Re: Apple IIgs video modes?

[ltchean@iss.nus.sg (Lim Thye Chean)]

carl@busop.cit.wayne.edu writes:
: 
: I am new to Apple IIgs computers and I was wondering if someone could list 
: its video mode specs, like resolution and color.  From what I remember I 
: heard it could do a maximum of 256 colors on screen, but only 16 different 
: ones per scanline out of a palette of 4,096.  But then I've seen these 
: pictures that claim to be 3,200 colors.  So what's the scope?

OK, a simple summary. There are 2 video modes: 320 x 200 and 640 x 200. 
There are 4096 colours to choose from. On 320 x 200 mode, a palette can
contain 16 colours. On 640 x 200 mode, a palette can contain 4 colours or
15 dithered colours. Each line has a palette.

On either mode, you can have up to 16 palettes per screen. That is, if you use
16 palettes on 320 x 200 mode, and since each palette contains 16 colours, you
get up to 16 x 16 = 256 colours. Under 640 x 200 mode, that is 4 x 16 = 48
colours.

If there is a program on the background swapping palettes, you can have up
to 200 palettes displayed at one time. That is, each line has its own palettes.
So you can have 16 x 200 = 3200 colours. But I have never seen a 3200 picture
uses more than 256 colours.

: Thanks

You are welcome.

: -
: Carl Mueller
: Wayne State University
: email: carl@busop.cit.wayne.edu

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