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[oc] Media Chip for 8bit/CRTC
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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