Quote from: alex_79 on 17 Jan 2025, 06:59 PMSo, maybe that could be the reference for the "intended" palette?

Yes! That would be brilliant.

Do we know anyone with a single chip 2600?

BTW, the single chip "JAN" Atari Junior has no way to adjust the color phase. There's no pot on the board.

The schematic of the "Atari 2100" (prototype of the Jr.) shows a 48 pin Chip and there's no "Color Adjust" or similar pin like in the TIA (edit: the chip pinout is in the Jan programming guide too). The actual single chip Junior that was produced has a 64 pin chip, and no schematic or official doc exist for it. But the additional pins compared to the prototype pinout are either connected to GND or left floating, so the phase is determined by the chip itself here too.

So, maybe that could be the reference for the "intended" palette?

Quote from: Thomas Jentzsch on 17 Jan 2025, 07:23 AMWhat a mess! Also color 14 is now "gold".

Oh yes! I didn't notice that.

I'm not sure what to make of it. I'll have to meditate on this new information.

What a mess! Also color 14 is now "gold".

Did they change this for a reason? Or was there just total chaos?

Quote from: Thomas Jentzsch on 17 Jan 2025, 04:48 AM

QuoteCodes 2 through 15 shift the phase from zero through almost 360 degrees allowing selection of 15 colors.

Almost 360 degrees? We are running in circles.

Heh

The attached table on Page 38 of the JAN programming guide, seems to support the VideoSoft test cartridge calibration instructions. "Light Orange" for Hue 1 and Hue 15

QuoteCodes 2 through 15 shift the phase from zero through almost 360 degrees allowing selection of 15 colors.

Almost 360 degrees? We are running in circles.

Quote from: JetSetIlly on 16 Jan 2025, 11:15 PMI suppose I'm wondering why the Programmer's Guide is telling us that the colour burst happens on 16 counts. Unless I've missed something, that's not information that's useful to the programmer.

Knowing the length of the color burst is of no interest for a programmer, but that part is from the document called "TIA 1A", which is a hardware manual and contains some more technical oriented info such as timing diagrams. This was a separate document from the actual TIA Programmer's Manual, but they are both included in the reconstructed PDF and HTML versions that's been floating around for many years.
The "Programmer's Guide" used in that case was the '79 version, but there are scans of others versions floating around.

In the "Jan" manual (the combo chip that includes 6507, RIOT and TIA in the same package, used in some "Junior" models), there's this paragraph about color phases:

QuoteThe color phase shifter produces a reference color output (color burst) during horizontal blank. Then during the unblanked portion of the line it produces a color output shifted in phase with respect to the color burst.
The amount of phase shift determines the color and is selected by the four color code lines from the color-lum multiplexer. Code 0 selects no color. Code 1 selects light orange (same phase as color burst). Codes 2 through 15 shift the phase from zero through almost 360 degrees allowing selection of 15 colors. Each phase shift is approximately 20 ns from the reference color output. Two phase shifts would have a delay of approximately 40 ns.

The TIA manual from COLECO (in which the TIA is actually referred to as "VIC", for Video Interface Circuit) defines color "$1x" as "YELLOW-ORANGE" (page 65)

16 counts = 16 hues?

Quote from: JetSetIlly on 16 Jan 2025, 09:33 PMBut there are other possibilities perhaps. How does the console produce the colour burst? According to the Stella Programmer's Guide page 18.

   // "A hardware counter on this chip produces all horizontal timing (such as
   // sync, blank, burst) independent of the microprocessor, This counter is
   // driven from an external 3.58 Mhz oscillator and has a total count of 228.
   // Blank is decoded as 68 counts and sync and color burst as 16 counts."

Does that tell us anything useful? I'm not sure.

I suppose I'm wondering why the Programmer's Guide is telling us that the colour burst happens on 16 counts. Unless I've missed something, that's not information that's useful to the programmer.

Quote from: Thomas Jentzsch on 16 Jan 2025, 07:17 PMNot sure if that will help. Probably you need more than one to even get an idea. Plus multiple CRT TVs.

The immediate problem I want to solve is the natural colour of hue 1. Based on the information we have, I don't believe hue 1 would ever change between consoles (the adjustment pot doesn't change the output of hue 1 -- according to everyone who has answered so far).

The purely mathematics answer is that hue 1 is that weird greeny-yellow. But as you say, that doesn't match the descriptions in the old manuals. The only thing I can think of is that when Atari said "gold" what they mean is, "tune your TV so that hue 1 is gold", rather than, "the natural output of hue 1 is gold".

But there are other possibilities perhaps. How does the console produce the colour burst? According to the Stella Programmer's Guide page 18.

   // "A hardware counter on this chip produces all horizontal timing (such as
   // sync, blank, burst) independent of the microprocessor, This counter is
   // driven from an external 3.58 Mhz oscillator and has a total count of 228.
   // Blank is decoded as 68 counts and sync and color burst as 16 counts."

Does that tell us anything useful? I'm not sure.


The issue of what phase the hues are I've more or less settled on. I think it's the "Field Service Manual". I don't think we'll get a better answer than that, despite it being a very vague description. 24degrees is right out. Despite how perfect an answer it might be, it's just wrong.