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This is done, instead of trying to implement everything to start with, not just because of laziness and lack of time.

Very informative: MESS has the same goal as MAME, which is to emulate as accurately as possible the hardware of a given computer or video game system.

This goal is fundamentally incompatible with the philosophy of emulators such as BasiliskII (and to a slightly lesser extent, vMac) which use hacks to simplify the emulator or increase performance.

Essentially what the MESSMAME people do is reverse engineer the behavior of the integrated circuits which make up computer systems and virtually put them together into complete machines.

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This makes the MESSMAME code base a great resource for authors working on their own emulators, since many of the ICs that exist in MAMEMESS are found in machines from multiple manufacturers and MESSMAMEs code might provide better insight in the working of the chips than even the original data sheets might.

However, unless a given emulator is similarly built to emulate the hardware of a machine rather than the behavior its less easy to import a complete emulator back into MESS.

Essentially vMac emulates a 68k CPU, a hunk of RAM, and just enough hardware stubs to trick the ROM into booting.

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The ROM itself is patched so it no longer attempts to access the hardware disk controller, and instead transacts all disk IO through a driver which links directly to a system able to handle virtual disk images of arbitrary sizes.

By contrast, MESSs mac.c emulator assembles a complete virtual Macintosh from a library of IC definitions, some of which work more completely then others, and then boots a completely unmodified ROM.

Which means that MESS has to emulate the IWM controller well enough to fool the ROM into thinking its getting data from real 400800k disks, it has to emulate enough of the NEC SCSI controller to allow the system to believe it has a real hard drive attached, etc, etc.

Anyway, the end result is that MESS burns a lot more CPU than vMac and is clunkier and far less friendly to use.

However it does emulate a real Macintosh, not simply a Macintosh-like environment which depends on ROM patches.

Of course, last I checked MESS still couldnt boot System 7 because of unresolved issues with various individual components, but.

Theyve pretty much nailed most 8-bit platforms you can think of, but beyond that things tend to be perpetually in progress.

Do you know how the.hd files for MESS should be created Did you manage to run the LC emulation Best wishes.

I believe that is more a reasonable description of how Basilisk II operates.

No other hardware is emulated, and the the ROM is patched so as not to try to use the hardware.

It is true that the floppy disk drive hardware isnt emulated at all, with the ROM patched to replace the driver.

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But other hardware is emulated, as needed for specific Macintosh software to run.

There is fairly detailed emulation of parts of the VIA, and the RTC.

There is very limited emulation of the SCC, just enough to emulate it when nothing is attached to the port.

The same ought to apply to SCSI, but work needs to be done there.

When software tries something that hasnt been emulated yet, an error message is displayed.

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