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Thread: Mac OS on a Sega Genesis? Yes!

  1. #16
    Road Rasher
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    So is he forcing an interlaced mode by splitting the two framebuffers to instead act as 'fieldbuffers.'
    That's the only thing that makes sense, unless the 32X does indeed run an interlaced increased res mode.
    However, the horizontal res isn't visible, so it's 'emulated' if it exists. Perhaps something to make it compatible with the mac vid modes.
    The vertical res might be the same story, as the 32x doesn't run in full color at full res. It's mathematically impossible for the number of colors/pixel to fit in 256k of VRAM.
    that's 640x488x15
    4684800 bits.
    About double the VRAM in the 32X.
    However, it also has the same amount of work ram as VRAM, so it's theoretically possible to get the 'Video RAM' up to that level if you don't use it for anything else.

    Personally, I think it's a bit of a waste to emulate invisible pixels and use 2 SH-2s for nothing more than video ram work.
    That's why I like the idea of using it as a solo computing platform.
    A linux port would make things easier for everyone as opposed to writing a new OS or just using the PS/2 interface and hard-coding each program for the hardware(like the old school TV computers and....consoles).
    I propose 'Slimux.'
    Sega Linux. Slime is in there as an ode to the makers of the first viable emulators: Bloodlust software.
    Slinux is too much like Sinus, and 32Linux is just plain confusion.

    In any case, I still have my doubts, but this is a great basis for a 'new' computing platform.

  2. #17
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    How did you get around Cart Detect? I mean, the 'cloned rom' is needed to run the OS right? In that case you'd be running code from the cart port.
    this disables the cd portion.
    The CD couldn't be run if the cart detect isn't diabled.

    This has at least given some insight into how th 32X works. The cart detect must be soft-switched and the dongle is needed because the 32X assumes the presense of the CD portion so the CD can use it.

  3. #18
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    Write a feature about this! It would be great.

  4. #19
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    The resolution of the images and the settings shown don't quite line up.
    60hz?
    It's going to expect progressive...


    It's not possible to get that high quality from an interlaced analog source. It would be blurrier, first of all.
    Second, that resolution will be EMULATED, because it's higher than the max resolution that 32x can put out at that color depth. The problem there is it's supposed to be running some kind of emulated program, that'll need to run in 256k of main RAM. That leaves two SEPERATE banks of frame buffer at 128k each to then get a 320 244 15bpp image to output SOME of the pixels.
    That'd need to be some fucking compact code.

    How can yu get the 32X to run anything but then let the 68000 have direct access to the cart port?
    That video is running too fast for it to be a Genesis as the main proc. It can't access enough memory at once, regardless. The amount of bank switching needed to even get the Genesis to know to access the 'extra RAM...'


    Guys, I wanted this to be true so bad, but I'm now sure it's a hoax...
    Too many things are impossible.

    But, once again, this should be explored as a basis for a Linux platform.
    Again, the main procs should be the SH-2s.
    Last edited by TheGZeus; 12-03-2006 at 10:26 AM.

  5. #20
    Shining Hero Joe Redifer's Avatar
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    It'll be interesting to read evildragon's responses.

    Anyway, I'm not sure if the Genesis/Sega CD/32X setup will allow the SH2's to be the main CPU(s). I think everything is always controlled by Mr. Genesis, and the other processors in the Sega CD and 32X just worry about the special functions of said hardware. Of course I didn't build the things, so that's only my guess based on the games I've seen.

  6. #21
    Fonz Road Rasher
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    Yeah, i'm sure it is an hoax too... ;P peoples that can program so great 32x and segacd are very few... I think i know one only (steve snake probably).
    But who knows....

  7. #22
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    What processors do what work is determined by the programmer mainly.
    Doom, for example has a goofy intro screen with a bug-prone Genesis, but the rest of the game runs fine.

    Mainly, I think the 32X needs the genesis for sound processing and some other small things, and if the programmer wants hardware sprites.
    Otherwise everything is done is software and the programmer has to do more work(not that I know how much work).
    It'd be interesting for someone to play a few 32X games with the video output from the Genesis 'Y'ed off before it gets to the 32X.
    Actually, it would be intersting to see if the the 32x needs the AV in, and what signal it needs.
    This guy saying the 32x needed a 'sync' from the AV was a red flag for me, too.
    It's already syncing to the clock of the Genesis.

  8. #23
    Shining Hero Joe Redifer's Avatar
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    The 32X needs an analog video input from the Genesis to sync. Even on games like Space Harrier and After Burner where the Genesis does next to no video of its own, if you unplug the Genesis A/V input into the 32X, the 32X video loses its genlock and pretty much goes away. You might see some wavy bands of color here and there, but they won't be still. You can plug the Genesis video into a TV bypassing the 32X just to see what the Genesis does. I've tried this at least once on all of my 32X games. For example, on Space Harrier the Genesis does the multi-layered backgrounds (but not the sky) and the text. On Virtua Racing, it does the entire background. On Knuckles' Chaotix, the Genesis does everything except the sprites and some of the text as indicated previously.

  9. #24
    Loves Lori Bazzil! Raging in the Streets 108 Stars's Avatar
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    What would running Mac OS on a Gensis be good for anyway?

  10. #25
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    So one could just take the sync from the Genesis video out and run that into the 32X to see exactly what it's doing.

    In any case, that basically proves that the Genesis isn't the main thing even most of the time.
    The things it DOES do are things that are harder to program all in software.

  11. #26
    Wildside Expert highlandcattle's Avatar
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    I'm not buying this either the images shown are way to sharp to be real.
    So he just simply developped graphics drivers to run macos7 on the genny?

    Get real this as fake as they get.

  12. #27
    YM3438 Master! ESWAT Veteran evildragon's Avatar
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    the Mac OS screenshots are by doing what you do on a real Mac.. you do Apple+Shift+3.. It makes a PICT file on the desktop.. that's a framebuffer grab.. so, duh, it WILL be sharp..

    my LCD does infact have a 15KHz sync rate, and I used the sync splitter circuit to make it work..

    I will try to make an animated GIF or a video file describing how it's working.. yes, the 32X doesn't support interlaced modes, but since the Genesis is driving the sync, and the 32X simply will flash between the even and odd scan lines.. it's VERY hard for me to describe in text...

    remember, the cartridge has extra memory, 32MB of DRAM.. it's been a while since I coded the 32X in action, so I may have allocated some DRAM for it's video.. i do notice my protoboard has a mapper on it, so I might have done just that... (this project is VERY old now, do a Google on it, this didn't come out of nowhere).

    I wouldn't joke about something, cause I get upset when people talk out of their ass

    While on vacation, I tried to write for the Sega CDs PCM, but I really can't find much documentation on the Sega CD...

    I bypassed the Genesis BIOS (license screen), by reverse engineering other Sega Games, and copying the code (Sonic 2 BETA I believe is what I used, since that has been disassembled)

    The 32X SH2 processors are emulating the job of graphics chips.. Mac OS 7, the extensions are allowed low-level things to happen, and with that, it CAN work.. though, during boot, it's only Genesis video, via an emulation layer.. (you can see it starting up in 320x224, and when it loads the extension, the Genesis VDP blanks, interlaces, then the 32X kicks in..

    my 32X interlacing trick is very sloppy.. sometimes the even lines end up on the odds, and sometimes the odd end up on the even lines.. mainly, this happens if the 32X skips a frame (why it's never done)...

    There is NO way, that the 32X's SH2 can run Mac OS.. Mac OS 7 was PPC, and M68k only.. (and there's more PPC code, so half the things don't even run)..

    I am almost done making a printed PCB layout, so I'll soon be able to fit it in a EA-Games cartridge, minus the IDE ribbon coming out, and a piece of the circuit with a RJ-45 connector for the NIC.. (the NIC portion drops a lot of packets.. i need to check that too)..

    Oh, and as far as Mac OS is concerned, it's running on a Mac with only ONE channel SCSI bus (without even the "SCSI adapter"---as it's not there).. if this was Windows, it would NOT work.. pre-OS X Mac OS's, didn't check the system out.. OS X (PPC only), would not allow this either.. not to mention, OpenFirmware would be missing (something Macs also need---PPC Era)..

    I'll try and answer more questions soon.. hopefully this cleared some things up... oh, and the reason i took TV shots of it in the early times, was to try and dis-prove a hoax.. guess that wasn't good enough.. (because you can clearly see the Genesis-composite artifacts)

  13. #28
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    Yeah.
    You didn't address a single thing that was asked of you. Like the fact that it's mathemetically impossible for any of this to be possible period.
    Not enough RAM in the 32X.
    The 68K cannot get direct access to the 'extra RAM.'
    The cart detect has virtually nothing to do with the bios. No one asked about the Genesis bios. The cart detect disables the entire expansion port. Thus. Cart=no Sega CD.
    The videos you are trying to give as proof are proving your claim impossible(the resolution is too high). Why did you bother to claim this high of a resolution? You might have gotten away with 320x240.

    Fake.
    Troll.
    Ban.

  14. #29
    YM3438 Master! ESWAT Veteran evildragon's Avatar
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    the resolution isn't too high, it CAN be done.. look, why would I bother to make a joke? if it wasn't even MY idea to post this? really, please, just dont start anything, it WASNT what I wanted...

    I got confused about Cart detect.. there can be a cartridge inserted and the expansion port be still accessible.. perhaps you forgot of a certain cartridge cartridge called "Flux", which used the Sega CD, but used a cartridge to load the program.. yea, your the one calling me a troll, and requesting a ban, which might I add, wasn't it YOU that verbally attacked Joe?

    the Genesis CAN access the RAM.. how do you think game saves work?

    the 32X can use the extra RAM in the cartridge..

    look, I wasn't the only one who designed this cartridge, I had help from a friend, who knows SH2 assembly (because I couldn't do the 32X portion myself)

    oh, and you can't ban me for saying something I did, just because you don't believe it.. because it's a baseless accusation.. ESPECIALLY because I didn't want to even start this thread in the first place..

  15. #30
    Prince of Shatt Master of Shinobi CMA Death Adder's Avatar
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    It's a shame that these sorts of time-wasting issues are finding their way into the Genesis - Megadrive community. First the bogus Doom port, now this... what's the reasoning, exactly? Why isn't this time spent wisely, developing actual code for the Genesis, rather than using it in an attempt to bolster faux enthusiasm, building people up just so you can then send them crashing down? Is your life really so devoid of purpose?
    - Brandon Cobb
    President, Super Fighter Team

    · Check out Beggar Prince, the new RPG for Sega Genesis / Mega Drive!
    · Nightmare Busters is pretty cool, too. It's for the Super Nintendo.

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