Megadrive was always the answer

Ask anything your want about Megadrive/Genesis programming.

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danibus
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Re: Megadrive was always the answer

Post by danibus » Sat Sep 07, 2019 7:13 am

Main idea is 2 megadrives, as simple as possible, to start programming with actual resources and be able to make new games asap.

This is just a theoretical exercise, I don't have any target price, it's a funny thing design theorical-but-possible new megadrive expansion, just as we did when were children.

But is not really a *new* expasion, this is the point.

I saw FPGAs around 60€, don't know cheaper FPGAs were possible. Sure still some extra stuff to mix video output, connectors, etc.

Cartridge slot will be nice but it's not compulsory, better to avoid and use just a SD slot.
I would avoid sound, as Yamahas are not well supported, also to avoid extra cost and avoid programmers to do extra work.

Not sure if FPGA could work without extra A.C....

djcouchycouch
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Re: Megadrive was always the answer

Post by djcouchycouch » Sat Sep 07, 2019 12:12 pm

I still like the idea that it should be two actual Megadrives. Video is mixed 32x-like. The second Megadrive is a slave and soundless. The game developer works with a second set of VDP ports that feed directly to the second Megadrive. Maybe make the CPU available somehow, but I wouldn't cry too much if it wasn't.

Sure it's ungainly but I think it's kinda neat.

Chilly Willy
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Re: Megadrive was always the answer

Post by Chilly Willy » Sun Sep 08, 2019 12:00 am

Why make the slave soundless? Mix it with the other MD either via the video mixing section, or using the audio in lines on the cart of the master MD. Two YM2612/PSG would be VERY helpful for games.

TmEE co.(TM)
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Re: Megadrive was always the answer

Post by TmEE co.(TM) » Sun Sep 08, 2019 1:23 am

Faster CPUs, more RAM and just enhancing VDP and sound is far more useful and much more doable... getting the two sides share single cart is not going to happen more or less though just adding second VDP (and not doing DMA with it) can work out to some extent. It does take a significant FPGA to fit two MDs into one... lot less effort is needed to just boost capability of the existing design. (how is that enhanced MD project going ?)
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danibus
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Re: Megadrive was always the answer

Post by danibus » Sun Sep 08, 2019 6:07 am

Chilly Willy wrote:
Sun Sep 08, 2019 12:00 am
Why make the slave soundless? Mix it with the other MD either via the video mixing section, or using the audio in lines on the cart of the master MD. Two YM2612/PSG would be VERY helpful for games.
At the moment FPGAs and Yamahas are not friends. If cost are to be keep as low as possible, avoid extra chips will be hepful.
Of course, will be nice to have 2 YM2612/PSG.

KanedaFr
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Re: Megadrive was always the answer

Post by KanedaFr » Sun Sep 08, 2019 8:56 am

I really like the 2 MD idea.

Won't it be possible to use a slave MD like did with the MCD ?
Is it possible to have a "slave cart" on the slave MD with all the logic and send message to the slave ? I don't remember of the MD/MCD sync is done but something similar will be needed ...
Even more, could the slave cart include the video mixer ?
It will then "only" requires 2 MD, a cable between the 2, a slave cart with 2 video input and 1 output....

For my point of view, a FPGA solution won't be a MD extension, but a new system.
My 2 cents to this far-to-be-ended topic ;)

djcouchycouch
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Re: Megadrive was always the answer

Post by djcouchycouch » Sun Sep 08, 2019 11:18 am

Chilly Willy wrote:
Sun Sep 08, 2019 12:00 am
Why make the slave soundless? Mix it with the other MD either via the video mixing section, or using the audio in lines on the cart of the master MD. Two YM2612/PSG would be VERY helpful for games.
No reason other than to simplify things and I'd just be interested in VDPx2. But it's not like I'd have time to make a game for the thing so whatever they like :)

danibus
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Re: Megadrive was always the answer

Post by danibus » Sun Sep 08, 2019 12:13 pm

KanedaFr wrote:
Sun Sep 08, 2019 8:56 am
I really like the 2 MD idea.

Won't it be possible to use a slave MD like did with the MCD ?
Is it possible to have a "slave cart" on the slave MD with all the logic and send message to the slave ? I don't remember of the MD/MCD sync is done but something similar will be needed ...
Even more, could the slave cart include the video mixer ?
It will then "only" requires 2 MD, a cable between the 2, a slave cart with 2 video input and 1 output....

For my point of view, a FPGA solution won't be a MD extension, but a new system.
My 2 cents to this far-to-be-ended topic ;)
Won't it be possible to use a slave MD like did with the MCD ?
If we use MCD way of work, we need to send tiles accross main bus and use MD VDP.
MCD was amazing as we have lot of space for ROM (many sprites and backgrounds, prerendered videos) and also can make some magic with sprites (like rotations)... but then we can't improve image, as we still have 64 colors, 2 HW planes + 1 sprite plane.

Using master/slave aproximation (like SH-2 with 32X) is a mess, better each MD doing their work and just use main bus connection to send minimal data and coordinate game.

It will then "only" requires 2 MD, a cable between the 2, a slave cart with 2 video input and 1 output....
Too much things to be connected, nobody would have this in home, I think.

For my point of view, a FPGA solution won't be a MD extension, but a new system.
Yes, it's new system, almost identical to mother system (except sound and something to connect them) + video mix.

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