Re: [oc] Media Chip for 8bit/CRTC

[Niclas Hedhman <niclas@internuscorp.com>]

The one and only question; WHY?

What's wrong with today's graphics accelerators?

Niclas

On Thursday 06 March 2003 07:39, Damien Légiéda wrote:
> Hi,
>
> If you look at the old 8 bit computers (MSX, Commodore etc) and at new 8
> bit computers (CommodoreOne, Sprinter...), they use classic CRTC6845.
>
> My aim is to build, via an FPGA, a chip that gives to computer using this
> CRTC6845 somes new exciting and originals features. This FPGA will include
> too an expansed version of the old AY sound chip.
>
> I search actually people interrested to help me in the development of this
> FPGA. If you're interrested and if you have knowledge about FPGA and VHDL,
> please contact me as soon as possible.
>
> The features of my FPGA :
>
> A) Soft scroll facility : A memory mapped soft scroll control register
> (SSCR) allows scrolling of the screen by pixels rather than just by
> characters as at present with stand alone CRTC. It is cleared at reset.
> This soft scrolling mechanism affects the whole of the main screen,
> regardless of the split screen facility, but it does not affect sprites.
>
> B) Split Screen facility : Three memory mapped registers  provide a
> horizontally split screen facility. One defines the scan line after which
> the screen split occurs. A value of zero (as at power on reset) will turn
> this feature off.
> Must i think about the possibility of vertical split screen too ?
>
> C) Hardware Rupture Pointer
> A pointer shows bytes corresponding to the next pixel to be displayed. We
> can change this pointer in real time, increment of disincrement it or
> change the adress. With this trick it’s possible to do hardware zoom and
> have differerents videos modes. For those who don’t know what is a
> “rupture” : imagine you have 2 pictures in your video RAM. You decide to
> display only the first 100 lines of the picture 1 and after the first 100
> lines of the picture 2. After you can scroll up and down one image line per
> line.
>
> E) resolution and colors selection
>
> F) Classic AY with 3 voices, sound generator etc.
>
> G) Advanced part of the AY : 8 ADCPM voice for 3D space perception.
>
> H) An unit able to draw simples textures by using a fractal algorithm.
> My idea is to have in hardware a generator of textures using fractals
> curves. This kind of process take a lot of CPU time but perhaps if
> everything is implemented directly in hardware, it's possible to do it.
> What is interresting with this trick is the possibily to reduce or increase
> the size of the texture without a loss of quality. In the same time, you
> don't need a compression/uncompression algorithm.
>
> The aim with fractals textures is to economise the RAM when we build a not
> very complex texture. Indeed in a racing game for example, one does not
> need to make 3 hours of Photoshop to make a texture of the track. All these
> textures simple and not really interesting can be generated automatically.
> Moreover, if the video coprocessor is well made, apply this kind of texture
> will be faster than apply "a true" texture (not RAM access in reading): One
> holds the power for the
> interesting things.
>
> If the graphic designer wants to play with fractals textures, it is
> necessary that it can parameterize them to obtain some interestings
> results. Only the parameters of textures would be stored. That would give
> for example "the texture which I want has a granularity of 50, the random
> numbers are generated using the starting value 89, the palette used is a
> range of green towards the black, RGB color #0 is transparent, the points
> at the ends of my triangle are 50,89 and 665.". With these parameters the
> video processor generates complete texture. The aim is to offer the maximum
> of parameters with which the graphic designer can play.
>
> I think with this kind of system it's possible to draw simple texture like
> wood, skin, fur etc.
>
> Is there here interrested people ?
>
> Dam'
>
>
>
>
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