Prop2 VGA for Roy Eltham and others ( done to remove seperate issue from chips
![Baggers](https://forums.parallax.com/uploads/userpics/316/nM38GQVOEYVFZ.gif)
Roy Eltham,
RE: your 32bit buffer, as you only have 256KB of RAM, also, with doing 3D you'd have to double buffer the display, so you'd have to do something like 160x120 resolution, admittedly it'd be good for doing less resolution for rendering but would look blocky, and therefore would possibly look worse than banding would, but again due to RAM limitations, you'd only be able to do about 256x192 double buffered in 16bit. [noparse]:)[/noparse] so the choice would be yours. also, it wouldn't matter what the VGA capabilities were, I recon it'd be fast enough to manually code it in asm in one cog to display the VGA image, you'd have about 6 instructions per 640 pixel, so 12 instructions for 320 resolution, which should be more than plenty to read a long and output it to the pins.
Baggers.
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RE: your 32bit buffer, as you only have 256KB of RAM, also, with doing 3D you'd have to double buffer the display, so you'd have to do something like 160x120 resolution, admittedly it'd be good for doing less resolution for rendering but would look blocky, and therefore would possibly look worse than banding would, but again due to RAM limitations, you'd only be able to do about 256x192 double buffered in 16bit. [noparse]:)[/noparse] so the choice would be yours. also, it wouldn't matter what the VGA capabilities were, I recon it'd be fast enough to manually code it in asm in one cog to display the VGA image, you'd have about 6 instructions per 640 pixel, so 12 instructions for 320 resolution, which should be more than plenty to read a long and output it to the pins.
Baggers.
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Comments
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Memory problem for VGA is not so big if Chip Cunstruct SERIN/OUT I proposed with very big speed.
With that SERIN/OUT it is relatively simple construct External MEM controler.
Ps. Even RUN code in COG directly from It.
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Nothing is impossible, there are only different degrees of difficulty.
Sapieha
Post Edited (Sapieha) : 9/8/2008 4:13:21 PM GMT
Which is why PropII should either have external sram controller, so people can put extra memory on it, and all cogs have access to it through a round robin like Hub-RAM, ( which I'd quite prefer even if it meant being half the hub-ram speed ), otherwise you're better off with internal Hub-RAM, well, for my usage of the PropII anyway, others may be happy with single Cog access to external ram through a single Cog.
It's probably why the HX512SRAM from Andre' didn't do as well as it should have with it being 512KB which is a LOT more than the 32KB we now have on Prop1, because you can only access it through one Cog.
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YES and NO.
My proposo to SERIN/OUT is so fast and Chips proposo to VIDEO extensions that You can have one COG to VIDEO and RAM controler att same time.
Proposed Instructions that Auto increment (Maybe even DECREMENT) READ and WRITE to HUB is perfect for that type of work.
It is only programers programing skill that limits possibility.
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Ps. With 32 Bits mode on SERIN/OUT < You can construct RAM controler with relatively simple FPGA·that have upp to 32 Bits Address and 32 Bits wide data bus. Else 4-8 High Bits That have comand to RAM controler and 28-24 Bits Address.
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Nothing is impossible, there are only different degrees of difficulty.
Sapieha
Post Edited (Sapieha) : 9/8/2008 5:12:38 PM GMT
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With the proposed 14bit format you'd only have 5:5:4 or 4:5:5 which would only be 16 or 32 shades of the pure colors and somewhere between 16 and 32 shades of gray (it's not really the full 32). If you move to the full 16bit setup that 5:6:5 in the ideal case, that still only 64 shades of green and 32 shades of red or blue, and again somewhere between 32 and 64 shades of gray.
If you move to 32bit even with the 8bit per component setup you get 256 shades of pure colors and grays. This allows much more accurate color matching on images even if limited to 256 colors at a time (heck even if limited to 128 or 64 colors at a time).
I'm after the color accuracy more than anything.
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For the Propeller/Hydra, I am doing a vertical scrolling shooter kinda like Xevious (old school arcade game) as well as a debugger for ICC.
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Share the knowledge: propeller.wikispaces.com
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