custom co-processor chips like the SVP?

For anything related to cart (SRAM, SF2 mapper, audio, CD mode 1, ...)

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Chilly Willy
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Post by Chilly Willy » Sat Dec 08, 2012 8:18 pm

One thing I would suggest - I always thought the SVP failed because it wasn't a lock-on product. This would be even more of an issue now then back then. Is a homebrewer going to spend EVEN MORE money on a custom cart than what it already costs to make a repro/homebrew cart? The A2600 cart I mentioned is a flash cart, so it can run any homebrew that works on it. A Genesis coprocessor cart would need to either also be a flash cart, or be lock-on.

Nintendo only managed to put add-on chips in carts because of scale of economy - they were making and selling MILLIONS of the carts. A modern homebrew version aimed at a "dead" console like the Genesis might sell a few hundred... MAYBE a few thousand. There's no economy of scale, which is why flash carts are generally fairly pricey compared to a regular game cart. So whatever a coprocessor cart costs has to be split over multiple games, which means a flash cart or a lock-on cart.

Interestingly enough the Mega-Everdrive fits this thread - it's an FPGA flash cart for the Genesis. If it had more documentation for doing your own FPGA designs, it would fit one of the types of carts asked for here. But note the price - almost $150 shows that a cart like this isn't going to be a cheap thing.

tinctu
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Post by tinctu » Sat Dec 08, 2012 8:55 pm

price limit should be 45euro...

best way is to have flash rom+mcu with usb support they both are low priced...
for example flash 8gb...

RayR
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Post by RayR » Sat Dec 08, 2012 8:56 pm

Chilly. I'm on the same page as you. I was mulling the numbers and came up with figures close to yours based on realistic expectations. Coming from the music world I'm used to buying DIY electronics kits and assembling them myself. It's a way of saving money. That may be one way to do it. I could see a small library of games using the cart as a standard. It might take a year or two to build up momentum but it could be a homebrew standard. Ultimately it's more of a passion thing at the start. Even if nothing special came of it I would enjoy coding my own project and learning and expanding my knowledge. That's what I enjoy the most.

djcouchycouch
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Post by djcouchycouch » Sat Dec 08, 2012 11:28 pm

I'd like to mess around with one for Goplanes, if ever I had the chance.

Don't exactly know what I'd do with it, though :)

Chilly Willy
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Post by Chilly Willy » Sun Dec 09, 2012 3:55 am

Hey, look at this - a dual-core ARM, 204 MHz, 168KB of ram, lots of modules, in a 144 LQFP, for $8.50 in single unit quantities.

http://www.digikey.com/product-detail/e ... ND/2840457

Same thing, but 264KB of ram for $9.38:
http://www.digikey.com/product-detail/e ... ND/2840463

tinctu
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Post by tinctu » Sun Dec 09, 2012 9:06 am

Cool find. Dual core is good. One core can act as CPU accelerator second one as GPU for example. Or second as support CPU... And very good prices. I think ARM will be best choose. There is C there is PASCAL there is even BASIC IDEs for ARM. They are low priced. Well documeted CPUs. And they will be produced in future too. Plus writing emulator of that turbocartridge for PC, MAC will be more simple that for other CPUs...
Best will be using that ATARI 2600 harmonycartridge scheme. Superfast ARM for program and SEGA HW for making graphics and sound... And on dualcore ARMs you will be able superfast emulate 68k or Z80 or SH opcodes... Or ever emulate your own instructions. So people who dont like ARM will use their own solutions.


Here is my fav PASCAL for example>
http://www.freepascal.org/

tinctu
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Post by tinctu » Sun Dec 09, 2012 9:18 am

BTW SEGA VDP
Display palette: 512 colors (3:3:3 RGB)
Onscreen colors: 64 (normal) or 183 (shadow/highlight mode)

On Atari ST:
Low resolution: 320 × 200 (16 color), palette of 512 colors

But ATARI sceners have developed little trick for using all 512 colors...
http://www.leonik.net/dml/sec_pcs.py

Here is 4096 STE version...
http://www.youtube.com/watch?v=w5EbCT0W_Ds

Maybe something similar can be done for Megadrive too. And when there will be ARM as CPU, 68000 can do that palette trick...

Chilly Willy
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Post by Chilly Willy » Sun Dec 09, 2012 6:37 pm

The ST may only do 16 colors, but it has a dedicated DMA channel that allows the palette to be set for every single line of the display. Most of the time, games just change it at set places as it's too hard to do a dynamic display in real time, but it is handy. For example, Wolf3D-ST uses one set of 16 colors for the display, and changes to a second set for the status bar. It also uses 16 color for every line for the title screen and option screens.

RayR
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Any hardware engineers up to the challenge on this one

Post by RayR » Tue Dec 11, 2012 6:10 pm

That would be great. Looks like there are other expansions out there in the retro world.

http://www.atarimuseum.com/videogames/c ... expansion/

I wish I hard the hardware skills. I can only support and encourage those who take the plunge.

tinctu
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Post by tinctu » Tue Dec 11, 2012 6:30 pm

I will produce transparent cartridge shells for cartridges when this will happen. I am 3D CAD designer.

Tomek-8 for ATARI 800 homecomputer... based on PIC32
Hires
http://www.youtube.com/watch?v=3Uqtxvnk8f0
Lowres
http://www.youtube.com/watch?v=kfnsgPS6vdg&feature=plcp
Atari cant do lot of sprites at one screen...

BTW Can you add on cartridge soundchip too? Simply extra channels, mp3, MIDI playback. VLSI solution from Finland webpage: vlsi.fi
Produce VS1053 or VS1103, VS1003. And there are more chips from VLSI.FI manufacturer. 64channel MIDI or MP3 or OGG playback for 10USD.
Watch this VS1103: http://www.youtube.com/watch?v=LjpYxFjps84
So we will have superfast graphics plus extra channels ARCADE like AUDIO on one cartridge...

Chilly Willy
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Post by Chilly Willy » Tue Dec 11, 2012 8:11 pm

tinctu wrote:I will produce transparent cartridge shells for cartridges when this will happen. I am 3D CAD designer.

Tomek-8 for ATARI 800 homecomputer... based on PIC32
Hires
http://www.youtube.com/watch?v=3Uqtxvnk8f0
Lowres
http://www.youtube.com/watch?v=kfnsgPS6vdg&feature=plcp
Atari cant do lot of sprites at one screen...
And I want one of those carts! :D

BTW Can you add on cartridge soundchip too? Simply extra channels, mp3, MIDI playback. VLSI solution from Finland webpage: vlsi.fi
Produce VS1053 or VS1103, VS1003. And there are more chips from VLSI.FI manufacturer. 64channel MIDI or MP3 or OGG playback for 10USD.
Watch this VS1103: http://www.youtube.com/watch?v=LjpYxFjps84
So we will have superfast graphics plus extra channels ARCADE like AUDIO on one cartridge...
If a 200+ MHz SH2 or ARM is used, MIDI/MP2/OGG playing would be simple. The question is, what kind of output do you want... 16-bit stereo to the line-in on the cart port (like the 32X uses)? That may require a codec and associated circuits on the exp board. DMA a buffer to the 32X or MD to play? That then limits you to what the base is capable of (9-bit stereo @44kHz/10-bit stereo @22kHz on the 32X, and 8-bit mono @ ~26kHz on the MD).

EDIT: That VS1103b looks pretty cool! If you wanted a codec on the board, that might be a neat one to use given what it can do. :D

EDIT 2: Checking the VSLI web store, the 1103b is the same price as the 1053b, which can decode MP3, OGG, AAC, etc. So iffen you was to use an 1103, might as well use the 1053 instead! :lol:

tinctu
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Post by tinctu » Wed Dec 12, 2012 6:53 am

Yes vlsi vs1053 is for 500+ 3.144eur so not bad price for that chip.
I think it will run itselfs withouth ARM cpu speed... You just send data to vlsi...

Or as you wrote. Can be OGG, MOD, XM 8bit or 16bit pcm or dac playback soundcard... Amiga or PC Covox like soundcard... But that vlsi is in dac price and got really nice sound...

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Post by TmEE co.(TM) » Wed Dec 12, 2012 8:00 am

You need a separate MCU with the chip, it wont work on its own. The MCU needs to be able to supply data as soon as it is needed, over SPI... 68K will not be able to keep up, ever.
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Chilly Willy
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Post by Chilly Willy » Wed Dec 12, 2012 8:01 am

tinctu wrote:Yes vlsi vs1053 is for 500+ 3.144eur so not bad price for that chip.
I think it will run itselfs withouth ARM cpu speed... You just send data to vlsi...

Or as you wrote. Can be OGG, MOD, XM 8bit or 16bit pcm or dac playback soundcard... Amiga or PC Covox like soundcard... But that vlsi is in dac price and got really nice sound...
Yeah, since it's doing the decoding, you don't need a big processor to do it if you used one as the sound codec on the board. The processor could concentrate on the video while the VS1053 played the MIDI (for cart games) or streamed ogg (for CD games).

I noticed that all but two of the VLSI chips are the same price in low quantities, so you might as well use the best of the lot.
TmEE co.(TM) wrote:You need a separate MCU with the chip, it wont work on its own. The MCU needs to be able to supply data as soon as it is needed, over SPI... 68K will not be able to keep up, ever.
The idea is you have an SH2 or ARM CPU as the main coprocessor, and then use the VS1053 as the sound codec. You pretty much NEED some kind of sound codec... maybe built into the SH2 or ARM, but if it was external, then going with the VS1053 makes sense - it's both the codec AND a decoder for compressed audio or MIDI.

RayR
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Post by RayR » Fri Dec 14, 2012 12:28 am

I'm just trying to clear something up. When a DSP cart is created for the Mega Drive we are stuck at 15 FPS NTSC no matter the processing power. Just like the Virtua Racing game. If so, is there any other way around that, maybe a internally wired video board. I know that's way to much work for the average gamer who wants ease of use. A cart would be the way to go for better adoption of an add on.

Here is another DSP cart from the MSX community. Pretty cool.

http://www.msx.org/news/hardware/en/tms ... -available

Come on Sega community lets join the fun!

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