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Concept: MacintoshX - Game like its 1991, compute like its 1986!
- Thread starter Nixontheknight
- Start date
An interesting idea. There was mention of sharing the CPU and it sort of implied that the FPGA swaps attention between the Mac and Genesis environments as necessary, so I wonder: how does that work? Does the Mac have its own video output separate from the Genesis, allowing gaming and Mac usage at the same time? Otherwise, what's the point in keeping both environments active and sharing cycles? Does the base Genesis hardware have to manage the audio and video outputs on behalf of the Mac environment? And what sort of controls are we using? Genesis gamepads? Is there a separate keyboard/mouse input on the cartridge?
It is possible to crash many commercial Genesis games, particularly if you modify a controller to allow you to press contradictory directions at the same time (up+down or left+right). A very well-used controller will eventually wear down to where you can do that as well.
The TerraDrive had some sharing between the two sides. It was used by some games. This GitHub is someone's experiments with it: https://github.com/RetroSwimAU/TeradriveCode
On topic, other than sharing the same CPU the two platforms are so different to each other it'd be somewhat pointless.
Your best bet would be to take something like the Minimig which had a real 68K and implemented the Amiga Chipset on an FPGA. No reason you couldn't implement the Mac in an FPGA (BMOW started a project to do just that), and a Megadrive core and switch between them. Reserve some memory to share between them if you like.
Or just get the Mister FPGA and run the port of BMOW Mac cofe and a Megadrive Core. Way more flexible! Or go full inception and run the Mac under an emulator on an Amiga Core on an FPGA...
Your best bet would be to take something like the Minimig which had a real 68K and implemented the Amiga Chipset on an FPGA. No reason you couldn't implement the Mac in an FPGA (BMOW started a project to do just that), and a Megadrive core and switch between them. Reserve some memory to share between them if you like.
Or just get the Mister FPGA and run the port of BMOW Mac cofe and a Megadrive Core. Way more flexible! Or go full inception and run the Mac under an emulator on an Amiga Core on an FPGA...
well, the 68000 and 010 have bus request lines, one where a peripheral can request the bus, and one where the 68000 or 010 responds "sure, I'm not doing anything", the FPGA will assert the bus request line, and wait for the 68010 to grant access, where it swaps the entire bus underneath the 68000 and says "ok you may have it back", which I'm hoping doesn't result in the 68010 being confused if it has anything stored in its internal registers
Completely off-topic, my favorite hybrid machine was the LaserActive... Some day, I will own one.
Well, one way I could make it useful is by using the Macintosh side as a development environment for Genesis games, you write the code on the mac side, and put it on a small SCSI disk that the FPGA makes readable to the genesis side
I'm not sure that's a hybrid machine so much as a LaserDisc player that could run specialized interactive discs. Like saying the Sega Saturn was a hybrid machine because it could play CDs as well as games, or the PS2 because it could play DVDs and CDs as well as games.
I actually bought some LaserActive discs when I found them in junk shops. The only machine I came across for sale was well over $500 and was sold "as-is" so I had to pass on it.
Not like that at all! I was referring to its ability to play Genesis & TurboGrafx-16 games with the add-on modules, not at all a dissimilar concept to what the OP is proposing.
I didn’t even realize it had its own “interactive” discs.
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Or how about you just make Genesis games on your PC
but where's the fun in that?
Where's the fun in creating a SBC that isn't integrated with the Genesis?
rerouting the CPU calls to an external CPU
Incidentally, I said before there was a combo PC/Megadrive where the halves can't interact. It turns out there's also the Sega TeraDrive, which is a 286 PC/AT clone with a Megadrive built-in, and both halves can access each other. The 68000 can talk to the VGA card and SoundBlaster and whatever, while the 286 is able to use the Megadrive graphics and sound. One of the other MAME guys has been working on emulating it for the last week or so.
maybe this project could help pave the way in figuring out how the two halves of the TeraDrive interact?
