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    Why is the G4 limited to 2GB Ram? Boot rom? Firmware? Memory Controller? Could that be patched?

    I have a fondness for geographically addressed slots like the Apple II and NuBus, but those systems suffer from fixed-size memory partitions per card. The Apple II's were way too small so that all of the later interesting cards circa 1986 were heavily bankswitched. NuBus's partitions were too...
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    Why is the G4 limited to 2GB Ram? Boot rom? Firmware? Memory Controller? Could that be patched?

    The MacRISC architecture as defined by Gary Davidian pretty much sets the 2GB limit. Initially because NuBus takes almost 2GB of space for a 6-slot machine, and then they just didn't change that when PCI happened.
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    Introducing ZuluSCSI Blaster - now with More Cowbell!

    I've been told the issue was that they couldn't get DMA to play nice with System 7 virtual memory. So if VM was on you'd get random trashing of disks and memory. That isn't *that* hard of a problem, and they obviously did work it out later for the PowerMacs. Incidentally, 04-22-90 is almost a...
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    Introducing ZuluSCSI Blaster - now with More Cowbell!

    The IIfx hardware assumed the DMA mode would be used. Mac OS never did, and the fallback modes are a bit more fiddly than the "classic" equivalents. A NuBus SCSI card that can do DMA would likely greatly outclass the built-in.
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    Problem getting Marathon working on MAME

    Yeah, 0.276 has no Mac related changes. 0.277 will fix the built-in SONIC Ethernet on the Quadras (the chip's manual kind of glides over some details that both Mac OS and the Sony NeWS workstations that run in MAME were having problems with) and there may be some other fixes, we'll see what...
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    Problem getting Marathon working on MAME

    MAME 68040 machines currently all have a "full" '040 because disabling the FPU gives me a sad Mac. I solved that relatively recently for '030 machines (most of those now have a configuration option for FPU or not) but how Apple detects an LC040 vs. a full one has eluded me. If anyone has any...
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    Performa 550 vs Macintosh TV

    Fizzbinn: you are correct. The biggest issue I had getting the Mac TV to boot in MAME initially was when I assumed it was LC III / 5x0 based. It's not. From software it looks almost exactly like an LC II or Color Classic. The memory controller is the only real difference from the V8 so it...
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    How long until we see enhanced mac motherboard recreations?

    The ZuluSCSI/BlueSCSI "toolbox" support in the most recent MAME versions gives pretty simple file sharing. Just run @saybur 's awesome ScuzEMU (https://github.com/saybur/scuzEMU) and you can upload/download files to the machine MAME's running on. It's not quite as seamless as Basilisk but it's...
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    Wombat (650, 800) board overclocking limitations

    That's fantastic! Is the board roughly compatible with stock ATX style mounting screw positions, or how did you pull that off?
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    Can the Macintosh Plus be modified to support 16MB RAM?

    The Portable/PB100 can have 9 MB of actual RAM, the on-board video is in what would be the NuBus slot space.
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    Connecting to Raspbian Window Server with MacX

    Interoperating modern and vintage X clients and servers is very difficult. XRandR allows live video mode switching, which wasn't important in 1987 and was critical in 1997. MAME emulates some 68k-based dedicated X terminals and they work best with a similar-vintage machine (a SPARCStation or...
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    AE Z80 Plus does not working 60k version CP/AM 5.1

    Because of the way those cards work (the AE cards are SoftCard clones) it's unlikely to be the card's fault. Have you tried downloading a fresh copy of the 60 and 63K versions?
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    Mac SE ADB Controller

    I found a race condition in the original Apple code that the PIC was sometimes losing under emulation due to the different timing (time-slicing the emulated CPUs rather than trying to run them actually simultaneously). The upshot is that on the last bit of a byte being sent from the main CPU...
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    Introducing scuzEMU, a SCSI Emulator Utility

    Thanks @saybur ! Its been great for me too, I can download drivers or whatever for things I'm working on and immediately have them in the emulation.
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    An IIsi in my SE/30? It's more likely than you think!

    Yeah, not many ROM dumps exactly match SuperMario, and the closest ones are quite a bit later than the IIsi.
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    An IIsi in my SE/30? It's more likely than you think!

    This is the kind of fun hack I really love. The idea of combining this with a PPC upgrade would be kind of hilarious. You can probably eliminate the ROM patches (which would likely be important for making a PPC card work) by just jumping the ID pins appropriately...
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    Macintosh Personal Color, a Fantasy 1986, 68000 Mac with a 4bpp Color Mode (Emulator)

    Common fan theory, but the IIgs hardware engineers have indicated it's because there were no 65816s that would reliably run above roughly 3.5 MHz. Sanyo and Nintendo had to redesign the chip to run the Super NES reliably at 3.58 MHz (and that also enabled IIgs accelerator cards). John Sculley...
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    Mac IIci MDU / RBV registers

    Ahh, no, don't have anything on that.
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    Mac IIci MDU / RBV registers

    The IIci's GLUE chip? No, I don't.
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    PowerBook Duo battery replacement

    Having a good PRAM battery is important since the PG&E power manager's firmware is kept in the same battery-powered SRAM as the PRAM. When that goes dead the power manager is stuck with a tiny 512 byte bootstrap where all it can do is turn on the main CPU and hope it downloads a complete 32K...
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