MEGA65 FORUM

4096 Colors

append delete paulaftw

I looked at the video modes documentation at https://github.com/MEGA65/mega65-core/blob/px100mhz/doc/viciv-modes.md and I wonder whether it would be feasible to support 4096 color HAM6 (6 bits / pixel) mode in VIC-IV? Would it be possible regarding performance and diespace? Would it be a good fit to the "feel" of mega65? Could the code be borrowed from an fpga amiga implementation?

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append delete #1. Daniël Mantione

Well, personally I'm not sure if 4096 colour HAM6 is superior to a mode with 256 out of 16 million colours. The number of unique colours possible on the screen is obviously higher, but only 6 bit fidelity is a major drawback and the loss in horizontal detail comes in addition to that.

On the Amiga it was a different story, because the Amiga could display only 64 colours in bitplane mode, so HAM6 was a welcome addition to display photo-realistic pictures. For the Mega65 on the other hand, which can do 256 colours in textmode and bitplane mode, I am not so sure if it adds anything usefull.

append delete #2. gardners

So, with a DMA speed of 25MB/sec, you can change a palette byte about every two pixels. The big challenge is that with only 128KB RAM, you will run into bigger problems quite quickly ;) However, it would be quite easy to change the palette every character row, and have 256 unique colours per 8 rows of pixels. You could also do a bit of sprite trickery to use the sprite palette bank to get you 512 colours in that space. So not exactly HAM, not exactly FLI, but something new and interesting to explore.

append delete #3. paulaftw

How about HAM8? It uses 8 bits per pixel. http://www.amigans.net/modules/AMS/article.php?storyid=22 It would enable maximum of 16M colors without raster tricks.

append delete #4. PGSmobile

Yes, something like ham8 would be possible to implement, and wouldn't be too hard to do. Due to the mega65s ability to pick from 4 palettes of 256 colours, you could make a mode that was slightly more flexible than ham8.

append delete #5. Travis b moore

So are you doing direct video 800 by 600 or digital multiplex 32 bit graphics. Or multiplex video color for true 8 bit color or something. It may be 256 color but I had thought hacking the video out chip might up it or a software trick could do something neat?

append delete #6. gardners

We are doing direct 800x600. There are 4 palettes with 256 24-bit colours each, i.e., palette entries for 1024 unique colours. By switching palettes in real-time, you could do crazy things ith this.

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