![]() ![]() I want the emulator to be as good as I can make it myself. SheepShaver does have Ethernet support and CD-quality sound output. I'm also trying to get page table address translation in soon, but I need to refine my BAT translation methods before I dive deep into that.įinally, as for open sourcing it, I want to make sure this emulator can boot up to the NanoKernel before doing so. SheepShaver is an open-source PowerPC Apple Macintosh emulator originally designed for BeOS. It depends on how the rotate/masking instructions are implemented. If you want to know where my emulator gets to before crapping out, somewhere around 0xFFF03048 or 0xFFF0304C. (below addresses apply to Old World ROMs, noting important code locations within the ROMs)įFF00100 - Reset Area (where the ROM begins executing) So, with Macs, while the hardware configurations will inevitably vary between machines, I did manage to come up with a sort of physical memory map of locations common between all the various PowerPC Macs: 00000000 - 7FFFFFFFĨ1000000 - ATI MACH 64 (For G3 Beige, my target ROM, this will be what I'll try to use)į3013000 - Serial Printer Port (0x20 bytes)į3013020 - Serial Modem Port (0x20 bytes)į3014000 - DAVAudio Sound Bus (0x1000 bytes)į3015000 - SWIM 3 Floppy Disk Drive (0x1000 bytes) But it also means several apps that rely on those instructions crash in Sheepshaver.įor my emulator, I've being using this repository to guide me in how the ROMs work: Īnd huge thanks to the person running it, Elliot Nunn, for not only his work in dissecting the ROMs, but also assisting me in getting the ROM to work. PearPC actually does emulation of many of the components required to emulate a Mac, enough to boot it up.Īlso, Sheepshaver doesn't try emulating the supervisor-level instructions, which is a huge reason the hacks exist in the first place (one of the patches for the ROMs actually replaces an rfi instruction). One reason is that it uses the floppy drive emulation to work with hard disks (at least those Sheepshaver makes), hijacking a floppy disk driver built into the OS to do so. And out of frustration, Motorola, IBM, and Apple combined their efforts into one and primarily focused on one processor.Īs for actual emulation, it should come as no surprise that Sheepshaver is very hacky. ![]() ![]() For Apple, first they tried making their own processor (and failed), tried using a Motorola 88000 series processor (and scrapped it), before going with IBM's Power architecture and modifying it to better suit Apple's needs. Long story short so far: it seems like Motorola, Apple, and IBM were all independently working on their own RISC processors. Hello and welcome to yet another look into Mac emulation and my PowerPC Mac emulator.įirst thing to note is I've been doing a little bit of behind-the-scenes work as to how the PowerPC even came into being. ![]()
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