilight/sock/hicolor/hicolor.html
Wow. Thanks! This CoCo is still teaching me. Love that thing.
Re: Secret colours of the Commodore 64
#35Near the bottom, I wonder if high-speed img flipping in js could be done by absolute-positioning the two images and toggling display:none/display:block (or flip the z-index above/below) on the upper layer on every animation frame?
I think you'd have better luck with rendering a pair of ImageBitmap to a canvas via requestAnimationFrame.
Would either be faster on mobile? I feel like a gif would have been better in this case, and I generally dislike the format.
Re: Secret colours of the Commodore 64
#36Off topic-ish: There was a trick you could use on the Atari ST to display more than the allowed number of colours - you reloaded the palette data on each horizontal interrupt. Could this have been used on the C64 also?
There was no palette to reload - the C64 (like most 8-bit systems) had a fixed palette in hardware.
Re: Secret colours of the Commodore 64
#37> Sidebar: A note on frames per second. The European PAL C64 updated at 50fps, whereas the US NTSC systems updated at 60fps
This is because alternating current is 50Hz in PAL countries (eg Europe), and 60Hz in NTSC countries (eg America). Analogue TVs vertical refresh rate was synced to the AC frequency for a bunch of practical reasons, which meant gaming consoles had to send signals to the television at either 50Hz or 60Hz.
Result? Many PAL console games actually ran at 5/6ths of NTSC speed. Most notoriously, Sonic the Hedgehog, whose agility was more sluggish (and soundtrack less vivacious) for a large fraction of the world. More information in this video: https://www.youtube.com/watch?v=cWSIhf8q9Ao
Re: Secret colours of the Commodore 64
#38Off topic-ish: There was a trick you could use on the Atari ST to display more than the allowed number of colours - you reloaded the palette data on each horizontal interrupt. Could this have been used on the C64 also?
There was no palette to reload - the C64 (like most 8-bit systems) had a fixed palette in hardware.
But you could interrupt the CPU from the graphics chip based on scan line (just in case that's the part GP was interested in), for instance to do a classical graphics/text screen split or replicate sprites.
Re: Secret colours of the Commodore 64
#39I would think answer is NO, but (why not) is there a way to synchronize painting of the picture with the vertical synchronization of the screen in modern browsers, to prevent flickering?
Re: Secret colours of the Commodore 64
#40Cool article, but the Spectrum really only had 7 colours and black. And at the time I hated the Commodore 64's colour palate (and any non ZX Spectrum palate, until I saw the beautiful SAM Coupé's) so I guess it's a matter of preference.
I also preferred the vibrant colors of my CPC to those of a C64.