Retro-Nerd schrieb am 16.03.2026, 07:58:
Gibt mal wieder ein grafisches Update der C64 Fassung. Sieht wirklich schick aus.

LINK

Philip "Pepto" Timmermann, <[email protected]>


P.S.: Here's an interesting eMail which Bob Yannes (co-developer of the VIC-II) sent to me. Please note that I can't disclose Bob's eMail address to you, as he's very concerned about his privacy and the only way to get in touch with him myself, was through a third person, who forwarded our mails to eachother. In other words, I don't have his eMail-address myself, so don't ask. Additionally please note that Bob talks about the NTSC color wheel. NTSC uses YIQ instead of PAL's YUV, but in order to convert from YIQ to YUV you just have to rotate everything by 33° and exchange the color-difference axis. This is what they probably did in hardware in order to make the VIC-II work with PAL and so NTSC and PAL-VIC's probably have the same colors.




Subject: "Re: VIC-II colors"
From: Robert 'Bob' Yannes
To: Philip 'Pepto' Timmermann
Date: 27.09.1999

I was involved with the development of the VIC-II, however the actual implementation of the design, including the Color Palette, was done by someone else. I have forwarded your message to him, but it is up to him if he wants to respond.

I can tell you that the design was based on the principle that adding a sine wave of a particular frequency and amplitude to an inverted version of the same sine wave at a different amplitude produces a phase-shifted sine wave of the same frequency. The amount of phase shift is directly proportional to the amplitudes of the two sine waves.

The VIC-II used the 14.31818 MHz master clock input (4 times the NTSC color burst frequency of 3.579545 MHz) to produce quadrature square-wave clocks. These clock signals were then integrated into triangle waves using analog integrators. The triangle waves were then integrated again into sine waves (actually rounded triangle waves, but good enough for this application). This produced a 3.579545 MHz sine wave, inverse sine wave, cosine wave and inverse cosine wave.

An analog summer was used to create the phase-shifts in the Chroma signal by adding together the appropiate two waveforms at the appropiate amplitudes. The Color Palette data went to a look-up table that specified the amplitude of the waves by selecting different resistors in the gain path of the summer. The end result was that we could create any hue we wanted by looking at the NTSC color wheel to determine the phase-shift and then picking the appropiate resistor values to produce that phase-shift.

Color Saturation was controlled by scaling the gain of the summer. When we picked the resistor values to determine the output phase-shift, we also scaled them to produce the desired output amplitude. Luminance was controlled using a simple voltage divider which switched different pull-down resistors into the open-drain output. We could create any Luminance we wanted by choosing the desired resistor value.

I'm afraid that not nearly as much effort went into the color selection as you think. Since we had total control over hue, saturation and luminance, we picked colors that we liked. In order to save space on the chip, though, many of the colors were simply the opposite side of the color wheel from ones that we picked. This allowed us to reuse the existing resistor values, rather than having a completely unique set for each color.

I believe that Commodore actually got a patent on this technique. It was certainly superior to the Apple or Atari approach at the time, as they ended up with whatever colors that came out — ours allowed the designer to freely select Hue, Saturation and Luminance.

Since all of this was based on selecting different resistor values and resistance varied from chip lot to chip lot, there was variation from one Commodore 64 to another. It wasn't as bad as it could have been though, since all of the Chrominance selection was based on resistor ratios, which could be kept constant even if the actual resistor values varied. Luminance was more of a problem. A trimmer resistor should really have been used to pull up the output. This would have allowed the Luminance to be adjusted for consistency from unit to unit, however Commodore didn't care enough about consistency to bother with adjusting each unit.

—
Robert 'Bob' Yannes

Retro-Nerd schrieb am 13.04.2026, 17:10:
Ja, es ist die falsche Pepto Palette, und die neuere Colodore Palette von ihm sieht deutlich besser aus. Aber selbst das ist nicht das, was ICH von damals auf dem C64 so kannte. Es gibt nicht umsonst diese ganzen verschiedenen Paletten in Emulatoren. PALette von Tobias aus dem Forum64 kommte meiner Erinnerung an alten Röhren TVs/Monitoren am nächsten, das Gelb sieht hier z.B. nochmal etwas anders aus.

Hardy Heßdörfer schrieb am 11.03.2019, 21:07:
Was habe ich das Buch geliebt, witzig war, dass statt Screenshots Zeichnungen der Spielszenen verwendet wurden. Es gab ja auch einen zweiten Band von Rene Zey namens "neue Game Boy Spiele", ebenfalls aus dem Hause Falken, wieder mit Zeichnungen.

v3to schrieb am 13.04.2026, 14:26:
@Christian Keichel

Blass ist nicht gleich blass, wenn die Farben im Ursprung insgesamt kräftiger sind und man nicht die Einstellungen bei Commodore kennt.

Hier wird aus der Erinnerung erzählt und kennt man ja auch von sich selbst, immer auch damit, was man als Referenzvergleich hat. Was von Seiten Commodore nie dokumentiert wurde, ob es einen Farbstandard gab, nach dem die Farben abgeglichen wurde (ich wüsste jedenfalls keine Quelle und so, wie ich die Interviews verstehe, gab es das auch nicht). Bzw ob für PAL-Geräte die Farben neu gesetzt wurden (was ich in Ermangelung an Quellen bezweifeln würde und davon ausgehe, dass die Grundlage auf den selben Farben beruht. Da stellt sich doch eher die Frage, ob hier vielleicht weniger die Lochmaske eine Rolle spielt oder vielleicht doch die 30% höhere Farbfläche je Pixel, weil sich die Bleeding-Effekte bei NTSC vielleicht nicht so stark auswirken).

drym schrieb am 13.04.2026, 12:23:


der langjährigen, langsam ergrauenden User hier

v3to schrieb am 13.04.2026, 13:56:
@Christian Keichel

Ja, richtig. Und entsprechend ist die Argumentation mit der Sättigung bei Festlegung der C64-Farben etwas holprig, wenn die Leser hier in den Kommentaren, die vermutlich nur die PAL-Wiedergabe kennen, die ursprünglichen Farben nie gesehen haben. Die Farben bei NTSC-Systemen kommen, wie gesagt, deutlich satter rüber als auf PAL (was mMn durch die größeren Farbfläche pro Pixel bei NTSC-C64 entsteht - nicht wg dem Videostandard, sondern weil es vertikal etwa 20% weniger Rasterzeilen sind),