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| Screen mode info http://www.retrosoftware.co.uk/forum/viewtopic.php?f=72&t=584 |
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| Author: | FrancisL [ Wed Feb 02, 2011 3:39 pm ] |
| Post subject: | Screen mode info |
Hi there, I'm looking for information on the various screen modes that the C64 can display. Specifically I'm looking for info like mode name/number (like 'MODE 0' for instance on the BBC), resolution, number of colours, what the available palette of colours is and how the screen would be stored on disc/tape. Is there anything else I would need to be aware of? I've never really worked with the C64 so forgive me if I am asking some really basic questions. Kind regards, Francis |
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| Author: | TomW [ Wed Feb 02, 2011 4:11 pm ] |
| Post subject: | Re: Screen mode info |
C64 doesn't have mode numbers (there's no BASIC or OS support for graphics). There are basically 5 real modes though : Character mode - 40x25 character display. 256 8x8 2 colour characters, one colour is unique, one is background colour. Multi-colour character mode - 40x25 character display. 256 4x8 4 colour characters, one colour is unique, three are background colours. ECM character mode - 40x25 character display. 64 8x8 2 colour characters, one colour is unique, choice of 4 background colours. Bitmap - 320x200 bitmap. 2 unique colours per 8x8 block. Multi-colour bitmap - 160x200 bitmap. 3 unique colours per 4x8 block, 1 background colour. I'm assuming you're mainly interested in bitmap mode. In that you have 8k of bitmap, bytes are in the same order as the Beeb but bits in multi-colour aren't - rather than 12341234 it's more like 11223344. Then you have a 1k 'video matrix', this doesn't have to follow the bitmap but usually does. Each byte is a pair of nybbles, giving 2 of the unique colours - 0 and 1 in standard bitmap mode, 1 and 2 in multi-colour bitmap mode. Then multi-colour mode has an extra 1024 nybbles containing colour 3, but these have to go at a fixed address of $D800. Then colour 0 comes from a VIC register. All modes have the same 16-colour palette, it's at http://en.wikipedia.org/wiki/File:VIC-II_color_map.svg. There are a few software 'extended' modes, eg FLI - 136x200 bitmap. 3 unique colours per 4x1 block, 1 background colour. SuperHires - 96x167 bitmap. 2 'global' colours, 2 unique colours per 8x8 block. There are loads more software modes, but they tend to be more limited in what colours you can have where. Most are described at http://www.studiostyle.sk/dmagic/gallery/gfxmodes.htm if you're interested... |
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| Author: | TomW [ Wed Feb 09, 2011 11:57 am ] |
| Post subject: | Re: Screen mode info |
So has that completely put you off the C64 then? |
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| Author: | FrancisL [ Wed Feb 09, 2011 5:29 pm ] |
| Post subject: | Re: Screen mode info |
TomW wrote: So has that completely put you off the C64 then? lol!  No not quite, but I'll just need a bit of time to digest that. I was just looking for preliminary information with a view to possibly adding it to Image2BBC. Thanks for the info. Kind regards, Francis |
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