VIC 20 in Black and White mode

[Jeff-20]

I was looking at the Color/Black and white switch on the Atari 2600. I was wondering: Is there a way to disable color information output on the VIC 20? I know it seems like a silly question, but I am just curious if any of you have theories on how one might achieve this via hardware or programming.

[Boray]

If it was possible with just programming, then I guess it already would have been done, to make pictures with many grey shades.

[Mike]

There's no provision in the VIC registers, or elsewhere, to switch off chroma output from the VIC chip. With a hardware hack, one might put an analogue switch on to the chroma output pin for this. This could be combined into the S-Video mod.

Anyway, if you intend the video output to be looked at in B/W fashion, you could always notify the user beforehand to turn down the saturation.

[GreyGhost]

yeah, my monitor has a knob.

[English Invader]

Of course, you could always just buy a black and white television .

[adric22]

Of course, you could always just buy a black and white television .

Skip the B&W television and go for the old monochrome green Amdek monitors. Those were awesome. I actually used to use one of those on my Amiga 500 in the early 1990's on the composite out port for several months after my 1084 had an unfortunate accident. Even though I missed having color, I realized that the Amdek was quite a bit sharper than the 1084 and text was much crisper and easier to read.

[Schema]

Of course, you could always just buy a black and white television .

I only had a black and white television for my VIC as a kid, it's still somewhat of a novelty for me to see the games in color. (And I walked to school through 6 feet of snow, uphill both ways. )

[Pedro Lambrini]

Just curious but is this relevant to your new project, at all?

[ravenxau]

poke36879,8

ctrl - 2

[Jeff-20]

Just curious but is this relevant to your new project, at all?

yes.

poke36879,8

ctrl - 2

And for grey shades?

[carlsson]

Use cross patterns, something like this:

Code: Select all

*.*.*.*. *...*... *....... *.......
.*.*.*.* ..*...*. ....*... ........
*.*.*.*. *...*... *....... ....*...
.*.*.*.* ..*...*. ....*... ........
*.*.*.*. *...*... *....... *.......
.*.*.*.* ..*...*. ....*... ........
*.*.*.*. *...*... *....... ....*...
.*.*.*.* ..*...*. ....*... ........

You get the idea. These kinds of patterns have been used in various plasma effects in VIC-20 demos in the past 10-13 years. While they are not true shades of grey, often they look quite good despite the relative low resolution of the VIC.

[Mike]

Use cross patterns, something like this:

I use a similar method with PGM IMPORT. Here, two intermediate colours help to give a more convincing effect.

With these ordered dither patterns, one must be rather careful in their design, so that transitions from one intensity level to the next don't catch the eye because the neighboring patterns don't fit. In my program, the dither patterns are defined in the lines 35 to 38.

Still, there's no provision within the VIC-20 hardware itself to produce *unsaturated* colours, other than black and white - and I thought the matter had been sorted out. In that regard, I found ravenxau's posting to be a rather unsuccessful attempt at a joke.

[Jeff-20]

C'mon, it was funny. Still, it would have been nice to achieve a grayscale. Sigh.

[Mike]

Jeff and I had a quick PM exchange during which I got an working idea to produce unsaturated display colours on the VIC-20, with PGM IMPORT being one component - I love to prove myself wrong.

This will be added to the MINIPAINT batch suite soon. So stay tuned.

Michael

[Pedro Lambrini]

Sounds interesting. A whole new range of colours...can they be used for game purposes or only in a demo situation?